Autopilot dig-220 advice - suspect bad power supply

strysnie

0
LifeTime Supporter
Mar 14, 2012
5
MAryville, TN
Autopilot dig-220 - about 8 years old
SC-60 cell - about 3.5 years old

Was getting low amps warning and that "bad electrical" smell from the unit as if something is overheating. Disassembled and had several caps blown, tops popped and covers overheated and black/brown. Fans had seized due to corrosion which might have started the failure process. Removed all of the 1000, the 3000, and the 2 10000 microfarad caps and tested, a few had 0 capacitance, a couple had minimal, and a couple were good. Main board was discolored on top left but no signs of burning or broken traces. Tested coil for continuity, all 4 windings had continuity, no shorts between windings. Replaced all of the caps listed above and the fans.

After reassembly initially worked and tested fine. Then when I checked it again later that day had same symptoms as before my "fix" - low amps warning and that "bad electrical" smell from the unit as if something is still overheating. Voltage was low, about 4v, amps varied but were low under 4. Cell had some calcium deposits, cleaned it and the tri-sensor per manual. Now have check cell warning and 0v with amps varied between 4 and 5. Similar results on power levels 1, 2, and 3.

Is there anything else I can test in the power supply or do I just have to give up and buy a new one? I hate doing that because it appears to be a pretty simple design and I suspect it just needs one or more other failed components replaced. But reading here I'm afraid this is the end as apparently no circuit documentation is available.
 
Unfortunately, there's probably more damage to the circuit board than the visible caps. My guess is that if you inspect the board more closely, you're going to find burnt tracers on the pcb... especially on the underside (which I'm assuming you had a chance to inspect while you were resoldering the caps back on).
There may be a chance that it's showing 0 volts if the cell hadn't had a chance to power up before you run the TEST mode. To eliminate this possiblity, press the PUMP button to see if it says REMOTE RUNS PUMP. Also, put the unit in BOOST mode for about 2 minutes before running the TEST mode so the cells have a chance to ramp power up.
 
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