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M-125-3   Fialka
Advanced Fialka cipher machine

The M-125-3, codename FIALKA (Russian: ФИАЛКА), was a Russian electromechanical wheel-based cipher machine, developed during the Cold War by the USSR in the mid-1960s as the successor to the M-125. It features 10 coding wheels, with 30 contacts at either side, that move in alternate directions. The M-125-3 contains a number of improvements over the M-125.

The machine has a card-reader at the left that acts as an extra (static) wheel. It consists of a 30 x 30 contact matrix and allows its permutations to be altered as part of the daily key. The card reader is comparable to (but cryptographically stronger than) the plugboard of the Enigma.

Like the Enigma, the electric current enters the wheels from the right via a static disc (the entry) wheel. The current path is returned through the wheels by means of a reflector at the left. Unlike Enigma however, on which a letter can never be encoded into itself, Fialka features a clever 'magic circuit' (German: Dreipunktschaltung) that does allow a letter to be encoded into itself.

Nation-specific variants were made for the various countries of the Warsaw Pact. These had keyboards and print heads that were adapted for the local language. Furthermore, the cipher wheels had a country-specific wiring, so that during piecetime the various countries could not communicate with each other using Fialka.
  
Fialka M-125-3 with open lid

Like its predecessor, the M-125, the M-125-3 contains a paper tape puncher, a printer and a paper tape reader. Furthermore it has a digital 5-bit data output at the right rear, that can be used to drive a telegraphy system or a transmitter directly. It can also be used for adding extra security to the system, by connecting it to the advanced TEMPEST Power Supply Unit (PSU). Two different power supply units are known to have been issued with Fialka machines.

The M-125-3 has a number of improvements over the earlier M-125. If offers better support for the various local languages by adding a Mixed Mode (i.e. letters and number) using a letter-shift and number-shift, plus a Numerical Mode (numbers-only). It also had adjustable cipher wheels. When unused, the machine can be protected by a metal dust cover that also contains the paper feeder, a paper chad box, a crank, a test reflector, spare print heads and a spare set of wheels.

The Fialka with the dust cover on Fialka M-125-3MR2 Fialka M-125-3 with open lid Frontal view of the machine Left side of the machine The right side of the M-125-3 Test connector visible through a hole in the left side of the cover Power switch and TEXT MODE selector
The print head, the printer lift and the capstan, visible through a hole in the top lid. MODE selector and Print/Punch control lever The dust cover removed from the machine Accessories stored inside the dust cover Message form placed in the copy holder Czech version of the Russian M-125-3 cipher machine
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The Fialka with the dust cover on
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Fialka M-125-3MR2
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Fialka M-125-3 with open lid
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Frontal view of the machine
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Left side of the machine
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The right side of the M-125-3
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Test connector visible through a hole in the left side of the cover
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Power switch and TEXT MODE selector
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The print head, the printer lift and the capstan, visible through a hole in the top lid.
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MODE selector and Print/Punch control lever
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The dust cover removed from the machine
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Accessories stored inside the dust cover
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Message form placed in the copy holder
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Czech version of the Russian M-125-3 cipher machine

M-125-3 versus M-125
Compared to the earlier M-125, the M-125-3 has the following extra's:

Country-specific variants
The base of the machine (and the internal wiring) was the same for all countries of the Warsaw Pact, but for each country a customised version of the Fialka was issued, identified by a suffix to the model number (e.g. M-125-3MN for Czechoslovakia). This involved the layout of the characters on the keyboard, an extra print head and the country-specific wiring of the cipher wheels. So far, the following country-specific variants have been identified:

Controls
The M-125-3 Fialka was a very complex, jet easily controlled, electromechanical cipher machine. It had only two electrical connections, one at the left and one at the right, and all controls were conveniently spread over the body of the machine. After connecting the machine to the Power Supply Unit (PSU), it was switched ON by placing the ON/OFF switch in the БКЛ.-position.

M-125-3 Fialka seen from the front right

The 30-character keyboard is located at the front of the machine, with a black spacebar in front of it. When typing a message, a copy holder can conveniently be raised to hold the message form. A ruler holds the form in place and can be used as a pointer by moving it up and down. At the front right is a paper tape reader that is mechanically coupled to the keyboard. It is used to play back previously recorded messages. To the right of the copy holder is the MODE selector.

M-125-3 Fialka seen from the front left

The image above shows the machine as seen from the front left with the copy holder lowered. At the left of the machine is a drawer that can be opened. It holds a punched paper card that is part of the daily key settings. A resettable counter at the front left is used to count the number of characters that are entered. At the right rear is a combined printer/puncher.

Mode of operation
A three-position lever in the large red circular 'blob' to the right of the drum, is used to select the required mode of operation. It is called the MODE selector and is used to select between Coding, Decoding and Plain Text. Furthermore, a vertical lever at the rear right (just behind the printer) is used to select the desired TEXT MODE. It has three possible settings and allows selection between Letter Mode, Number Mode and Mixed Mode. The settings are explained in the following table:

Label Russian Phonetic English
О Открытый Текст Otkrytyj Tekst Plain text
З ЗашифроватЬ Zashifrovat Cipher
Р РасшифровыватЬ Rasshifrovyvat' Decipher
Б Буквы Bukvy Letters
С Смшанные Smjeshannyje Mixed
Ц Цифры Cifry Numbers
ПФ Перфорация Perforacija Punch 1
ПЧ Печатание Pechatanije Print

The lower two entries in the above table are the settings of the Print/Punch control lever, that is located to the right of the MODE selector and is part of the same red 'blob'.

  1. Please note that the ПФ position of the Print/Punch selector, is affected by a 2-position rotary switch (marked ПЧ) at the bottom of the machine. When set to ВКЛ (ON) the printer is activated. In this mode, the paper tape contains punched data as well as text. When set to ОТКЛ (OFF) the printer is disabled. If your machine behaves differently, it is likely that it hasn't been assembled correctly after a repair.

Multiple character sets
The basic Fialka machine supports 30 different characters and was designed for the Russian language and the Cyrillic character set. As Cyrillic has more characters than Latin, the usual 26 characters were not sufficient. In order to avoid mechanical complexity of the electric wheels, the 30 most frequently used Cyrillic characters are used. These are the following characters:

А Б В Г Д Е Ж З И К Л М Н О П Р С Т У Ф Х Ц Ч Ш Щ Ы Ь Ю Я Й

On each Fialka machine, regardless the country in which is was used, these 30 characters are always at the same position on the keyboard and on the print head. As the same characters are used to identify the position of a cipher wheel, we will use these Cyrillic letters as the reference.

Evolution from Russian keyboard, via Russian/Latin into Mixed-mode keyboard.

On the earlier M-125, it was possible to switch between Russian and Latin. For this, two letters were printed on each key top: a Cyrillic one in green (left) and a Latin one in red (right). The position of the Latin characters varies per country. Numbers were not present on the keyboard and had to be typed in full (e.g. in German: 'dreisieben' instead of '37').

On the M-125-3 support was added for additional characters and punctuation marks, by adding a Letter-Shift and Number-Shift, just like on a teleprinter (Telex). This was implemented by giving up two of the existing keys: The leftmost key (ФA) and the rightmost key (Ж5) of the middle row. The (ФA)-key was used to switch to Numbers and was marked as (1...), whilst the (Ж5)-key, now marked with (A...) was used to return to Letters. In order to maintain compatibility with users of the old M-125, it was possible to switch between old and new modes.

Layout of the Polish variant of the M-125-3 (Fialka) machine

The image above shows the layout of the Polish keyboard. Depending on the mode in which the machine is used, each key can have four different functions. Switching between the different modes is done with a metal lever at the back of the machine, just behind the printer mechanism.

