This is regarding the DE power supply for the small DMD games. I have someone asking me about this issue. Seems like a lot of people have had this problem and nobody has posted an answer. I've never run across it myself, but I know someone that has. The common problem described is that the 68v is low, usually about 20v low. People rebuild the PS or work on it and then R15 gets hot. Most people seem to give up and buy a new replacement board.
Okay, so they did shoddy work or installed something backwards, right? But why are so many people encountering this? Is everyone bunging up their boards in the same manner? Seems unlikely. Anyone know what is going on or what part is commonly installed incorrectly or is faulty and makes this happen? Is it a bad DMD causing the issue?
Some examples. Do a search on RGP for "hot R15" and you'll find four posts and no answer:
https://groups.google.com/forum/#!searchin/rec.games.pinball/hot$20r15
Some more searching will find even more cases with people asking about this with no answers.
A search on Pinside brings up these posts and no answers:
https://pinside.com/pinball/forum/topic/data-east-power-supply-cn5-pin-4-low-voltage
https://pinside.com/pinball/forum/topic/super-hot-capacitor-after-5-secs-of-power-on
I could probably find more if I did some more creative searching.
I'd like to be able to investigate this myself, but I don't have a suspect power supply on hand and I don't have access to a small DMD DE game. So I'm asking for others to see if anyone has the answer to this problem that seems somewhat common.