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Standard PSU
Fialka power supply unit

As far as we know, two different power supply units have been used in combination with the Fialka cipher machine. One is a rather simple variant, whilst the other one contains advanced counter measures against the exploitation of unwanted eminations (also known as TEMPEST).
 
The one shown here is the standard variant of which the model number is currently unknown. It was supplied with the Fialka cipher machine in most countries of the Warsaw Pact, including East Germany (DDR) and Czechoslovakia. It was also supplied with the later M-105 (Agat).

The standard Power Supply Unit (PSU) measures 26 x 17 x 17 cm and was designed for use with cipher machines that were driven by a 24V DC motor. It allows them to be powered from the AC mains and supports a wide range of AC voltages (90-260V) in steps of approx. 10-30V.
  
Standard PSU

All connections and controls are located at the control panel at the top of the device, which is normally covered by a hinged top lid. The layout of the control panel is rather cluttered and in some respects confusing. The choice of connectors and sockets is potentially dangerous and may cause permanent damage when they are not used properly. Two versions of this PSU are known: an older one with a separate power selector and ON/OFF switch and a new one where the ON/OFF switch is combined with the power selector. Both variants are shown in the images on this page.
 
The standard PSU with the top lid closed Standard PSU for M-125 (Fialka) and M-105 (Agat) Standard PSU Standard PSU control panel Close-up of the front panel with the two main cables connected PSU with open lid seen from the front The five cables in front of the PSU Standard PSU with AC mains cable and 24V DC cable

 
Versions
So far, we have encountered two slightly different versions of the standard PSU:
 
  • Older version with separate ON/OFF switch
    On the older version of the PSU, a separate ON/OFF switch is present. It is located to the left of the mains voltage selector at the bottom right of the control panel. Furthermore, the text on the control panel is printed in a large - rather fat - typeface. This version generally has a 5-digit serial number that is printed on the top lid of the case.

  • Newer version with combined ON/OFF switch
    On a later version of the PSU, the ON/OFF switch is combined with the AC voltage selector. In the leftmost setting of this selector, the PSU is switches OFF. Furthermore, the text on the control panel is printed in a smaller typeface and with some devices, the circuit diagram is printed inside the top lid. This version generally has a 7-digit serial number in the 98-xxxxx format.

Controls
The diagram below should help to understand the controls and connections of the PSU. They are not nicely arranged in a logical and safe manner, as one would expect with a device that is connected to the mains. At the top left is the socket for connection to the AC mains. The correct input voltage is selected with the 8-position rotary switch at the bottom right. On the later version of the PSU, this selector also functions as the ON/OFF switch. In the leftmost position, the PSU is switched OFF. The older version has a separate ON/OFF switch, to the left of the selector.

The PSU can also take its input from a 24V DC source, such as the battery of a (military) vehicle. If it is available, the 24V DC source is connected to the socket just below the mains socket at the top left. The toggle switch to the left of the meter at the bottom is used to select between them.


The 24V DC output voltage (i.e. the connection to the cipher machine) is available at the top right from the socket marked МАШИНА (Machine). The voltage can be fine tuned somewhat with the selector at the bottom left, whilst the meter at the bottom is used to monitor the correct voltage.
 
Mains AC input and 24V DC input 24V DC output and mains input voltage selector Fine-tuning of the 24V DC output voltage Input voltage selector and ON/OFF switch (old version) Meter for checking the correct output voltage (24V) 24V DC output socket and ground terminal Mains input and 24V DC input cables connected to the PSU Close-up of the front panel with the two main cables connected

 
Cables
Although the PSU is not a rare item (quite a few have survived destruction), finding the proper cables might present more of a problem as many of them have been destroyed after the units were taken out of service. Five cables were normally supplied with the PSU, but a minimum of two is needed to operate the machine. Luckily there are some sources for good reproduction cables. In the description below it is assumed that the PSU is used in combination with the M-125 Fialka cipher machine. For use with the M-105 Agat, a different set of cables might be needed.
 
When in transit, the cables were usually stored in the special cable compartment at the front of the PSU. The hinged lid of this compartment is held in place by two screws and can easily be opened by hand. A total of five cables were supplied with the PSU, as shown in the image on the right.

Be careful with these cables as they might have become fragile after all this time. Once you got them out of the storage compartment, it might be best to leave them out and store them separately with the PSU in the future. This will protect the cables against too much bending.
  
The five cables in front of the PSU

For safety reasons it is advised to thoroughly check the mains power cable before connecting it to the mains. As the cable is rather old, the insulation of the internal wires may have become brittle and might have to be replaced. Use the mains cable only if you are certain that it is safe.
 
A minimum of two cables are needed to connect the PSU to the mains and to the cipher machine. The mains cable has a standard wall plug at one end and a rather strange 3-pin female plug at the other end. Warning: be careful as the female contacts of this plug can be touched by hand.

