APC Smart-UPS 1000XL repair and mods

[handypaul]

Hi all,
So I finally managed to get hold of an APC Smart-UPS 1000XL from fleabay described as “For parts or not working”. I’ve been after one of these as a replacement for a Smart-UPS 2200 as I wanted the ability to add extra batteries and it will be easier to manage batteries in pairs (rather than sets of 4). And the XL models are designed from the outset to support additional external batteries.

So I stripped it down and gave it a good check over. The only obvious faults were a broken thermostat (AIRPAX 67L110) @ TS1 and a partially broken ferrite (50mm L x 20mm Dia) on the 24V cable. I’m guessing the UPS was dropped at some point. None of the caps appear swollen. I reassembled it and fitted a pair of known good and charged batteries. At power on all the ‘Load’ and ‘Battery charge’ LEDs lit and stayed on which I believe indicates an internal fault.

I’ve now replaced the thermostat at TS1 and the UPS starts up OK but appears to be stuck on battery power. From reading around it seems one or more of the relays might have welded shut. Is it possible to test them in situ?

I’ve already got replacements for the caps at C65, C77, C87 and C102. Is it worth doing the 5x 22uF 16v caps as well?

How much latitude do I have when replacing the broken ferrite in terms of size?

FYI I’ve already found the following threads on here:-
www.eevblog.com/forum/beginners/ups-batteries-questions/msg493177/#msg493177
www.eevblog.com/forum/projects/cool-tutorial-converting-an-apc-ups-into-a-powerful-sinewave-inverter/

And various other articles including this one:-
https://zipstore.ru/blog/tipovaya-neispravnost-ibp-apc-smart-1000-1500-640-7734d/

I’ve already chopped out the battery disconnect plug so that’s removed 800mm of surplus cable. The front panel ribbon and the USB daughterboard ribbon have been replaced with wires and 8 pin connectors (good idea ‘cte7ds’).

When funds permit I plan on upgrading the 10AWG battery wiring to 8AWG. Also to replace the existing 80mm fan with a 92mm version and modify the case to improve airflow.

Anything else I should consider?

I'll post some photos later.

[tkamiya]

I had one of those rack mount APC UPS failed with a bad relay.  It was obvious as outer casing was a clear plastic and I can see previous arching on inner side.  Interestingly enough, when I took it off from PCB and tested it by itself, it worked fine.  Yet, under load and in circuit, it failed.  I took one out of for-parts unit, replaced it, and all was fine.

Apparently, my model which I don't remember if it was 1000VA or 1500VA had a firmware bug that caused relay to chatter.  I am theorizing that may have caused excessive on/off cycle on that relay and caused its contact to arc over.  There is no way to verify this.  Updated the firmware anyway.

[handypaul]

Broken thermostat (now replaced):-

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Can anyone identify this component? Might the brown discolouration on the end face mean anything?

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Made the USB daughterboard detachable with a keyed latching 8 pin connector:-

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I've now replaced all the caps except the big black one by the heatsinks. But its still stuck on battery so I'll probably have to start on the relays.

[tkamiya]

That is a capacitor, X2 grade.  220 nano farad. 

[tkamiya]

If it's stuck on battery mode, I'd guess one possible cause is it doesn't see mains voltage coming in.  Did you check relays?  Did you check fuse?  Did you trace A/C input, rectifier, and whatever follows? 

[handypaul]

So I finally got back to this project (busy at work and TBH a bit disheartened that my repairs apparently hadn't worked).

I ended up buying another UPS (APC Smart-UPS 750XL from fleabay described as “working”) cheap. Partly this was so I'd have a working UPS but also to see what the differences were other than battery size.

So I charged the battery set, hooked it all up and the 750XL displayed the same apparent fault as the 1000XL I was attempting to repair!!!!

They would both power-on, self-test OK but would stay on battery power. So I tested both mains leads that I was using on my workbench and found that the fuses had gone in both of them!!! Duh 

So my replacement of 2 relays was probably unnecessary. Ho-hum. 

Next stage is to check the the battery charge/float voltage on the 1000XL, upgrade the battery cabling and set it up with a couple of larger external batteries.

Before I do that I'll do a separate post showing the few differences between the 750XL and the 1000XL. I don't know enough but from reading around the subject I wonder if there is scope to upgrade the 750XL relatively easily as there seems to be more of them available second-hand.

Cheers,

P