Example of a key-top with four characters of the Czech keyboard

The key-top can be divided in two halves: the left half (printed in green) is used when the Cyrillic print head is placed in the machine, whilst the right half (printed in red) is for used with the country-specific Latin print head. The lower half of the key-top is used when the machine is used in Letters-only mode (i.e. the mode that is compatible with the old M-125).

When used in Mixed-mode (letters and numbers) both the upper half and the lower half are used, depending on which of the (1...) and (A...) keys was pressed first. To make matters even more complex, the machine also has a NumLock mode (i.e. numbers-only), in which case the character in the upper left corner of the darker keys are used. The diagram below should clarify this:

The function of the 4 characters of each key, in different modes

Numbers-only mode   NumLock
Another improvement of the M-125-3 over the M-125, was the addition of the 30 ↔ 10 switch at the left side of the machine. It reduced the number of keys on the keyboard from 30 to just 10, allowing the machine to be used for numbers-only telegrams (e.g. weather reports).

The darker keys that are used in NumLock 10 mode

When set to '10', only 10 of the 30 keys can be operated; the rest is blocked. As the keys that are used in this mode are scattered all over the keyboard, these keys are somewhat darker than the others. Please note that the NumLock 10 mode can only be used with the Cyrillic print head. Furthermore, it requires the TEXT MODE lever (at the rear right) to be set to the Ц-position.

MODE selector and Print/Punch control lever Power switch and TEXT MODE selector TEXT MODE selector TEXT MODE selector seen from the rear The NumLock selector (10-30) Setting the NumLock selector to '30' (letters) Top view of the keyboard after the cover has been taken off Close-up of the keyboard
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MODE selector and Print/Punch control lever
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Power switch and TEXT MODE selector
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TEXT MODE selector
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TEXT MODE selector seen from the rear
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The NumLock selector (10-30)
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Setting the NumLock selector to '30' (letters)
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Top view of the keyboard after the cover has been taken off
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Close-up of the keyboard

Cipher wheels
The M-125-3 uses 10 cipher wheels, each of which has 30 flat-faced electrical contacts at one side and 30 spring-loaded contacts at the other side. The 30 positions of each wheel are marked with the 30 letters of the Cyrillic (Russian) alphabet, in this order:

А Б В Г Д Е Ж З И К Л М Н О П Р С Т У Ф Х Ц Ч Ш Щ Ы Ь Ю Я Й

Each of the 10 cipher wheels is wired differently and has a number of pins at the outer rim that are used to control the stepping of the wheel next to its neightbour. The number of pins and their position are different for each wheel and for each country. The 10 wheels and their wiring cores are marked with the following 10 letters of the Cyrillic alphabet:

А Б В Г Д Е Ж З И К

Initially, the M-125-3 was issued with non-adustable wheels, just like the earlier M-125. This means that the internal wiring was fixed and could not be removed or altered. This changed when in 1978, new adjustable wheels were released as part of the PROTON-2 directive. Under this directive, a new operating procedure was initiated, together with new wheels of which the wiring core could be removed. The PROTON-2 wheels were backwards compatible with the older wheels.

The removable core of the PROTON-2 cipher wheels

Each side of a wiring core is numbered (1 and 2) allowing them to be reversed. The wheel core can be inserted into a wheel in 30 different positions and another 30 positions when reversed. Furthermore, the core of one wheel can be inserted into another wheel (with different notches).

When the wiring core is placed with side '1' up and the white mark lining up with the letter 'A', the wheel is backwards compatible with a non-adjustable wheel with the same identification letter. This is called the 'basic position'.

Another improvement of the PROTON-2 wheels over the old non-adjustable fixed wheels was the addition of the Ring Setting, which is comparable to the ring setting of the Enigma. It changes the offset between the position of the advance blocking pins and the wiring core. In the basic setting, the ring should be set to 'A'.
  
The wiring core removed from the wheel

Two full sets of wheels were issued with each Fialka: an operational one that was placed inside the machine, and a spare one in an aluminium container that was stored inside the dust cover. The wheels of the operational set had black lettering, whilst the letters on the spare set were red. Each wheel had a single letter in the alternative colour, so that it could easily be identified. Please note that the wheel wiring and the position of the pins was different for each country.

 The cipher wheels in more detail
 Wheel wiring in more detail

The cipher wheels inside the machine, with the ruler in the normal position. Raising the ruler Releasing the entry wheel Taking the drum (i.e. the spindle with the 10 cipher wheels) out of the machine Placing the drum Close-up of the cipher wheels Fialka cipher wheel with special opener Opening a wheel with a special tool
Bottom side of a wheel with the spring-loaded contacts Close-up of the bottom side of a wheel Close-up of the top side of a wheel, with the flat-faced contacts. Close-up of the pins that control wheel stepping The wiring core removed from the wheel Wiring core removed from the wheel The retaining clip removed from the wheel Fialka wheel opener
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The cipher wheels inside the machine, with the ruler in the normal position.
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Raising the ruler
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Releasing the entry wheel
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Taking the drum (i.e. the spindle with the 10 cipher wheels) out of the machine
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Placing the drum
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Close-up of the cipher wheels
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Fialka cipher wheel with special opener
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Opening a wheel with a special tool
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Bottom side of a wheel with the spring-loaded contacts
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Close-up of the bottom side of a wheel
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Close-up of the top side of a wheel, with the flat-faced contacts.
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Close-up of the pins that control wheel stepping
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The wiring core removed from the wheel
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Wiring core removed from the wheel
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The retaining clip removed from the wheel
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Fialka wheel opener

Wheel stepping
When looking at the wheels from the top of the machine, the odd wheels move towards the front of the machine, whilst the even wheels move towards the rear. Wheels 2 and 9 are always advanced when a key is pressed. Stepping of the other wheels is controlled by the position of the notches or pins at the rim of another wheel. This is illustrated in the drawing below:


In principle, all wheels can make a single step in each key-press, but its stepping can be inhibited by its controlling wheel. Wheel 2 controls the stepping of wheel 4. If a pin is present at a certain position, it inhibits the stepping of wheel 4. For this reason the pins are also known as 'advance blocking pins'. In the same way, wheel 4 controls the stepping of wheel 6, and so on. For the odd wheels, wheel 9 is the driving one. It controls wheel 7 that in turn controls wheel 5, etc.

 Wheel stepping in more detail

The cipher wheels inside the machine, with the ruler in the normal position.
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The cipher wheels inside the machine, with the ruler in the normal position.

Card reader
The M-125-3 has a card reader that adds an extra layer of permutations to the machine. The card reader is located at the left side of the machine and consists of a drawer that gives access to a 30 x 30 contact matrix. In many respects it can be seen as a non-moving programmable wheel.

The permutation matrix is 'programmed' by means of a punched paper card with 30 holes: one for each row/column combination. The card is placed inside the drawer, using two alignment pins to ensure its position. Once the key card is in place, the drawer can be closed again.

Compared to the German Enigma machine, the card reader takes the place of the Enigma's Steckerbrett (plug board), but offers a stronger permutation as it is not self-reciproke. The latter is considered a cryptographic weakness of the Enigma that helped codebreakers during WWII.
  
Key card placed in the drawer of the card reader

As the Fialka uses a reflector, just like Enigma's Umkehrwalze, the current passes the card reader twice. In practice the punched card was part of the daily key and was changed every 24 hours. It was made of paper that was so thin that it easily got ripped, so that it could not be used twice.