Depending on the version, the wall plug of the mains cable might not fit a standard European wall socket. This is because the wall plugs in the East-European countries have thicker pins. Use an appropriate adapter or swap the wall plug for an approved one if you want to use the cable.
  
The 3-pin female plug for the mains connection

The 24V DC output cable has a Fialka power plug at one end and a rather strange 3-pin male plug at the other end. This plug mates with the 24V DC output socket at the top right of the PSU. Warning: never connect this 3-pin male plug (24V DC) to the 3-pin female plug (230V AC) of the mains cable. Due to bad design, it fits perfectly, but supplies the mains voltage to the 24V input of the cipher machine, causing permanent damage to the cipher machine. Be warned!
 
When present, the 24V DC input cable can be used to supply 24V from the battery of, say, a military truck, directly to the PSU. It allows switching between the AC mains and the DC battery voltage without swapping the cables.

The 24V DC input cable has a Fialka 24V plug at one end and a 2-pin plug at the other end. The Fialka 24V plug mates with the 24V DC input socket at the top left of the PSU, just below the mains socket. The other one should go to the 24V rail of the vehicle. It should be marked with (+) and (-) symbols. Be careful when connecting.
  
The 3-pin male plug for the 24V output connection

Also be careful not to put this 2-pin 24V plug into a mains wall socket. Although it fits perfectly, it is not intended for this. If a suitable 24V DC socket was not available in the vehicle, an extra battery cable could be used to connect this plug directly to a car battery or another 24V source.
 
The 24V DC input cable can also be used as an alternative power cable for the Fialka machine. It allows Fialka to be connected directly to the 24V rail of a vehicle or directly to a 24V battery.

It can also be used to connect an extra Fialka cipher machine to the PSU, simply by connecting it 'piggy-back' to the normal 24V output plug.

Please note that the PSU can only drive one machine at a time. The 'piggy-back' socket on top of the 3-pin 24V plug (see image) was normally used for connecting a service lamp.
  
Taking 24V DC power for an extra device

The last cable that was supplied with the PSU is a short ground wire. It allows the ground of the PSU to be connected to the ground of, say, a vehicle. If the PSU is placed on a metal surface (e.g. a table) the wire should be connected to this. The other end should be connected to the ground terminal (marked ЗЕМЛЯ) just below the 24V DC output. It was used as a safety measure.
 
The open cable compartment Close-up of the cables in the storage compartment The five cables in front of the PSU Mains AC cable 24V DC output cable (for connection of Fialka) 24V DC input cable (can also be used to power a second Fialka) Battery cable Ground wire
The minimum cable set needed to connect the PSU The 3-pin male plug for the 24V output connection The 3-pin female plug for the mains connection 24V DC output cable connected to the PSU Mains power plug Mains power plug with adapter The external 24V DC plug Using the service lamp

 
Using the PSU
The PSU can be placed anywhere near the cipher machine: either to the left, to the right, behind or above the machine, as long as the cables are long enough. It is important that the device has sufficient cooling and that the ventilation holes at the left and right side and at the top are not obstructed when the device is in use. For safety you might want to connect the ground wire.
 
When using the PSU for the first time, disconnect the cipher machine and check if the proper AC mains voltage is selected before connecting the PSU to the mains. Ensure that the power switch is in the OFF state. On old versions of the PSU this is done by setting the switch to the right of the meter (БКЛ. / БЫКЛ.) to the lower position.

On later versions of the PSU this is done by setting the voltage selector at the right to the leftmost position (БЫКЛ). Also ensure that the AC/DC selector (marked СЕТЬ~ / СЕТЬ–), to the left of the meter, is in the AC position (СЕТЬ~).
  
Input voltage selector and ON/OFF switch (old version)

Select the appropriate mains voltage. As the mains power in Europe is 230V in most countries now, it is best to set the selector to 250V. This avoids the transformer from going into saturation. On later versions of the PSU this automatically switches the PSU on, which ensures that the selected input voltage is never too high (and can damage the PSU) when the unit is turned on.
 
Connect the PSU to the mains by connecting the mains cable between the AC mains input socket at the top left and the AC mains wall socket. Now switch ON the PSU and check the reading of the meter. It should show approx. 24V DC.

If the voltage is higher or lower, you may correct it by changing the setting of the rotary selector at the bottom left of the PSU. Set it to МЕНЬШЕ (less) or ВОЛЬЕ (more) until the meter shows 24. If the meter doesn't show anyting at all at this stage, check the connections, the settings of the switches and the primary and secundary fuses.
  
Close-up of the meter showing a reading of 24V

Once the output voltage is confirmed at 24V, it is safe to connect the cipher machine. Ensure that the cipher machine itself is switched off and connect the 24V DC output cable between the 24V DC output socket at the top right of the PSU and the input of the Fialka cipher machine.
 
