Compaq T2400H UPS service manual - Page 1
Forum section: electronics / repair

author: IanJ
author_rank: Unknown
timestamp: December 10, 2019, 08:15:16 pm
content: Hi all,Got a dead Compaq T2400H UPS I'd like to get up & running, has anyone got a service manual and/or schematic diagram for it.......or indeed another in a similar series?Thanks,Ian.

author: TheMG
author_rank: Frequent Contributor
timestamp: December 11, 2019, 02:29:00 am
content: First things first... are the batteries in it any good? There are many UPS models that will not power up and act completely dead if the batteries can't at least supply enough power to get the UPS circuitry powered up. This occurs even if the UPS is plugged in to an AC source, it needs power from the batteries to initialize the UPS and energize the relay allowing AC mains to the UPS.

author: IanJ
author_rank: Unknown
timestamp: December 11, 2019, 08:28:05 am
content: Batteries were dead/flat but I had changed them for known good ones.I would reverse engineer the power circuit but theres quite a lot of hardware covering a lot of the main pcb it would be easier with a schematic.Cant see anything on the web........but I live in hope somebody has something.Ian.

author: Electro Detective
author_rank: Super Contributor
timestamp: December 11, 2019, 10:24:47 am
content: What's it doing/not doing?assuming you did pump a healthy 48 volts (52+ in reality) of series battery oomph to get it motivated?

author: TheMG
author_rank: Frequent Contributor
timestamp: December 12, 2019, 01:48:06 am
content: If you've got good battery voltage and the fuses are ok but the unit still acts completely dead (no beeps, clicks, no LEDs), I would suspect maybe a voltage regulator. There should be somewhere on the board a voltage regulator providing power to the main micro-controller. In a UPS that age it would most likely be a linear regulator, probably a 7805 or equivalent. Have a look around the board and measure input and output voltages on any regulator you can find.No need to reverse-engineer the whole circuit at this point. "Thou shall check voltages".Are you able to post a good picture(s) of the circuit board?

author: IanJ
author_rank: Unknown
timestamp: December 12, 2019, 07:10:08 am
content: Hi all,Apologies if I have mis-communicated, and as much as I appreciate the hints n tips, I was really just after the schematic so I can effect a repair on my own YT channel.Theres no other type of video I like better creating than repair videos.Cheers,Ian.

author: TheMG
author_rank: Frequent Contributor
timestamp: December 13, 2019, 01:06:30 am
content: Unfortunately I have nothing to offer in terms of schematics. I know from doing a LOT of research and asking around in the past, with small UPS from various manufacturers, that this documentation is most often not available outside of the manufacturer, unless it happens to have been leaked or reverse engineered, which is rare as there are so many different models out there and most people throw them away rather than seek to have them repaired outside of warranty. Sad, but that's the way more and more things are going these days.

author: Electro Detective
author_rank: Super Contributor
timestamp: December 16, 2019, 01:28:09 am
content: IIRC this model and the APC badged version of it at the time, 'may' have been the same units internallyAPC may have some docs kicking around for theirs,highly doubt you'll find much if anything on the Compaq unit = been there a while backand luckily ?! it was faulty batteries that checked okcoupled with dodgy connections and client's dodgy+ power stripand a blanket of dust and crust.Does the 'patient' resemble the 'borrowed picture' below?Good luck with the videoput me down for a looksee

author: marekm
author_rank: Contributor
timestamp: June 20, 2022, 02:29:36 pm
content: Yes I know it's an old topic. But the only one I found about this type of UPS.I have two such units, and one (after many years of working fine) has just failed. After some time of normal operation, LED 10 blinks red which means "internal UPS overvoltage, contact authorized service".Then it starts working only on battery (not switching to mains, still reporting it on the LED bars) until drained, then restarts (short break seen by connected loads - some reboot, some don't) and works again for some time until this error happens again.It happened a few times in last 24 hours. Any ideas? Which specific APC model is most similar internally so I could look for some schematics?