 The key cards in more detail
 The card reader in more detail

Close-up of the card reader seen from the left side The card reader at the left side of the machine Pulling out the drawer of the card reader The empty card reader Placing a key card Key card placed in the drawer of the card reader Closing the drawer Test-triangle in the drawer of the card reader, creating the 'unity matrix'
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Close-up of the card reader seen from the left side
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The card reader at the left side of the machine
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Pulling out the drawer of the card reader
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The empty card reader
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Placing a key card
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Key card placed in the drawer of the card reader
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Closing the drawer
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Test-triangle in the drawer of the card reader, creating the 'unity matrix'

Printer
Unlike the WWII German Enigma machine, that presented its output on a panel with 26 lamps, the Fialka can print its output directly on a paper strip that could be used directly in a telegram. In addition, the machine could also punch the message into a standard 5-level teleprinter tape.

The combined printer/puncher is located at the right rear and is visible through a hole in the top lid of the machine, just behind the copy holder. The printer consists of a rotating print head with one or two rows of characters. A lift mechanism determines which of the two rows is used. The paper strip moves behind the print head from right to left and leaves the machine at the left.

In between the print head and the paper strip is a standard typewriter-style ink ribbon. When the required character is facing the paper strip, a hammer is released from the rear of the paper.
  
The print head, the printer lift and the capstan, visible through a hole in the top lid.

The hammer momentarily pushes the paper strip (and the ink ribbon) against the print head, causing the character to be printed. When using standard 5-level paper tape, the integrated puncher stores the message on the paper strip by punching out the required holes, whilst the same message is printed as text at the position of the sprocket holes (albeit at an offset).

The Fialka accepts two paper sizes. In addition to the standard 5-level teleprinter tape, it is also possible to print the text on a narrow 10 mm paper tape. This tape is entered from the rear of the machine and uses a different path to the printer, bypassing the puncher. When this type of paper is used, the tape guide (behind the ink ribbon) has to be adjusted accordingly. When pre-gummed tape was used, it could directly be glued onto a telegram sheet or message form.

 The printer in more detail

The print head, the printer lift and the capstan, visible through a hole in the top lid. The cipher wheels inside the machine, with the ruler in the normal position. Close-up of the print head lift 5-letter groups enable/disable switch The power section and the ink ribbon. At the right is the printer head. Close-up of the printer Pulling the paper through the hole at the right The paper tape leaving the machine at the left
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The print head, the printer lift and the capstan, visible through a hole in the top lid.
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The cipher wheels inside the machine, with the ruler in the normal position.
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Close-up of the print head lift
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5-letter groups enable/disable switch
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The power section and the ink ribbon. At the right is the printer head.
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Close-up of the printer
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Pulling the paper through the hole at the right
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The paper tape leaving the machine at the left

Tape Reader
The M-125-3 has a fully integrated paper-tape reader that accepts standard 5-level teleprinter tape in the specific Fialka encoding standard. It is located at the front right of the machine and is mechanically coupled to the keyboard. It can be used to play back previously created messages.

The image on the right shows the tape reader. A small lever, just below the red button, allows the reader to be opened after which a tape can be inserted. After closing the reader, the message is played back by pressing the ПУСК button (start).

When running, the tape reader directly actuates the five coding rods underneath the keyboard, as if the keys were actually pressed. After the green ПУСК button is pressed, the tape runs until the red СТОП button (stop) is pressed or a NULL character (00000) is encoutered on the tape. The keyboard is then decoupled again.
  
Paper tape reader at the front right

Although it was technically possible to connect the Fialka directly to a transmitter using the DATA output socket, this was not recommended. If the machine was accidently left in the О-position (plain text) instead of the З-position (coding), the original message would be sent in clear.

In order to avoid this risk, it was recommended that a message was first encrypted on a punched paper tape, using the built-in puncher, and then tested by reading it back through the reader using З-mode (decipher). If this did not result in garbage, the tape would be send in clear. The advantage of this method was that the encrypted tape could also be sent by separate tape transmitter that did not necessarily have to support the same 5-level encoding scheme.

 The tape reader in more detail

The front of the M-125-3 with the tape reader at the right Paper tape reader at the front right Opening the paper tape reader START and STOP buttons 5-level punched paper tape Placing a paper tape in the tape reader Closing the paper tape reader Tape transmitter lever
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The front of the M-125-3 with the tape reader at the right
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Paper tape reader at the front right
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Opening the paper tape reader
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START and STOP buttons
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5-level punched paper tape
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Placing a paper tape in the tape reader
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Closing the paper tape reader
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Tape transmitter lever

Counters
The M-125-3 has a character counter at the front left that is used to count 5-letter groups. The counter is reset by pressing the large push-button at the front of the machine's base. The rightmost digit (marked with a red border) is used counts the characters and wraps around at five (1-5) whilst the remaining 3 digits are used to count the number of 5-letter groups.

Counting the number of 5-letter groups was an important part of the procedure as cipher text telegrams were generally sent this way. When placing the dust cover over the machine and locking it up, a bracket mounted to the front of the dust cover ensures that the large reset button is pressed before the case is closed.

This is done to ensure that the counter is always set to zero when the machine is unused. This way the counter reveals no information about the latest message that was (de)coded. This counter is also present on the earlier M-125.
  
Character counter at the front left. At the bottom the counter reset button.

Counters of this type were commonly used on other Russian cipher machines of the 1960s, 70s and 80s as well, and were probably made by the same manufacturer. As an example: the cipher unit of the M-130 (Koralle) has a nearly identical (black) counter mounted at the top right.

Unlike the earlier M-125 however, the M-125-3 has another counter that is hidden under the keyboard. It can not be reset and was used to get an indication of the machine's usage when it was handed in for service. This extra counter can only be seen when the top cover is removed from the machine. It is protected by means of a lead seal, to prevent tampering with its position.

The image on the right shows the counter, which is barely visible under the keyboard's spacebar. It is mounted vertically to the bottom of the machine and shows a reading of 00111 here.
  
Extra counter hidden under the keyboard

The extra counter is directly coupled to the main driving gear underneath the keyboard and can potentially cause problems. If the counter gets blocked for some reason, it prevents the driving gear from running and can easily block or even damage an otherwise good machine. Remove or replace this counter when it blocks the machine. To the left of the counter is a solenoid that is used for the machine's auto-repeat function. This solenoid is not present on the older M-125.

Character counter at the front left. At the bottom the counter reset button. Character counter and pulse mechanism Extra counter hidden under the keyboard Resetting the main counter when placing the dust cover.
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Character counter at the front left. At the bottom the counter reset button.
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Character counter and pulse mechanism
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Extra counter hidden under the keyboard
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Resetting the main counter when placing the dust cover.

Accessories
The M-125-3 was originally supplied with a number of accessories, tools and spare parts, some of which were stored inside the dust cover. Below an overview of the various accessories that were available. Click any of the thumbnails below to find additional information about the item.

Original check list Metal dust cover that protects the machine and is used to store some accessories Metal box for collecting paper chad from the punched paper tape Paper feeder that holds a fresh paper tape reel Small hand crank for making corrections and for releasing a blocked mechanism Spare print heads Test reflector Spare set of wheels in aluminium can
Canvas wallet with various tools Spare parts and accessories
ZIP
Oil can used for maintenance User manual Standard Power Supply Unit (PSU) Tempest complient Power Supply Unit (PSU) 24V service lamp used for seting up and maintenance Metal test triangle for the card reader
Wheel opening tool Moisturizer for glueing pre-gummed paper strips onto a message form Mechanical and electronic spare parts
Check list
When they were released by the factory, each Fialka machine came with its own hand-written checklist. It shows which items were originally supplied with the machine when it was issued to the users in the field.

