This was originally posted on APC forums on 8/6/2015
My APC Smart UPS 1400 shows no signs of life when I power it, and there is no charging voltage on the battery terminals. I found that the primaries of T1, T2 transformers shown in the picture (between pins 1 and 2, and 3 and 4) are open when measured with DMM. The PCB is labeled 640-0732H REV 8. What are the specs for these transformers and where can I get replacements?
This was originally posted on APC forums on 8/7/2015
APC doesn't make schematics or spare parts available, except via their authorized repair facilities. As you're in the US, that would be CoastTec. As users we may not like that, but APC gets to make the rules.
Sometimes the parts have a standard manufacturer part number on them, sometimes they only have a "house number". Your transformers are in the second category - 430-0029 and 430-0003 are APC house numbers.
If both transformer primaries are indeed open, I'd suspect a problem elsewhere and even if you could get the transformers, the replacements would probably fail. Switch-mode power supplies tend to fail with one part taking out a bunch of other parts at the same time, and a UPS is just a fancy switch-mode supply with a battery.
It also looks like this UPS is 18 or 19 years old, and being some flavor of SU1400 it doesn't have a lot of value. If you're trying to save money, I'd suggest finding the least expensive used model on eBay with a black faceplate (those are newer than the beige faceplate ones), from a seller that offers at least a 2-week warranty. With a used unit, you should check the battery float voltage as well and adjust as needed. I'm not going to post it here in APC's forum, but a search for "APC float calibration" (without the quotes) should get you where you need to go. APC's lower-end units tend to drift out of calibration after a few years (generally to the high side) and start cooking batteries.
If you are tempted to purchase a scrap / non-working UPS of the same model as yours to get a whole board to swap, I would advise against it. Units from that era tend to be calibrated by installing different values of components, not by software, and mix-and-match of boards from different units (even ones with closely-related serial numbers) can cause some really odd problems. You've probably noticed lots of writing with magic marker on the boards and sometimes even on the inside of the case - they are leftovers from the complicated calibration process on these older units.
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