UPS shorts out

[tylerlough]

My dad got two free UPS from work, one works fine the other doesn't. It trips its internal breaker as soon as I plug it in. I see nothing wrong with the board, can't find anything wrong. My dad plugged it in with the board disconnected, and it didn't trip. when he plugged the transformer into the board it blows. Not sure if its a problem with the transformer or something on the board. Any help would be great.
Btw the caps are nichicon

[kc8adu]

Re: UPS shorts out

looks like a best power.
look to a welded relay or bad mov's.
those units work well with an external deep cycle battery too.

[tylerlough]

Re: UPS shorts out

how do you test if the mov's are bad, I know they're the red epoxy coated things.
so the relay should be closed not open

[japlytic]

Re: UPS shorts out

Desolder the MOVs and measure the resistance between them. If you get readings near zero ohms, they are shorted and need to be replaced with units of the same type.

[tylerlough]

Re: UPS shorts out

thank you Mr. Ham and Japlytic, because I hate to have to pitch it if its just a bad relay or mov. I did a continuity test and none made it beep, but it might be different with more voltage.

[kc8adu]

Re: UPS shorts out

pull the mov's and try again.
that relay looks odd in the pic.

[arneson]

Re: UPS shorts out

Dust cap on relay can be popped off for closer look.
Board itself looks like it may have been wet?

[tylerlough]

Re: UPS shorts out

I don't think it has ever been wet, and the relay still moves.
Put a piece of paper between the contacts, pugged it in and it didn't blow, so its definitely something on the board and most likly an mov

[tylerlough]

Re: UPS fixed, not really

I fixed it!!! : : :


wasn't worth fixin' because both batteries are bad

[japlytic]

Re: UPS shorts out

Did you try the batteries from the good unit in it first?

If they do work, and the other batteries are bad, you can usually get SLA batteries (typically used in alarm systems) of the same phsical dimensions and voltage for it.

If the unit has two batteries in series, fully charge each 12V battery individually before installing them in the UPS.

[kc8adu]

Re: UPS shorts out

bad batteries not a big deal.
https://www.badcaps.net/forum/showthread.php?t=1579
thats what i do with all the free dead battery ups's i get.
and i never have a problem selling them.

[tylerlough]

Re: UPS shorts out

My Dad checked the batteries, he tried a car battery charger and they still wouldn't come up past 7 volts each. It is still good for parts and stuff
It was refurbished in 03 but the case was made in 94. RIP 06

[Per Hansson]

Re: UPS shorts out

As said earlier, if the battieries are the only problem you can get it up and running for close to nothing...

[willawake]

Re: UPS shorts out

It was refurbished in 03

3 years is about right for replacement of batteries. i guess they changed them then.