Repair instructions for APC Back-UPS RS 500

[Stig Vidar Hovland]

I have two APC Back-UPS RS500 units which failed at charging the battery.
It was a capacitor which failed on both of them and I have also found out
that this failure is rather common for this UPS. Here is my description on
how to repair them. If you have a similar problem that the UPS seems to
work OK with a new and charged battery connected, but fails after a short
time (days) with the 'replace battery' light on, then this could help you.

http://www.heime.org/Lists/Posts/Post.aspx?ID=17

Stig Vidar Hovland

 

[CLARENCE CLAY]

Thanks for the info. This capacitor failed because it was a general purpose
85C part. General purpose capacitors fail due to heat & developed high ESR
in a switching power supply. APC used the wrong capacitor. A 105C capacitors
should be used in the secondary side of a switching power power. They do not
dry out as fast and develop high ESR as soon. A 85c capacitor works well in
the primary 60hz side. If you would to keep your backup working long term
replace the capacitor with a Nichicon low impedance, high reliability 105C
Part. Digi-key part number 493-1811-ND is a Nichicon 22uf 16vdc 105C. Cost
$0.27. Nichicon part number UPW1E220MDD (WWW.DIGIKEY.COM)
Panasonic General Purpose 85C part is $0.15.
APC may know that the part will last a year or they could have made a
mistake but Look at the cost savings of using a 85C part.
I all ways use a 105C capacitor unless it is used on the 60hz side.
I use the Dick Smith ESR Meter designed by Bob Parker to test power
supplies. This meter saved me more than $10,000.00 in time saved since I
built the kit.
THANKS Bob Parker for your outstanding designed ESR meter.
CLARENCE
SOUTHWEST MONITORS&PRINTERS