Electronics > Repair
Repair Help for APC UPS BR1500G - F06 error (FIXED!!)
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fmashockie:
Hi everyone! New to this forum but I've always been a huge fan of the EEVBlog YT channel!  I'm trying to repair an APC UPS BR1500G.  I had it in storage for a few months (with battery installed unfortunately) and took it back out to test and it started triggering a F06 error.  It would start-up fine, go through a self-test (switching to battery power) and then switch back to mains and trigger this error.  According to the manual, F06 = relay welding.  I've tested all the relays out of circuit and none of them have stuck contacts.  But I replaced them all just in case and it did not resolve the issue (couldn't be that easy  |O).

I found that when forcing the unit into Automatic Voltage Regulation (AVR) mode, the unit will not trigger this error.  But only at increased voltage (>130V).  I can simulate a power failure at this voltage and it will switch to battery power without issue.  I can also put a load on it and it will handle it fine.  But as soon as I bring the voltage back down to normal levels, it will trigger this error again! (Quick note - If I attempt to start-up the unit at a lower than normal voltage like <110V, the unit automatically starts in the F06 error - no self test, etc.)

One thing I noticed while the unit was in AVR mode is that there is a significant ripple that appears/disappears at regular intervals on the output.  I observed this while hooking the output up to my oscilloscope.  I have a video of it here () but it is a significant ripple/noise (~10V peaks). 

I would suspect that the transformer is the problem - (maybe the 130V tap has internal breakdown?), but I did a HI-POT test on the transformer up to 1000V and it passed the test.  I've tested similar transformers with internal breakdown and they fail immediately. 

Anyway, I was hoping someone might have some troubleshooting tips/suggestions/help!! This repair is pretty much academic at this point.  It's only a $200 UPS (one of APC's most common offerings).  But I'd love to learn more about how to troubleshoot these things.  Thanks!!
fmashockie:
Is there any additional info I can provide to help better understand the issue? Just lemme know! I would appreciate any help.  Not looking for someone to fix this for me, just how they would approach this problem (at least). 
Vovk_Z:
How old is it? Old ones tend to want to replace small electrolytes which can cause all types of problems. I'm not sure here is such a problem but who knows.
Have you measured output voltage when you regulate input voltage? Is it within range? Does it change as should?
fmashockie:
Thank you for the reply! I did test the electrolytic caps in-circuit with an LCR meter.  For the ones I could measure in-circuit, they measured normal.  But couldn't hurt to measure again and even measure some out of circuit.

The output voltage stays within range when adjusting the input voltage.  For example, in the video I took in my OP, the input voltage is set to ~130VAC.  But output measures ~120VAC. 

What I am trying to figure out is why the unit will only work when voltage is increased and the unit is in buck mode.  If I start it up with mains voltage at normal 120VAC (I am in the US), it will do its self test (switch from mains to battery and back to mains).  Then I hear another relay click, and I see increased noise in the AC waveform, and it triggers this F06 error and shuts down.  If I start the unit with a less than normal voltage, (say 110V), it will automatically go into this F06 error.  The error means relay welding according to the manual, but the relays are fine!
fmashockie:

--- Quote from: Vovk_Z on August 20, 2023, 09:34:47 pm ---How old is it?

Sorry I forgot to answer this question.  It is ~5 years old.  It was in service 24/7 for ~3-4 of those years.  Then I took it out of service and put it into storage.  There was nothing wrong with it when I took it out of service initially.  I did however store it with the battery installed.  The battery appears fine - voltage measurement indicates its in good shape.  The unit can power a load (~100W) on battery power.  It can also run in battery back-up mode just fine as well.


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