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APC SU1400 All lights flashing issue

Posted: Mon Jun 17, 2019 1:25 pm
by exxos
So my APC 1400 would go for a few weeks, then just die with every light on the front flashing. APC's support pages just says "hardware failure" which is of no help. After searching the web for hours, it seems a couple people claim to have suggested its the relays inside going faulty. I came across a video of a guy with a similar PSU and a similar sounding fault (here).

I documented my progress as I went along, as no doubt I will forget what wire goes where all something :lol: anyone else reading this in the future, this isn't a "how-to guide", its just simply documenting it as I am going along as it may help others in the future..of course at the time of typing, I do not know if this will fix the issue until I try it and that is run for a few weeks... It may well just explode after I fiddled with it, who knows...

The very dusty and poorly power supply..
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Removing the bottom screws to release the black case..
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removing the top plastic cover, which just pulled off..
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Annoying metal lug things, I managed to fiddle the board out of these.. There is also a screw on the back of the case which needs to be removed as it holds the circuit board in place..
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..and it would be too easy if the board just lifted out at this point...
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Time to investigate..
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The main one is the huge connector at the end of the transformer cables needs to come out..
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The ribbon cable needs unplugging from the right side of the board, and the battery backup cables need the screw removing to release them...
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Large connector comes out by pushing their tabs inwards and simply lifts out..
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The black cable need some plodding next as this is in the way...
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There is also a cable tie hidden away at the back that needs decapitating.
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This annoying plastic box had to be moved out of the way as there was some plastic bits on the heatsink fins preventing the board from pulling out, so I just unscrew the box, and pushed the clips gently inside, so it will come out, and the ribbon cable comes out with it..
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White connector comes out next...
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a better view of the cable tie (not yet chopped) and black cable removed...
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lot more freedom now, getting there..
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The blue and brown cables come out next....then unscrew the white and black cables on the heatsink..
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These are the relays I'm going to un-solder next and see if I can find some compatible replacements..
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more to come later...

Re: APC SU1400 All lights flashing issue

Posted: Mon Jun 17, 2019 2:08 pm
by exxos
These were a bugger to get out :roll:

4 of the relays are the same, so makes life a little easier.. now to see if they still exist...

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Original datasheets...
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The ones I think I am going to order are... ... dp/2213726 ... dp/1175017

There are so many variations and series of relays its unreal :stars: :stars: But these are same contact ratings, same (ish) coil resistances (I didn't want to use a lower coil resistance as I don't know if the driver transistors could cope (to lazy to check) and didn't want to risk it). Farnell relays may switch a bit quicker.. but overall, they seem like they will do the job and I am sick of looking at relays now anyway :roll:

Re: APC SU1400 All lights flashing issue

Posted: Mon Jun 17, 2019 3:48 pm
by exxos
Hmm that can't be right...

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2 of the relays measured odd..


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That looks pretty toasted to me.

Re: APC SU1400 All lights flashing issue

Posted: Thu Jun 20, 2019 12:57 pm
by exxos
New relays soldered in... next to try and work out how to put this thing back together again...

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Re: APC SU1400 All lights flashing issue

Posted: Thu Jun 20, 2019 1:45 pm
by exxos
OK so back together.. this didn't end well :(

I started with it plugged direct into the mains, and it seemed to turn on do self test fine. So I put it on my variac and turned down the voltage slowly until the under voltage light turned on.. which it did at 199VAC

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So I slowly started turning the voltage up and at around 200V the thing went dead and just the top red light was on... so I turned it off and on again then got the original fault...

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Then there was a loud POP and the magic smoke escaped :roll:

So I will take it to bits and see what blew... but overall it looks like new PSU time :cry:

Re: APC SU1400 All lights flashing issue

Posted: Thu Jun 20, 2019 1:58 pm
by exxos
Looks like the MOV's have blown up. I don't understand why since I was only inputting 220VAC.

Though oddly the overvoltage light didn't come on in all this, just went into "all lights flashing again". I know it was working previously as it was normally on most of the day. So I suspect the "all lights flashing" is when the input voltage goes to high , or out of spec of the PSU and it can't "deal with it" and goes nuts.

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So in conclusion.. While changing the relays may fix some peoples issues, it didn't in this case. I would suggest anyone reading this and having "all lights flashing" not to bother messing with it and buy a new PSU... Which is what I am now going to do :)