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F3 I have no idea. It was just a thin wire not a glass fuse. it burned open as it should. D3 is to the LEFT of the yellow transformer and to the right of R19. (hard to see) - i will snap a shot of the board with wires connected. J3 and J4 both go to the BULKY transformer.
Finally got back to this UPS board. I tested all the caps with Ohm meter and none are low resistance (no shorts). C37 and D3 have been replaced. They are right next to the small transformer. I tested Ohms on both sides of F3 to grouns and nor shorted there either. XVS1 diode on the right is...
Thanks for the reply. To answer your questions. All the fuses are good except F3 that was blown. The bottom filter cap was toast. I replaced it. I will check the other CAP you circled at the top. (Think I did but I will check again with ESR meter).
Actually relay is good and Buzzer too. I retested before pulling out out of circuit it works. Something else god bad. The transformer LOOKS ok and has continuity as expected (not open at least). I have no idea what the Ohm should be. I also tried powering the battery side with a bench...
OK - update on this one. I used the Tin foil trick to find traces connected to F3. It goes to the buzzer. I then also traced the A/C mains side to the bride recifier D27,D30,D31 and D12. All are good. No voltage here when plugged into the mains. Checked the transformer and looks good. I...
Hi folks, I have an APC UPS that is misbehaving. Symptom: DEAD. F3 is blown and I replaced C37 which is a 10uf 400V cap. It was bulging out the SIDE. never saw that before! I identified these in the attached PIC. Does anyone have a schematic or eve some tips on fixing? There are no other...
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