Some of the items have been found by collectors over the years, but a few of them remain a mystery to this day...

 More information
  

Dust cover
The Fialka is an extremely compact machine, with many features efficiently cramped into a small space, and the same can be said of the dust cover that slides over the machine from the top and is retained by two locks at the front and two at the rear. It can be carried with a grip at the front.

The rectangular dust cover protects the machine agains dust, water and other hazards, so that it doesn't get damaged during transport.

It is also used to store some of the frequently used accessories. With a clever use of the limited available space, the designers have succeeded in storing the paper reel holder, the paper chad box, the test reflector, two spare print heads, the crank and an aluminium can with a spare set of cipher wheels. The image on the right shows how these are stored. The crank is not visible in this image; it is stored at the bottom right.
  
From left to right: the test reflector, spare print heads, the paper chad box and spare rotors. Paper tape holder at the front.

The dust cover is nearly identical to that of the earlier M-125. The dimensions are the same and most accessories are stored in the same place, with the exception of the paper chad box that is now in between the test reflector and the spare wheel set. The simpler paper chad box of the M-125 used to be stored over the aluminium can of the spare wheel set. The retaining clip, that was used to hold it in place, is still present but is not used here. More about each accessory below.

The dust cover also serves as a safety measure to avoid giving away strategic information. At the front of the cover is a small metal bracket that mates with the counter reset button in the bottom of the case. When re-fitting the dust cover, the counter reset button has to be pressed, before the cover can be closed. This ensures that the counter is always reset when the machine is stored, so that it no longer reveals information about the length of the latest message that was created.

The Fialka with the dust cover on The dust cover removed from the machine Accessories stored inside the dust cover From left to right: the test reflector, spare print heads, the paper chad box and spare rotors. Paper tape holder at the front. Close up of the test reflector and the two spare print heads The paper tape holder, or paper tape supply reel. The crank, stored inside the dust cover Resetting the main counter when placing the dust cover.
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The Fialka with the dust cover on
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The dust cover removed from the machine
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Accessories stored inside the dust cover
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From left to right: the test reflector, spare print heads, the paper chad box and spare rotors. Paper tape holder at the front.
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Close up of the test reflector and the two spare print heads
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The paper tape holder, or paper tape supply reel.
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The crank, stored inside the dust cover
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Resetting the main counter when placing the dust cover.

Paper chad box
When using the machine to store messages on a 5-level punched paper tape, the small circular punched-out pieces of paper leave the machine through a small channel at the right rear, just in front of the Data socket. The chad is collected in the paper chad box that is attached at the right.

The paper chad box is normally stored inside the dust cover, between the test reflector and the spare wheels. Push it down somewhat to release it from the socket and mount it in the two fittings at the right bottom of the Fialka. Slide the box in place by pushing it towards the rear.

Once the box is in place, the paper chad outlet channel should be extended to avoid spilling the chad aside the box. The chad box has a hinged top lid with a small window in it. This lid can be opened when the box is emptied. Further details can be found in the images below.
  
The paper chad box properly installed

From left to right: the test reflector, spare print heads, the paper chad box and spare rotors. Paper tape holder at the front. The paper chad box, stored in between the spare print heads and the spare wheel set. Paper chad box aside an M-125-3 Attaching the paper chad box The chad box attached to the side of the machine Extending the chad outlet channel The fully extended paper chad outlet The paper chad box properly installed
M-125-3 paper chad box M-125-3 paper chad box M-125-3 paper chad box Top view Opening the paper chad box Fialka paper chad box with open hinged top lid Close-up of one of the two fittings Paper inlet
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From left to right: the test reflector, spare print heads, the paper chad box and spare rotors. Paper tape holder at the front.
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The paper chad box, stored in between the spare print heads and the spare wheel set.
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Paper chad box aside an M-125-3
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Attaching the paper chad box
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The chad box attached to the side of the machine
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Extending the chad outlet channel
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The fully extended paper chad outlet
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The paper chad box properly installed
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M-125-3 paper chad box
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M-125-3 paper chad box
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M-125-3 paper chad box
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Top view
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Opening the paper chad box
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Fialka paper chad box with open hinged top lid
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Close-up of one of the two fittings
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Paper inlet

Paper feeder
When using the printer and or the tape puncher, the paper tape has to be fed in from the right of the machine. A suitable tape feeder is stored inside the dust cover. It consists of a square matal plate with several guides and a spool at the center. The spool accepts a fresh reel of paper tape.

At the rear of the machine, a short vertical metal stub is present that allows the metal tape holder to be mounted to the body of the machine. It slides over the metal stub and is retained by two metal clips at the bottom of the machine.

The paper is fed via the paper guides into a large hole in the rear right of the case in such a way that it comes out through the oval hole in the right side of the case. The paper is then fed back into this hole and inserted into the tape puncher. After feeding it in as far as possible, the capstan should be rotated to pull the tape through.
  
Paper tape feeder mounted at the back of the Fialka

Keep turning the capstan, until the paper tape becomes visible at the tape outlet at the left side of the machine. Fialka accepts two different paper sizes: wide and narrow. The most commonly used paper tape is the wide variant that is used for creating 5-level punched paper tape. This is the same paper that is used in Europe and in the US for storing teleprinter messages (Telex).

With Fialka, this paper can be used to punch 5-level data, print text or both. Alternatively, it is also possible to use narrow 10 mm paper tape for text only. When this tape is used, the puncher has to be swiched off by setting the print/punch selector set to ПЧ. Furthermore, the paper guide behind the ink ribbon has to be adjust for the narrow tape.

Reverse side of the paper feeder (i.e. the side that faces the rear of the Fialka) Paper tape feeder with a partly used paper reel installed Accessories stored inside the dust cover The paper tape holder, or paper tape supply reel. Installing the paper feeder Fitting that mates with the metal stub at the rear of Fialka Metal stub for holding paper feeder at the rear of the Fialka Paper tape feeder mounted at the back of the Fialka
The paper feeder mounted at the rear of the machine Preparing the paper tape Inserting the tape from the rear, so that it exits at the right Pulling the paper through the hole at the right Re-inserting the paper tape Inserting the tape into the puncher Using the capstan to transport the paper The paper tape leaving the machine at the left
Fialka M-125-3 with the paper tape feeder fitted at the back Releasing the retaining bracket Releasing the retaining bracket for installing a fresh paper reel Paper break Paper guide Paper guide
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Reverse side of the paper feeder (i.e. the side that faces the rear of the Fialka)
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Paper tape feeder with a partly used paper reel installed
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Accessories stored inside the dust cover
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The paper tape holder, or paper tape supply reel.
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Installing the paper feeder
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Fitting that mates with the metal stub at the rear of Fialka
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Metal stub for holding paper feeder at the rear of the Fialka
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Paper tape feeder mounted at the back of the Fialka
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The paper feeder mounted at the rear of the machine
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Preparing the paper tape
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Inserting the tape from the rear, so that it exits at the right
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Pulling the paper through the hole at the right
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Re-inserting the paper tape
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Inserting the tape into the puncher
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Using the capstan to transport the paper
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The paper tape leaving the machine at the left
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Fialka M-125-3 with the paper tape feeder fitted at the back
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Releasing the retaining bracket
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Releasing the retaining bracket for installing a fresh paper reel
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Paper break
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Paper guide
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Paper guide

Crank
Each Fialka machine is supplied with a small hand crank that is usually stored inside the dust cover, in the corner behind the paper tape feeder. The crank is made of hardened steel and has a bakelite grip.

