I got two old Soviet S1-94 (С1-94) Oscilloscopes which I use occasionally. However I noticed that they had increasing problems generating the high-voltage for the cathode ray tube (took a very long time to start up), as well as general jitter. I deduced that this is the most likely result of old soviet capacitors.
Recapping #1
This one was partially recapped by the previous owner. I also recapped some definitely broken capacitors beforehand but decided to also recap the rest now.
Recapping and Repair #2
My second unit is an older model with a DIN connector for the probe. This one stopped working at some point.
I also removed the fuses on the PCB and replaced them with modern ones, as those special sized soviet fuses are kind of hard to get and I have plenty of devices using them.
Disassembling the unit to actually get to all parts of the main circuit board is not that easy. The cathode ray tube socket is also not keyed, so care must be taken when taking this apart.
One of the drive transistors for the high-voltage supply was shorted out, so I replaced this with a modern BC type transistor. After fixing this issue it worked again!
