When installing, be sure to observe polarity

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After repair, check that the tracks are not accidentally shorted with solder.

If so, it should be carefully scraped off with a sharp object (solder is soft, a knife or scalpel will do the job). Then wipe the area with alcohol and, if possible, cover with insulating varnish.

Capacitors
Worn capacitors swell. If there are any, feel free to change them. When they appear to be working, use an ohmmeter to check for short circuits. It is advisable to use a device to check the capacity, but then the capacitors will have to be unsoldered and soldered back. If the resistance is zero, the part is faulty.

But first, short-circuit the terminals with wire to ensure discharge. By the way, capacitors are the most likely to fail.


And it’s better to take a high-quality photo of the board before repairing it – to prevent problems in the future.

Resistors
To check, you usually don't need to unsolder them. Measure the canada telegram data resistance with a tester or ohmmeter. Then compare it with the declared one, which can be determined by the color marking of the resistor. If it doesn't match, the resistor needs to be replaced. It has no polarity.

Thyristor block
They have a variety - simistors. They are not fundamentally different. To check, you need to do the following.

Set the multimeter to a resistance measurement range of 2 kOhm for the highest voltage on the probes.
Connect the probes to the cathode and anode of the thyristor, observing the polarity (cathode - minus). The resistance should be infinite.
Connect the anode and the control electrode with a jumper. The resistance should drop sharply.
Remove the jumper. If the resistance again tends to infinity, the thyristor is working properly.
Checking the trigger status
To do this, measure the voltage between the input contacts. If it is less than 12 V, then the device is usually in good working order. To be sure, measure the resistance of the trigger filter. It should be 20 Ohm.