I recently picked up a IIgs System saver. I opened it up to see what it looked like on the inside and found that there are two resistors that seem to be running at too high of a wattage. They not only left burn marks on both sides of the PCB, but there is also a slight discoloring above them on the lid as well.
The heat damage also caused the pad to lift off the PCB when I took the resistor out to check it. These two resistors allow the LEDs to run directly off the mains. There are two LEDs in each switch, it looks like they installed them so they are also acting as a rectifier to generate the DC needed for the LEDs.
These resistors are dropping a lot of voltage. I measured somewhere in the neighborhood of 117vac across it. My mains are usually right around 120/121vac. The resistor colors are kind of hard to read, because I think the heat discolored them slightly. The resistors measured 7k ohms, but I suspect they are actually 6.8k ohms. Running that through Ohms Law, these resistors are dissipating around 2/2.1 watts. I can't say for sure if these are 2 or 3 watt resistors based on visuals alone. I sort of suspect these are 2w though. So I could put in a 3w metal film. But I think I may put in a 5w wire wound to give some more headroom.
Curious if by chance anyone else has opened up theirs, and noticed anything similar. And to maybe act as a warning to anyone else who has one that they may want to check. I mean, this thing hasn't started on fire in 30 some years. But still, better safe than sorry. This seems to be a poor design pushing parts to their limits.
I created an actual schematic of whats in there, if anyone is really curious. It's nothing too exciting. Just your standard EMI/RFI filter on the incoming power (inductor and a .47uF X2 safety cap across line/neutral), followed by 3 MOVs for surge protection (L-N, L-G, N-G), then the switches, resistors, and LEDs.