Electronics > Repair

Repair Help for APC UPS BR1500G - F06 error (FIXED!!)

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Vovk_Z:
I tend to double RLP thinking, I tottally agree. It seems to me that main signal processing unit is fine but some output circuit is faulty, e.g. a transistor controlling that AVR relay etc. There possibly could be a burned wire too (because of malfunctioned relay etc).
There is a possibility that TS soldered wrong type of relay because they are different. They are not one type but two types I guess (NO and SPDT ?).

fmashockie:
Thanks for the reply Vovk_Z.  The relays I used as replacement are a different make/model than the originals because they were no longer available.  But I matched them exactly to spec.  All 7 of them are form C relays (both original and replacement).  And it was having the same issue before I replacement the relays.  Which is why I replaced them in the first place lol.

fmashockie:
Just a quick update.  I had some time to work on this thing yesterday.  I might have found a suspect transistor involved in the switching of one of the relays.  It is a internally-biased SOT-23 package.  There are several of the same type on the board and it was giving a much lower forwad voltage on diode test than all the others.  Unfortunately, it broke apart as I was trying to remove it with my heat gun (maybe a sign it was in bad condition).  I've ordered some replacements so it will be a bit until I can work on it again.

I also removed both of the current transformers to test them.  Both of them had normal resistivity/continuity readings (~0-1 ohms on primary, ~100 ohms on secondary).  And I HI-POT tested them and each of them passed up to ~500-1000V (didn't want to crank it up too high as they are small little guys).  There's also another large transformer on the board by the inverter which I'm not quite sure what its purpose is.  The pure-sine wave APC UPS I worked on in the past didn't have one of these.  But I removed/tested it anyway and it seems fine as well.

Also tested all electrolytic caps in-circuit again and none of them seem suspect. 

A side note - it is a real pain to work on these UPSs.  They use very large traces/planes due to the large amount of current/power they have to be able to handle (up to 1500VA).  Desoldering/soldering anything on them can be difficult.  Have to employ my heat gun and soldering gun at same time.  A few years ago I grabbed a Quick 861DW after seeing Dave do a teardown on one.  Works really well!

Thanks again for everyone's input!

fmashockie:
Just wanted to give an update regarding this repair.  So my company just got in two brand new UPSs.  They are BR1000MS2 models - APC's pure-sine wave offering at ~$200.00.  It's a bit different than the one I'm trying to fix since the BR1500G is a simulated sine-wave model.  But I decided to open this brand new one up to see if it could help me troubleshoot.  I forced it into AVR mode by powering it from my Sencor PR57 transformer at ~130VAC.  I then probed the secondary side of the large inverter/AVR transformer and found that voltage on outer taps was = 130VAC and the 'center' tap was = 115VAC. 

I realized that this was about the readings I was getting for the BR1500G even when it was not in AVR mode (i.e. >130VAC input voltage).  For example, even when on battery power, the BR1500G would measure >130VAC and ~115VAC on outer and center taps, respectively.  On the BR1000MS2, on battery power the outer and center taps measured ~120VAC and ~110VAC, respectively.

So with that said, I'm beginning to think the issue is not with the any of the relays after all.  But that there is a problem with the charge/inverter circuit.  Also, there's no noise observed in the AC waveform on the output voltage for the BR1500MS2 unlike the BR1500G.  This would also explain why the BR1500G does not trigger the F06 error in buck mode since it is expecting those secondary outer and center tap voltages. 

If it is a problem with the inverter/charge circuit, could anyone explain/speculate what could account for the increased voltage?  As I said, I clearly recall measuring close to ~140VAC and ~115-120VAC on the outer and center taps of the AVR transformer without it being in AVR mode.  It was in battery mode during these measurements yet still providing normal output voltage (~120VAC).  I'd be curious to know anyone's thoughts on how that could happen.

I'm still waiting on replacement components, but will provide an update once I receive them and install.  Here's a link below to a video I did explaining my observations.  Thanks!

RLP:
Interesting. I think there may be some topological difference between the BR1000MS2 and BR1500G, in terms of how the inverter and transformer(s) work. The BR1000MS2 looks to me like a low frequency inverter, where the big 50Hz transformer is part of the inverter and thus has large high-current terminals on the low voltage side coming from the MOSFETs, and various taps on the high voltage side. I can't tell for sure but the BR1500G looks like a high-frequency inverter design: the transformer on the PCB looks like part of a high-frequency DC-DC boost converter used as part of the inverter (it's too big to be part of the battery charger), and so I suspect that the big transformer is probably only used for AVR. I can't see any big high-current connections to that transformer in your videos - for a 1500VA UPS, there should be some large high-current terminals on the transformer if it steps up the battery voltage to mains voltage?

My thinking is, maybe there could be some legitimate topological reason for the difference in voltages while on battery?

Then again if a relay is stuck (due to drive circuitry etc.), that could also cause the voltages to be different - but (maybe) it may not matter or be detected while on battery power.

I'll be interested to hear what you find after replacing parts.

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