It can be inserted into a hole in the right side of the body of the machine where it is engaged with the main non-ratating driving axle. It can be used to advance or step-back the position of the wheels as part of the operating procedures or for the correction of mistakes.
  
The hand crank

The crank, stored inside the dust cover The hand crank Another view of the crank The hand crank The hand crank inserted into the hole at the right Operating the hand crank
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The crank, stored inside the dust cover
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The hand crank
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Another view of the crank
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The hand crank
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The hand crank inserted into the hole at the right
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Operating the hand crank

Print heads
The print head used in the Fialka has two rings of letters, which can be used for a variety of character sets and combinations. The print head lift, that is part of the printer, determines which ring is used. In its normal position, the lower ring of letters is used, but when an alternative alphabet is selected, the print head is raised, so that the lower ring is used instead.

The most commonly used print head is normally mounted in the machine, whilst one or two spare print heads are stored inside the dust cover, where they are mounted on the same shaft as the Test Reflector. The print heads are protected by small white plastic caps as shown here.

In the machine shown here, the Polish (Latin) print head with punctuation marks is mounted in the machine, where it is used for the machine's Mixed Character Mode. Two spare print heads are supplied: one for Mixed Mode Russian and one for simple Latin (Text Mode set to Б).
  
Unpacking a print head

Depending on the country and the purpose for which the machine was issued, different print heads may have been supplied, such as a single-ring Cyrillic-only variant that was used for typing simple letters-only Russian with the Text Mode Selector set to Б (Letters). This mode was used for backwards compatibility with the older M-125 machines.

Most M-125-3 machines were used in Mixed Mode, to that letters, numbers and punctuation marks could be mixed freely, by using the (A...) and (1...) keys to toggle between letters and numbers. As the M-125-3 did not support a combined Cyrillic/Latin print head, a separate 2-ring Cyrillic print head had to be installed for writing messages in Russian. This was the common way to exchange messages between the Warsaw Pact countries.

Removing the retaining clip from the shaft Removing the print heads from the shaft Two print heads in their protective cover Unpacking a print head Mixed Mode Russian print head Close-up of the Mixed Mode Russian print head Simple Latin print head Close-up of the simple Latin print head
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Removing the retaining clip from the shaft
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Removing the print heads from the shaft
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Two print heads in their protective cover
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Unpacking a print head
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Mixed Mode Russian print head
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Close-up of the Mixed Mode Russian print head
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Simple Latin print head
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Close-up of the simple Latin print head

Test reflector
As a troubleshooting aid for a malfunctioning machine, a test reflector was supplied that could be mounted instead of the cipher wheels, effectively eliminating the wheels. The test reflector was usually stored on a small axle inside the dust cover and was held in place by a retaining clip.

In order to use the test reflector, two retaining clips are needed: the one that was used to retain it inside the dust cover and the one that normally retains the wheels on the spindle.

Especially for use of the test reflector, the spindle has an extra rig engraved towards the right. The tet reflector is placed between the two rigs and held in place by the two retaining clips. The spindle is then mounted inside the machine in the usual manner, as shown in the image on the right. The white line of the test reflector has to line up with the white dot on the entry disc.
  
Test reflector mounted inside the machine

The test reflector connects the contacts of the entry disc together in pairs: 1-2, 3-4, 5-6, etc., and effectively eliminates the cipher wheels and the reflector from the cryptographic algorithm. When the machine is set to Coding or Decoding Mode (the MODE selector in the 'З' or 'Р' position) and the metal test triangle is placed in the card reader, it is now possible to trace the electric current from each key through the card reader, the entry disc and back, through to the printer.

Wiring of the test reflector Extra rig in the spindle used for the test reflector Spindle, test reflector and two retaining clips Test reflector mounted on the spindle Placing the test reflector inside the machine Test reflector mounted inside the machine Aligning the test reflector M-125 with test reflector in place
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Wiring of the test reflector
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Extra rig in the spindle used for the test reflector
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Spindle, test reflector and two retaining clips
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Test reflector mounted on the spindle
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Placing the test reflector inside the machine
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Test reflector mounted inside the machine
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Aligning the test reflector
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M-125 with test reflector in place

Spare wheels
Each Fialka machine came with two full sets of rotors: an operational one that resided in the machine, and a spare one that was stored in an aluminium can. In order to distinguise between the two sets, the letters on the rim of the operational set were painted in black, whilst the letters on the spare set were red. The letter identifying the wheel was painted in the alternative colour.

The image on the right shows a complete spare set as it was supplied with the Polish variant of the M-125-3. The wheels have red lettering with one letter (the letter identifying the wheel) in black. The wheels all have identical serial numbers (in this case: 1391) with a '3K' prefix, indicating that the wheel have Polish wiring.

The spare wheels were normally stored in a aluminium container that was kept inside the metal dust cover, where it was retained by a metal strip. The red wheels would only be used in case the operational wheels were broken or needed maintenance, which is why the quality of the red wheels is often better.
  
Spare wheel set in aluminium can

The spare wheels were wired identically to the operational ones so that they could be used immediately in case of an emergency. When not in use, the wheels were all set to their basic position (i.e. the rings set to 'A' and the cores with side '1' up) and were placed on the spindle in the order of the alphabet, so that no information about a previous key was revealed.

Having a spare wheel set was also useful in case the cryptographic key was changed more often (e.g. twice each day). It allows one set to be prepared for the new key well in advance, so that it can be swapped quickly. This minimises the time the machine is 'off-line'.

 The wheels in more detail

Aluminium can with spare wheel set Aluminium can with spare wheel set Spare wheel set in aluminium can Spare wheel set in aluminium can Spare wheels taken from the spindle Frontal view of the spare wheel set Operational wheel set with black lettering Close-up of the spare wheel set
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Aluminium can with spare wheel set
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Aluminium can with spare wheel set
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Spare wheel set in aluminium can
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Spare wheel set in aluminium can
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Spare wheels taken from the spindle
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Frontal view of the spare wheel set
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Operational wheel set with black lettering
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Close-up of the spare wheel set

Toolkit
Each Fialka machine was supplied with a toolkit that was used for daily maintenance and small repairs. The toolkit consisted of an (army) green canvas wallet with several screwdrivers, wrenches, pins and hooks.

Although a toolkit was supplied with every machine, not many of them have survived, making them into desired collector's items.

 More information
  
Picking one of the tools

Spares kit
In addition to the toolkit, the Fialka was also supplied with a small wooden box with spare parts and accessories, or in Russian: Запасные части И Принадлежности, or ЗИП (Latin: ZIP).

The spares kit contains mechanical, electrical and electronic parts, a tape moisturizer, a spare axle, retaining clips and much more.

 More information
  
Fialka ZIP box with the lid taken off

Oil can
Apart from the toolkit, an oil can was supplied for maintenance. It was used to oil the moving parts of the machine, such as the axles, the bearings and the rotor spindle.

The image on the right shows the oil can that was supplied with each Fialka machine.

 More information
  
Fialka oil can

User manual
Each country of the Warsaw Pact had its own version of the User Manual, written in the local language. The manual explained the operation of the M-125-3, its maintanance and the cipher procedures to be followed.

The image on the right shows the East-German version of this manual, which was known in the DDR as A 040/1/321 [1].
  
M-125-3 with the German (DDR) version of the manual

M-125-3 with the German (DDR) version of the manual German (DDR) version of the instruction manual First page of the German manual Example of key material in the German manual The toolkit in front of an M-125-3 Picking one of the tools Using the hook to replace a spring Fialka oil can
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M-125-3 with the German (DDR) version of the manual
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German (DDR) version of the instruction manual
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First page of the German manual
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Example of key material in the German manual
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The toolkit in front of an M-125-3
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Picking one of the tools
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Using the hook to replace a spring
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Fialka oil can

Standard PSU
The image on the right shows the standard PSU, of which two manufacturing variants exist. It is the most common PSU that was used with Fialka machine and was also issued with the later M-105 (Agat) cipher machine.

