So on the rare occasion I still bring out my DIY digi modded UA5, reliable, decent sound and pretty fool proof. Last saturday @ bloodkin about 1hr into the first set mine just shut off. Tried a different battery and also tried Lee's battery/cable and nothing would make it turn on. Got home and the same symptoms.
Last night i finally got around to looking into the problem. Opened it up because i though there might be a fuse of some sort in there, nope. No burnt smell either. I then started fiddeling around w/ the multi meter and determined that jack was functional and sending power to the initial contact on the board, but there was no juice @ the power switch. Then Determined that there was +V @ the switch but no ground. Tracing back to the power plug there are a couple of minature resistors which were ok. Then there is this thing.
(circled red)
It appears to be 2 copper wires, 1grnd 1 hot, and they are going through a ring. I am assuming this is some sort of noise shield since the unit is designed to run off a wallwart via AC. Well the ground wire was no longer completing the circuit. So on the underside of the board i tacked a piece of paperclip between the existing enpoints of the broken wire. Magically started working again. So i packed it up and went to a show w/o any real testing except it turned on and it worked fine for a good 2 set Topaz show.
So if any of ya'll have a UA5 that will no longer turn on and doesn't smell toasty inside, this may be the solution to get it up and running again.