Main board is marked with 2U3K 640-3080_REV04
TL:DR - Does anyone have this board or the schematic and can tell me what SMD transistors should be at D13 and Q2?
Thanks in advance to anyone willing to read through my story. As I'm also trying to determine if this is purely battery related faults, or is a sign of more issues to do with the UPS?
I picked up an old 2U ups in an auction. Since it was second hand then the batteries in it were of course spent, but I plugged in a few pcs without a battery connected just to test the UPS. Alas I found that it would infrequently cut out and turn off the outputs with the log showing input over voltage errors, I read that it uses the battery in cases of over voltage, so thought that might just be a missing battery issue.
After a bit more testing it started reporting an AVR relay weld error.
So I tested the relays on it, without removing them from the board first, because I'm lazy... and an idiot.
And when testing RY3 found it was sticking, I tested it with reversed polarity and got a lovely spark and smell of burning plastic, but it did then start switching properly?!
I turned the board over and saw a telltale bubble on the Q2 transistor and the UPS would no longer turn on the outputs. Of course I couldn't read the markings on it any more because of the damage but decided I had nothing much to loose so forged ahead by salvaging a random transistor from another board and soldering that in place.
The UPS then powered up the outputs, I tested it with a load but didn't want to test it with the PCs just in case it was still cutting out, so could only load it with to 5%. I also upgraded firmware (with the old battery in temporarily) and it stopped reporting over-voltages, but that might just have been a few days of my household voltage not actually going above 260ac as I have nothing else logging it.
I also tried my hand at popping the seal on the sealed batteries that hadn't bulged and putting some distilled water in them. This did seem to get a bit more life out of them and I put them back in the UPS, it was an 8 battery pack but 5 of the cells hadn't budged so I put 4 of them back for half capacity.
That lasted a few days before it reported a faulty battery, which is to be expected, and I mostly just wanted to test that the UPS was working, I knew I'd have to replace the battery if I wanted to use the UPS for something important, so I left it.
But naturally, I had flooded the batteries! But I thought that would be a risk, and its at least a lesson learned.
So about a week or so after that, after I had reconnected a 15% load, it cut off the outputs, reported a battery charger fault and would not turn the outputs back on.
After cleaning up all the sulfur, that luckily hadn't reached the electronics, I found another battery that had bulged and read 7.8v and the other cells read 11.5v, so I gave up on the batteries and recycled them all.
But the UPS still wouldn't turn on the outputs with the battery unplugged and still reported a battery charger error. And upon inspecting the board I found another telltale bubble had appeared on the D13 transistor, the one right next to the one I replaced (I believe it was marked as a 1P transistor, but I'm not sure).
But since this UPS isn't currently essential in my setup, I thought it best I at least try and find out what transistors are supposed to be there this time.
And try to determine if there's more at fault here than just the battery (and me
)
Because I'm guessing that all of these issues could just be battery related (aside from me melting a transistor obviously) but I have no other battery to test the UPS and a replacement battery would be £140 which I obviously wouldn't want to spend if it turns out something else is wrong with the UPS.
So for anyone who made it this far, I'd appreciated any advice you can give.
Thanks, Pete.