The standard PSU allowed the Fialka machine to be powered from a wide range of mains AC voltages as well as from a 24V DC network.

 More information
  
Standard Fialka PSU. Click for more information.

Tempest PSU
Polish Fialka machines (M-125-3MR2) were issued with a very sophisticated stabilized Power Supply Unit (PSU) that contained extra circuitry to improve overall cipher security by adding extra TEMPEST measures.

 More information
  
Advanced Fialka PSU with TEMPEST feature. Click for more information.

Service lamp
For setting up a Fialka machine in the dark and for maintenance and repair, a small 24V service lamp was supplied as part of the spares kit (ZIP). It consisted of a bakelite grip, a metal reflector and a 24V car lamp. At the end of the cable was a 2-pin plug, similar to a mains wall plug (which is probably why so many lamps are broken).

The service lamp was connected to the 24V outlet of the Fialka PSU, either 'piggy backed' to the Fialka power cable of the standard PSU, or to the dedicated socket of the Tempest PSU.
  
24V service lamp with cable and plug

Fialka service lamp as it was stored Fialka service lamp 24V service lamp with cable and plug Holding the service lamp Close-up of the reflector Service lamp connected to the standard PSU by inserting it 'piggy back' to the Fialka power cable Using the service lamp Connecting a work-light to the rear of the PSU
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Fialka service lamp as it was stored
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Fialka service lamp
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24V service lamp with cable and plug
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Holding the service lamp
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Close-up of the reflector
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Service lamp connected to the standard PSU by inserting it 'piggy back' to the Fialka power cable
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Using the service lamp
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Connecting a work-light to the rear of the PSU

Test triangle
Each Fialka machine was issued a thin metal triangle that could be placed in the drawer of the card reader, instead of the key card. At the end of the day or session, the Fialka was set to its basic position and the key card was removed and destroyed.

The metal triangle was then placed in the card reader. It forces the identity matrix (A → A), so that the machine can be used in plain text Mode.

 The test triangle in more detail
  
Placing the test triangle in the card reader

The metal test triangle for the Fialka card reader Holding the metal test triangle Holding the metal test triangle Close-up of the upper edge of the test triangle The text BEPX (this side up) at the upper edge of the triangle Placing the test triangle in the card reader Test-triangle in the drawer of the card reader, creating the 'unity matrix' Close-up of the test triangle in the card reader
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The metal test triangle for the Fialka card reader
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Holding the metal test triangle
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Holding the metal test triangle
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Close-up of the upper edge of the test triangle
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The text BEPX (this side up) at the upper edge of the triangle
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Placing the test triangle in the card reader
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Test-triangle in the drawer of the card reader, creating the 'unity matrix'
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Close-up of the test triangle in the card reader

Wheel opener
When setting the daily key it is necessary to open each wheel, remove the core and re-install another core with the correct orientation and start position. Furthermore, the wheel also had to be opened in order to change the ring setting.

This is done by removing the metal disc at the center of the wheel manually, by pressing and rotating the disc, or with the help of the special Fialka wheel opener shown in the image on the right. The opener consists of an aluminium tool with three hardened pins at the botton, that line up with the three holes in the metal disc.

 More about opening the wheels
  
Opening a wheel with a special tool

Fialka cipher wheel with special opener Opening a wheel with a special tool The wiring core removed from the wheel Wiring core removed from the wheel
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Fialka cipher wheel with special opener
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Opening a wheel with a special tool
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The wiring core removed from the wheel
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Wiring core removed from the wheel
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Tape moisturizer
In some cases the Fialka was used to print the decoded output directly to narrow pre-gummed 10 mm paper tape, so that the message could be glued on to a message form, just like a telegram.

In such cases the tool shown in the image on the right was used to moisterize the pre-gummed tape in order to activate the glue.

 The tape moisturizer in more detail
  
Narrow tape moisturizer

Spare parts
In addition to the Spare Parts and Accessories Box (ZIP) shown above, various other parts and building blocks were available for an authorised repair centre.

Apart from the usual mechanical, electrical and electronic components, complete building blocks were available, such as the 5-bit encoder diode matrix, the puncher driver and the famous magic circuit.
  
A collection of Fialka spare parts taken from the ZIP

A collection of Fialka spare parts taken from the ZIP Close-up of some spare parts Transistor for the puncher driver Bottom view of the magic circuit (new version) Top view of the magic circuit (new version) Puncher driver (top view) Diode matrix (contact side) Diode matrix (5-bit encoder)
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A collection of Fialka spare parts taken from the ZIP
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Close-up of some spare parts
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Transistor for the puncher driver
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Bottom view of the magic circuit (new version)
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Top view of the magic circuit (new version)
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Puncher driver (top view)
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Diode matrix (contact side)
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Diode matrix (5-bit encoder)

M-125-3MR2 Polish variant
The M-125-3MR2 (Russian: М-125-3МР2) was the version of the M-125-3 that was used in Poland during the Cold War. The machines were given on a lend/lease contract with the USSR (Russia) from the early 1960s onwards, until the fall of the Soviet Union in 1992.

The image on the right shows the Polish variant of the M-125-3. It had a specific Polish layout of the Latin characters on the keyboard plus some typical Polish letters, and a country-specific print head. Furthermore, the wheels had a country-specific wiring that was identified by the engraved prefix 3K on each wheel.

 More about the Polish variant
  
Polish Fialka machine with TEMPEST power supply unit (PSU)

M-125-3MR3 Czech variant
The M-125-3MR3 was the version of the M-125-3 that was used in Czechoslovakia during the Cold War. The machines were given on a lend/lease contract with the USSR (Russia) from the early 1960s onwards, until the fall of the Soviet Union in 1992, after which they had to be destroyed.

Destruction took place between the late 1990s and the early 2000s. Most of the machines were damaged by smashing them with a hammer and some were even burned. Like in Poland however, some machine miraculously survived demolition and in some cases collectors were able to rebuild complete Fialkas from the demolished remains.

The image on the right shows an M-125-3MN, which is the Czech variant of the M-125-3. It is electrically identical to the Polish variant, but has a different keyboard layout, a different print head and differently wired cipher wheels (6K).

 More about the Czech variant
  
Czech Fialka with standard PSU

M-125-3 Hungarian variant
So far, no surviving sample of an Hungarian Fialka machine has been discovered. However, during one of our tripts through Europe we found a complete set of Hungarian (5K) cipher wheels of which we have traced the wiring.

 More about the Hungarian variant
  
Aluminium container and 5K wheels

M-125-3M Russian variant
Recently (2013) an original Russian M-125-M has popped up. The machine was given to a former KGB sniper on his retirement. The machine is an exception to the rule that all M-125-3 models had square keys. The M-125-3 shown here has rounded keys, as it has no support for the Latin alphabet.

Unfortunately, the original 1K wheels were missing, so the wiring of these wheels will remain a mystery for now.

 More about the Russian variant
  
Frontal view of the M-125-3M

M-125-3MN DDR variant
As far as we currently know there are no surviving examples of the Fialka variant that was used in the former DDR (East-Germany). Following the reunification of Germany, all machines were delivered back to the Russians and have subsequently been destroyed.

As a result, we do not know the wheel wiring, but from a surviving manual we know the full keyboard layout.

