Repairing APC Backup UPS 700
After several years my APC Backup UPS 700 broke down. First it started with some rattling noise during power on, but later it wouldn't power on anymore. When I tried to power it on, by holding the power button pressed, it sounded like a clicking pinball machine. Since the battery was already replaced a little while ago, there was probably more going on.
I found out the these issue's where caused by bad capacitors. Replacing these isn't difficult to do. Also I would recommend to replace all the capacitors on the PCB instead of only replacing the faulty one(s).
Opening up the APC Backup UPS and inside
Opening the UPS is easy, just remove all the screws, than you can open up the housing. Behind the battery cover there are 2 screws also. Please take note of how all the cables are routed inside and when you put it back together use the same routing. This is important because there are heat sinks on the PCB that can run hot and you don't want it to melt down the wires.
APC Backup UPS PCB top and bottom side
On the PCB there are 11 capacitors which must be replaced. Take care when desoldering these since the bottom side of the PCB has SMT components on it. Also check for bottom side of the PCB for bad solder joints.
APC Backup UPS bad capacitors
During replacement I found 2 capacitors which measured only 8uF instead of 22uF.
Testing the APC Backup UPS
The APC Backup UPS 700 has an USB interface, through that you can read out parameters like: current load, line voltage, remaining battery time, temperature and much more. From the APC website you can download a utility to run a (quick) self-check. When it has passed I would test it with a load in order to see if it stays okay when it runs on the battery.
My APC Backup UPS 700 passed all the tests and is back in working order again.
