Reparing a power supply 82002A

[hibiki]

Hi all ! I am new in the forum. My First post.

Hi Xavier ! I am an electronic technician and will try to help you with some hints.

If you have a multimeter, the first step is check the transformer coils continuity. The primaries coils should not present infinite resistance between their terminal wires. The same for the secondary coil (lower resistance). If some of them are open circuit, you should replace the transformer.

According to the schematic seen in the Van der Sander page, check if your power supply has a fuse that could be open due to the overvoltage applied. If it is ok, check the voltage rating marked in the capacitor C1 of 400uF and if it is intact (not blown, electrolitic capacitors do not support overvoltage applied, but nevertheless, it can be replaced as its age is very old). The diodes 1N4002 are rated 100V reverse voltage and 1A of current, so they should be ok. Other parts that could be damaged are the zener diode D5 and transistor Q1. It is and old form of voltage regulator, that is better replaced with a 7805 ic regulator plus a diode in series to supply the 4.2Vdc.

But if you could post some pictures/photos we could give you better advices.