 More about the DDR variant
  

5-level paper tape
The M-125 can read and punch standard 5-level paper tape, just like many western telegraphic devices of the era, but uses neither the standard Baudot encoding nor its Russian variant for this. Instead, the machine uses a proprietary encoding that was only used for Fialka and for the later M-105 (AGAT) one-time tape machine. The 5-bit alphabet is illustrated in this diagram:

Proprietary encoding scheme used for 5-level punched paper tape

With 5 holes it is possible to create 25 = 32 different combinations. 30 of these are used for the standard 30 characters that are available on the keyboard. The two ramaining positions are taken by the SPACE character (10001) and the NULL character (00000), which is also known as STOP.

Block diagram
Although the circuit diagram of the M-125-3 is much more complex than that of its predecessor, the M-125, its operating principle is identical. Please refer to the description of the block diagram of the M-125 for a more complete explanation. The extra complexity is added for the 30 ↔ 10 reduction switch (NumLock). The block diagram below shows the various parts of the M-125.

Block diagram of the M-125

The keyboard at the right is used for the input. It consists of 30 contacts; one for each key. Furthermore, the keys are mechanically encoded into a 5-bit digital code (similar to Baudot). When typing, the current from the 30 contacts is passed through the card reader at the top right onto a static entry disc. From there, it passes through the 10 cipher wheels until it hits the reflector at the left. The reflector returns the current through the cipher wheels, the entry disc and the card reader, until it arrives at the electronic 5-bit encoder that drives the printer.

 Block diagram in more detail

Magic Circuit
The use of a reflector makes the machine symmetrical, which means that the same settings can be used for encoding and decoding. A major drawback however, is that a letter can never be encoded into itself. This was considered a serious weakness of the Enigma cipher machine.

In the Fialka, this is solved by adding a clever electronic circuit to the reflector, to ensure that a letter can be encoded into itself. This is done by taking 4 wires out of the reflector (i.e. two pairs). One of these wires is used as the 'letter-can-be-itself' signal and is sent back to the keyboard. The remaining three wires are combined into a binary rotator. In the German Fialka literature, this circuit is called Dreipunkschaltung (three-point circuit), but we have dubbed it 'Magic Circuit'.

Reversing the direction of the binary rotator by swapping two lines

The effect of the Magic Circuit is that each letter has a 1:30 chance of being encoded into any other letter, making the machine cryptographically stronger than the Enigma. A side-effect of the binary rotator however, is the the machine is no longer fully symmetrical. This is solved by adding a Mode Switch (coding/decoding) that simply swaps two of three lines of the binary rotator.

 More about the Magic Circuit

30 ↔ 10 Reduction Switch   NumLock
In the M-125-3 the situation at the reflector is even more complex as it is also connected to the 30 ↔ 10 reduction switch. In normal use (i.e. when the switch is set to the '30' position), the machine can be used to encrypt and decrypt letters, and the reflector is wired as in the M-125.

Block diagram of the M-125-3

When the switch is set to the '10' position, 20 contacts from the reflector are routed back to the input of the card reader. At the same time, the number of contacts from the keyboard is reduced from 30 to 10. In this mode, only numbers can be entered. The remaining keys are blocked.

The cover removed from the machine

Interior
The interior of the M-125-3 can easily be accessed by loosening two large bolts in the top of the cover (one is accessible through a hole in the top lid), and a small screw at the front, just below the keyboard. After that, the cover can lifted upwards, revealing the complex interior. The images below should give a good impression of the various parts of this extemely well-built machine.




The machine can roughly be divided into three sections: the keyboard at the front, the cipher wheels at the centre and the printer/puncher at the rear. The card reader is hidden underneath the cipher wheels and is accessible via a drawer at the left. Alhough the machine has a highly modular construction, the various parts are mechanically intertwined in several areas.

All parts are mounted to the base plate (i.e. the bottom shell of the machine), which acts as a reference for the mechanical adjustment of some parts. Some axles and pawls are permanently fitted to the base plate to act as a mechanical interface between certain parts of the machine.

The electrical timing of the machine is generated by an interruptor contact at the left side of the machine, close to the main spindle. This contact is actuated by a notched disc that is driven by the main motor axle. This pulse also acts as the STROBE for the digital 5-bit data output.
  
Printer/puncher mechanism

At the front of the machine is the keyboard, which has a complex mechanical structure of metal arms, pawls and rods underneath the keys. Each key actuates one of the contacts of an array of switches that is mounted behind the keyboard. The rods below the keys are also used to mechanically generate a 5-bit digital code. The code is converted into electrical signals by means of 5 switches that are mounted in a small metal enclosure to the left of the keyboard.

To the right of the keyboard is the tape reader that is mechanically coupled to the keyboard. It directly drives the 5 rods underneath the keyboard, in such a manner that it mimics the operation of the keyboard. This means that it drives the 30 individual key contacts as well as the 5-bit encoder to the left of the keyboard.

The tape reader is driven by an axle that is part of the base plate assembly. When the user presses the green START key (ПУСК), the tape reader is coupled to this axle and starts reading the paper tape that is inserted at the front.
  
Close-up of the tape reader mechanism

The tape runs until the user presses the STOP key (СТОП) or a NULL character is encountered on the tape (00000), at which point the tape reader will be decoupled from the driving axle. The alignment of the tape reader is extremely critical and many of the adjustment are sealed (yellow).

The center part of the machine is taken by the wheel stepping mechanism, which becomes visible after removing the drum (i.e. the spindle with the 10 cipher wheels). It consists of two sets of transport-combs: the upper one for the stepping of the odd cipher wheels and the lower one for the stepping of the even cipher wheels.

When the motor is running, this mechanism is at rest, but as soon as a key is pressed, it is mechanically coupled to the main driving axle, causing a single step of the wheels. After one full revolution of the axle, it is decoupled again.
  
The wheel stepping mechanism at the heart of the machine

Wheels 2 and 9 are advanced on each key press. The short metal pins at the other rim of the wheels (sometimes referred to as the notches) control the stepping of the over-next wheel. The presence of a pin inhibits the stepping of the wheel two places further. In other words: wheel 2 controls the stepping of wheel 4, wheel 4 controls the stepping of wheel 6, and so on.

If a pin is absent on one wheel, the wheel two places further will also make a step when a key is pressed. Of the odd wheels, wheel 9 controls the stepping of wheel 7, wheel 7 controls the stepping of wheel 5, 5 controls 3 and so on.

The output of the machine is available in three different streams: as a punched paper tape, in printed form and as digital signals, all of which is controlled by the printer/puncher mechnism at the rear right. The printer is driven by the output of a diode matrix that converts the 30 output lines into a 5-bit digital data signal.
  
Printer/puncher mechanism seen from the rear

The diode matrix itself is hidden in the bottom section of the machine, below the mechanical parts. The 5-bit data signal is used to drive 5 solenoids that are located in a metal enclosure at the back of the printer/puncher mechanism. The solenoids in turn drive the five punchers of the tape puncher and also control the point at which the hammer of the printer is released.

In addition to this, the output is also available electrically from the brown 10-pin socket at the right rear of the machine. This signal can be used to drive external telegraphic equipment directly. It can also be used for transmission by connecting the R-590A (Rus: Р-590А) interface.

When the machine was used in combination with the advanced Power Supply Unit (PSU), which was the case in Poland, this output is used to drive the Electronic Counter Measures that are present in the PSU. It prevents an eavesdropper from obtaining information by tapping the power line.
  
