Now you have me confused. If one of the pass transistors was shorted, it would either give you the
full voltage all the time or nothing all the time. It wouldn't change much with load. I would start by
replacing both of the pass transistors.
Your next problem is trying to fix the voltage regulator. If my memory still can recall those power
supplies, there was a chase your a$$$ around regulation circuit in those power supplies. You
could spend a good deal of time going in circles and still not locate the problem. Your efforts would
be better spent once you obtain a diagram of the beast. Then try looking for the problem.
kv6o wrote:Can anyone point me to a schematic for the TPN1154A power supply? I have one here that puts out 15V+ with no load, and drops to 1V with a small load. Unregulated side looks good at 22V+ steady. I pulled the pass transistors (one is shorted, will replace pair) but the problem still exists even with the bad pass transistor removed. The regulation section is zener based, no LM723... thinking of just replacing with a 723! No crowbar either...