Now turn ON the cipher machine. At this stage, the motor of the cipher machine should start running. If it doesn't, there might be a special condition: the motor or the mechanism may be blocked (engine grease has dried up), or one of the fuses of the Fialka my have been blown.

If the machine has been OFF for a long time, it might help 'pushing' the mechanism a bit by rotating the knob at the rear of the Fialka mechanism manually. If the motor speed decreases when typing, it might help raising the DC voltage by a few volts: select ВОЛЬЕ (more).
  
The standard PSU connected to an M-125 Fialka machine

In situations where you have an option to choose between the AC mains and a 24V DC power source (such as the battery of a vehicle), it might be useful to connect the PSU to the 24V DC rail of the vehicle as well. Connect the 24V DC input cable to the 24V DC input socket of the PSU. The AC/DC selector can now be used to toggle between the two power sources. Set it to СЕТЬ– when using the 24V DC input, or to СЕТЬ~ for connection to the mains.
 
Input voltage selector and ON/OFF switch (old version) Input voltage selector with OFF position (new version) Meter for checking the correct output voltage (24V) Close-up of the meter showing a reading of 24V Fine-tuning of the 24V DC output voltage Mains AC input and 24V DC input The standard PSU connected to an M-125 Fialka machine Circuit diagram printed inside the top lid

 
M-105 (Agat)
Apart from the M-125 (Fialka), this PSU was also used in combination with the later M-105 (Agat) one-time-tape cipher machine. The description above for connection to the Fialka also applies to the Agat machine.

 More about the M-105
  
M-105 AGAT with 11-level key tape and normal 5-level tape loaded

 
Circuit description
The circuit diagram of the standard PSU isn't particularly 'rocket science' and doesn't provide any kind of voltage stabilization like the more advanced TEMPEST PSU does. The full circuit diagram is given below. It is also printed inside the top lid of the later version of the standard PSU. At the left is the AC input voltage selector that allows one of seven different taps of the primary side of the transformer to be selected. With the later variant this selector is also used as the ON/OFF switch.


The secundary side of the transformer has 7 different taps, allowing the secundary voltage to be adjusted somewhat, to cope with small variations in the mains power as well as variations in load. After rectification with D1-D4, the DC voltage is stabilized with an array of capacitors (C2-C5).
 
Connectors
The standard PSU has three sockets which are all located at the control panel at the top of the device, below the hinged top lid. Below is a specification of the pin-out of these sockets. The pinning of the sockets is given when looking into the sockets from the top of the device.


The 3-pin socket is for connection of the mains AC voltage. It is located at the top left of the control panel and accepts the mains AC cable. The 2-pin socket, just below it, is for connection of an external 24V DC source, such as the battery of a (military) vehicle. It accepts the 24V DC input cable. Ensure that the correct polarization is used by checking the (+) and (-) markings.

The 3-hole socket is for connection of the cipher machine. It is located at the top right of the control panel and accepts the 24V DC output cable. Ensure that the correct polarization is used. Also note that the pins of the mains socket and the 24V DC output socket are not evenly spaced, in order to prevent them from being inserted the wrong way around. Also note that the plugs of both cables (AC mains and 24V DC) mate with each other. DO NOT TRY THIS.
 
Interior
The interior of the PSU can easily be accessed by loosening the four large bolts in the corners of the control panel and using the two grips at the sides to pull the PSU out of its case. The transformer and all electric and electronic components are mounted to the rear of the front panel.
 
At the heart of the frame is a large transformer that has several primary and secundary taps that are routed to the two bakelite rotary selectors at the control panel. At either side are two of the four rectifier diodes, mounted in metal frames in order to obtain sufficient cooling. The wiring is nicely bundled, but there is no separation between primary and secundary wiring.

The image on the right shows the early model of the standard PSU. In this version the stabilisation capacitors (C2-C5) are missing, resulting in a less stable 24V DC output than the later version.
  
Interior of the standard PSU

The device is constructed in such a way that the air can easily flow through the case, using the grids at the sides of the case as inlets. The large black grid at the center of the control panel acts as the air outlet. In normal use, the transformer should not get too hot, but in areas where the mains voltage exceeds the maximum rating of the device, the transformer could run hot.
 
Loosening the large bolts in the corners of the control panel Pulling the frame out of the case The PSU frame outside its case Interior of the standard PSU Interior of the standard PSU (upside down) Wiring of the AC mains voltage selector Wiring detail Rectifier diodes

 
Glossary
AC   Alternating Current

DC   Direct Current

PSU   Power Supply Unit

Further information

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Crypto Museum. Created: Monday 12 May 2014. Last changed: Monday, 12 October 2015 - 14:46 CET.
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