APC Back-UPS XS 1200 Always on Battery - Page 1
Forum section: electronics / repair

author: fuzzoli
author_rank: Regular Contributor
timestamp: April 02, 2019, 12:02:38 am
content: Hi EEVblog people!I have a dead Back-UPS XS 1200 for which the "On Battery" light is always on. From what I can gather from googling, this is a symptom of a bad MOSFET. The only problem is, in the few posts mentioning the MOSFETs, nowhere do they indicatewhichMOSFET(s) are bad. Since the UPS seems to work while "on battery", I assume the bad MOSFET is within the AC sense circuitry (I can't find any schematics).Any thoughts?Thanks,-FrankHolland, PA USA

author: PaulAm
author_rank: Frequent Contributor
timestamp: April 02, 2019, 12:56:27 am
content: Try to find a schematic for that, most of them are floating around. If you can't find the exact model look for something close.I had a 350 that only ran on battery. The charger switching IC had blown itself up. Putting in a new IC and a couple of related caps brought it back to life.Open it up and look for obvious failures. Given the power these things handle many failures are fairly obvious.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: April 02, 2019, 02:26:55 pm
content: If anyone finds a stash of APC, or Tripp Lite schematics... now THAT would be a find.

author: PKTKS
author_rank: Super Contributor
timestamp: April 02, 2019, 03:42:45 pm
content: TRY HERE anything closehttps://www.electronica-pt.com/esquema/conversores-no-break-ups-lcd-inverters/PAUL

author: ChuckDarwin
author_rank: Regular Contributor
timestamp: April 02, 2019, 08:12:52 pm
content: Had several BX/RS? series. Before pulling the soldering iron out, see if this is applicable: Try resetting the line sensitivity to low manually, then adjust if needed. Unplug, re-plug, hold the power button in for 10-12 seconds till all the LEDs go active then tap the power button to set the sensitivity to low. You can toggle through low/med/high and see 1, 2 or 3 LEDs light on the front of the unit. Check the sequence in the docs if you have them, but I think that is correct. I had several units that would randomly set the line sensitivity to high which drove them to battery on power-up (power->relay click->battery) and this was the standard fix with no management software involved.This was the fix I came across for my last unit, now scrapped and glad of it:Cap C41 and four of its friends for good measure.https://www.tomshardware.com/reviews/apc-bx1000-ups-backup-psu-tear-down,4766.html

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: April 02, 2019, 08:21:46 pm
content: Yep, that little collection of schematics is the motherlode, and the full extent of what you will find.APC and Tripp Lite have it locked down really well.

author: PKTKS
author_rank: Super Contributor
timestamp: April 03, 2019, 11:59:55 am
content: Quote from: SoundTech-LG on April 02, 2019, 08:21:46 pmthere is a bit more here...https://elektrotanya.com/?q=keresand btw.. having no schematics is the certain method to haveunserviceable devices...In due time bricks are just discarded.usually replaced with some good serviceable unit.and even WITH SCHEMAS - having no parts (or EXOTIC parts)eventually lead to the same bricks...2 cents of experience on that problemhundreds of schemas collected even though ensures nothingPaul