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APC BACK-UPS 650ES schematic

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tester272001

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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 signs of burned components. The transformer looks like good condition, no overheading or browning laminations from what I see.

- - - Updated - - -

By the way. the other fuses F1,F2,F4 are all good. I do not see where F3 goes besides the transformer (PIN3 of the Connector). I tried to trace it on the PCB and no luck. I wonder if this is a 3 layer board?
 

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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 found D3 SHORTED. I then tested the Relay(since it switches the mains into and out of the circuit). It reads in the 3 MegOhms or better and then I applied 12V from a bench supply and no go. I do believe the relay is essentially OPEN. I will pull that and see if I have a relay to do a basic test. It seems like the relay got stuck on DC (normally closed) and that drained the battery down to nothing. I suspect D3 killed the filter cap 10uf 400V. Not sure what blew F3 still. This is an interesting one.
 

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 supply and is no happier than with a battery. I thnk the sensing circuitry must have gone. I will wait a bit and see if any schematic turns up.
 

Hello tester272001,
Please refer to picture link below:

IdUr80z.jpg

Have you checked the three other fuses marked in the picture?

Also, you need to measure, (with an ohm meter) across the main filter
capacitors for a short.

Please let us know what results you get.
Regards,
Relayer
 

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).
 

Hello tester272001,

I will check the other CAP you circled at the top. (Think I did but I will check again with ESR meter).

I meant for you to place your multi-meter across the capacitor to determine if there is a short across it. It needs to
remain in circuit. Set your meter to a high ohms range.
Measuring the cap won't mean its gone short circuit, as they rarely do. Its more to determine if a short exists in the
rest of the circuitry the cap is filtering. i.e. diodes, MOSFET's etc.
Regards,
Relayer
 

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 OPEN but i suspect that is only for transient suppression. I have not located a schematic yet...:thumbsdown:
 

Hello tester272001,
Can you please refer to the picture below:

P7dIT6O.jpg

(1) What value was F3 as shown with the GREEN box?
I doubt it was a glass type, but if it was, was it blown violently?

(2) In the BLUE rectangle, is that D3, to which you found
was shorted?
Was D3 associated with the coil on the relay?
If not, then there should be a diode that goes across the coil connections. Perhaps on the
underside of the board.

(3) The two boxes marked in RED, are they the connectors
(J3 [I think that its labled that] and J4) that are attached to the transformer?
Would it be possible for you to label the transformer wires to be in conjunction
with the connectors on the PCB which I've already marked?
This will just make it easier to see what is connected to what.

Would it also be possible for you to take a piccie of the solder side of the board as well?

Regards,
Relayer
 

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.
 

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