Two connectors at the left rear

At the left rear of the machine, just below the power section, are two rather strange connectors: a big one and a smaller one, as shown in the image above. The smaller one is held in place by two screws and was used to convert the machine into a Latin-only machine by reversing the plug. 1 The wider plug was used for the connection of a test device and can be accessed through a hole in left side of the machine's cover. It contains a number of shorting wires and must be present.

The machine is mechanically driven by a 24V DC motor, which is located at the rear left of the machine. The image on the right shows the rear of the machine with the grey motor at the right.

When the machine is switched ON, the motor runs continuously until it is switched OFF again. If a machine hasn't been used for some time, it is possible that the grease has dried up, preventing the motor from starting. In such cases it might help to rotate the kurdled knob at the bottom centre in the direction of the arrow. Ensure that the machine is off when you do this.
  
Rear view of the interior of the M-125-3


  1. The small configuration plug at the left rear could be inserted in two positions: Russian and Latin. It was normally placed in the Russian position. When reversed (i.e. in the Latin position) it reduced the number of characters from 30 to 26, by looping 4 lines from the reflector back to the entry wheel. There is no evidence however, that the machine was ever used in this 'Latin-only' configuration.

Removing the cover (1) Removing the cover (2) Removing the cover (3) Cover removed from the M-125-3 M-125-3 interior seen from the rear right Fialka interior seen from the rear left Fialka interior seen from the front left M-125-3 interior seen from the front right
Rear view of the interior of the M-125-3 Printer/puncher mechanism Printer/puncher mechanism seen from the rear Clear view of the wheel stepping 'fingers'. Note the (yellow sealed) adjustment screws at the left and right. Leftmost adjustment screw for the front set of fingers (even wheels) Rightmost adjustment screw for the rear set of fingers (odd wheels) Vertical lever that is used to select the required character set Two connectors at the left rear
Character counter and pulse mechanism Timing pulse interruptor Printer/puncher input connector Close-up of the tape reader mechanism Operating the transmit lever of the tape reader Keyboard 5-bit code connector The wheel stepping mechanism at the heart of the machine Close-up of the wheel-stepping combs
Close-up of the entry disc Close-up of the reflector 5-letter group lever The power section and the ink ribbon. At the right is the printer head. Close-up of the printer Top view of the keyboard after the cover has been taken off
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Removing the cover (1)
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Removing the cover (2)
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Removing the cover (3)
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Cover removed from the M-125-3
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M-125-3 interior seen from the rear right
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Fialka interior seen from the rear left
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Fialka interior seen from the front left
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M-125-3 interior seen from the front right
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Rear view of the interior of the M-125-3
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Printer/puncher mechanism
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Printer/puncher mechanism seen from the rear
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Clear view of the wheel stepping 'fingers'. Note the (yellow sealed) adjustment screws at the left and right.
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Leftmost adjustment screw for the front set of fingers (even wheels)
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Rightmost adjustment screw for the rear set of fingers (odd wheels)
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Vertical lever that is used to select the required character set
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Two connectors at the left rear
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Character counter and pulse mechanism
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Timing pulse interruptor
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Printer/puncher input connector
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Close-up of the tape reader mechanism
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Operating the transmit lever of the tape reader
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Keyboard 5-bit code connector
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The wheel stepping mechanism at the heart of the machine
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Close-up of the wheel-stepping combs
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Close-up of the entry disc
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Close-up of the reflector
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5-letter group lever
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The power section and the ink ribbon. At the right is the printer head.
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Close-up of the printer
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Top view of the keyboard after the cover has been taken off

Wheel stepping alignment
After many years of service it is quite possible that the machine's wheel stepping mechanism needs re-aligning. This may also be necessary after a machine has been 'sanitised' or has been involved in an 'accident'. If one or more wheels at one end of the drum are sticking or are not stepping as expected, it may be necessary to readjust the angle of the stepping mechanism.

Location of the adjustment screws. Click for a better view.

Re-alignment of the angle of the transport combs is possible with the adjustment screws at either side of the drum. They are marked with a yellow circle in the diagram above. Do not alter any of the other adjustment screws and always make a note or a photograph of their current position.

As you can see in the image on the right, each of the adjustments consists of two screws that are normally sealed (yellow in this case). Release the larger of the two screws (just loosen it a bit) and then adjust the smaller one to the desired hight. Then fixate the larger one again. If necessary, do this with the rightmost adjustement screws too.

The leftmost adjustment alters the angle of the front transport comb, which affects the stepping of the even wheels. Likewise, the rightmost adjustment alters the angle of the rear transport comb, which affects the odd wheels stepping.
  
Leftmost adjustment screw for the front set of fingers (even wheels)

You may have to repeat the above procedure a couple of times to achieve the desired result. If it doesn't solve the problem, it is possible that one of the axles is bended or that the fingers have been damaged. It that case it may be necessary to repair or replace certain components.

Clear view of the wheel stepping 'fingers'. Note the (yellow sealed) adjustment screws at the left and right. Leftmost adjustment screw for the front set of fingers (even wheels) Rightmost adjustment screw for the rear set of fingers (odd wheels)
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Clear view of the wheel stepping 'fingers'. Note the (yellow sealed) adjustment screws at the left and right.
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Leftmost adjustment screw for the front set of fingers (even wheels)
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Rightmost adjustment screw for the rear set of fingers (odd wheels)

Test socket
The M-125-3 has a special test socket marked Ш2 at the left rear, below the 24 DC input socket. This test socket allows various parts of the machine to be tested without getting access to the interior. The 24-pin socket was probably used for the connection of a dedicated test device that provided some level of diagnostics. This test socket is not present on the earlier M-125.

24-pin test socket and shorting plug.

In normal use, a shorting plug should be present in the test socket. It is held in place by two curdled screw terminals. The shorting plug contains several wire bridges that connect the various building blocks of the machine together. Without this plug, the machine will not run.

 More about the test socket

Positions of the serial number
The serial number of the Fialka was printed on a small serial-number badge that was mounted at the front of the machine, just below the keyboard. Unfortunately, this badge has been removed from most machines as part of the demilitarization process. Nevertheless it is possible to retrieve the serial number of a machine, as it is engraved in a number of parts inside the machine as well. The following locations are known:

  1. This requires the machine to be opened (i.e. remove the top cover).

Front of the machine (with dust cover in place) Serial number at the lower front of the machine At the right side of the drum mechanism On the hinge inside the top lid Below the keyboard Bottom of the puncher at the right side of the machine Serial number engraved in the base of the motor Installing the paper feeder
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Front of the machine (with dust cover in place)
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Serial number at the lower front of the machine
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At the right side of the drum mechanism
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On the hinge inside the top lid
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Below the keyboard
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Bottom of the puncher at the right side of the machine
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Serial number engraved in the base of the motor
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Installing the paper feeder

Older version
Before the M-125-3 was introduced in the mid-1960s, its predecessor, the M-125 was used. It can easily be distinguished from the M-125-3 as its keyboard has rounded key tops whereas the key on the later machine are square. Furthermore it only has two letters on each key: a Cryllic one (in black) and a Latin one (in red). Furthermore these machines were issued with the standard (non-adjustable) cipher wheels.

 More information about the older M-125.

The older M-125 and the later M-125-3 side by side (Polish versions shown here)


References
  1. Jörg Drobick, Nutzung der Fialka M-125
    Website: Der SAS- und Chiffrierdienst (SCD). Retrieved May 2014.

  2. Paul Reuvers and Marc Simons, The Fialka M-125 Reference Manual
    Copyright 2005-2009. Version 2.0, June 2009. ISBN 978-90-79991-01-3.
Further information
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Crypto Museum. Created: Monday 12 May 2014. Last changed: Tuesday, 13 June 2017 - 20:24 CET.
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