I recently got this east German Funkwerk Erfurt Stelltransformator 8600a, which is a 250VA step transformer with 14 steps and a ratio display.
Picture taken after the fixes outlined in this article
First thing I saw broken was the plug. The original one out of bakelite broke in an unrepairable manner. I replaced it with another bakelite plug I had sitting around.
Cleaning the inside
In order to cleanup the inside I completely disassembled and reassembled the unit. (Yes I fixed the cables on the right to look like they did before after taking this photo)
The resistor divider for the Sollwertanzeiger SWA1/2 (see below) is quite interesting, it consists of resistance wire. I measured it and the resistances are around 1-3Ω.
The Sollwertanzeiger SWA1/2 is basically two lamps in separate compartments. If both lamps (3.5V E10) have the same illumination, the value is as it should be.
|Uout > 220Vac|
|Uout < 220Vac|
I decided to redo the white paint on the knob, it was half way gone and quite yellow.