I was running one of my older Ryzen computers and had finished some Windows updates and all of a sudden it shuts down as sparks and a bit of smoke came out of the fairly new (maybe a year old) UPS. I was sitting right there and it really surprised me. I scrambled to unplug the UPS before anything else happened. It also tripped an UPS in the same room that was running another computer at the time.
I swapped the broken UPS for a power strip and that computer booted up just fine. My other computer booted up after I turned its UPS back on. So both computers are fine and it’s only one dead UPS. I pulled the two batteries out and they look ok. I took it partially apart and I cannot yet see what blew. This requires further investigation when I have the time.
That sounds a lot like a lightning surge coming in on your main line. @eebill is the electrician. perhaps he can shed some light on the cause.
I doubt it. Everything else in the house was unaffected and the other computers booted up fine after I pulled this bad UPS out of the power source path. I still need to pull it further apart, but now it's on my workbench. I had it in the garage overnight incase it decided to burn some more - hard to imagine that happening since I removed the batteries.
I hope the two batteries are still good. They are worth at least $50 together and I can use them in other UPS devices I have. Not all my computers have an UPS in the loop.
If it is less than a year old it should still have a Warranty on it.
What is the Make & Model of your UPS?
Sounds like the UPS shorted out or something connected to it shorted it out.
Have you checked to see if you see any bugs that might have shorted out the PCB?
Check inside the burnt outlets to see if you see anything abnormal?
Or simply an electronic part on the PCB shorted out.
By your image I noticed that the burnt area around 3 of the 4 outlets connected to the battery.
A short that big should have immediately tripped the UPS Circuit Breaker.
I wouldn't put those batteries in any other UPS unless you can verify they are good and the cabling connecting the batteries are good and not shorted out.
I have a Cyberpower Pure Sinewave UPS and the batteries lasted almost 8 years before I replaced them for about $35.00 from a 3rd party Manufacturer. It has so far been working fine with the new replacement batteries.
By the way, My PC is on 24/7/365 so the UPS had a load for all those 8 years without any issues.
NOTE: you must have a high quality PSU in your computer that prevented your PC from shorting out also.
See the above pictures. I'm not worried about a warranty claim. I like to find out what happened and I'm not going to pay shipping for such a heavy item. I have replaced many batteries over the years for various models of UPS devices. I prefer APC, but I have two of them that sometimes won't turn on (if they have been off for a month or longer) and I must disconnect a battery - then it works fine. Some kind of lockup problem within the control circuitry I think.
Lol, if the Warranty requires you to pay for shipment it will cost you almost as much as the UPS in material and stamps and very heavy package plus insurance.
Yes it looks like one of the Power transistors blew taking out another in the process:
Now you need to see if the power transistors shorted out due to another electronic component shorting out.
Everything else was working fine and they all are working fine after I swapped out the UPS with a power strip. I think it was an UPS internal failure, but perhaps I should start an FMEA (failure modes and effects analysis)? I was a reliability engineer early on in my career......
Now I feel silly telling you something you probably already know where you are heads over me in Technical knowledge.
But the limited amount of electrical/electronic knowledge I do have plus all the years of troubleshooting helps me diagnose electrical/electronic parts or machinery.
Anyways. what I meant is possibly another electrical or electronic component shorted out inside the PCB itself causing the power transistor to blow.
Though Power transistors can fail for various reasons like Temperature, over voltages, current, opens, vibrations or movements of the unit, age of component, etc.
You can probably replace the Power transistors but if any of the tracings are buried inside the PCB that might be more complicated unless you can bypass by soldering a wire jumping the burnt tracings.
The expense of replacing the damaged MOSFET is minor, but as you say, we don't know what else was damaged in the UPS itself. Given the relatively low cost of the unit (maybe $120 USD), it's not worth my time and safety to repair it. I will keep the batteries as they can be used in other units - batteries are good for about 3 years or so. I will stick with the power strip until I find a good replacement on sale.
Don't feel silly for recommending next steps. Sometimes we question our next steps but to have another person recommend the same thing is reassuring. None of us know everything after all. I have been retired for nine years (as of tomorrow) and I am certainly not aware of the latest techniques in troubleshooting anomalies as are the current reliability engineers. I did spend some time as a component engineer (active devices) on satellite programs before I moved on to safety engineering. Being a systems safety engineer was the peak of my career, as I was able to be in the payload bay of a space shuttle on the launch pad during closeout operations on the payload. That was pretty exciting to me.
I got to the disassembly late this afternoon. I found the source of the problem - I think a power transistor burned, and even cracked the heatsink behind it. The part number (SM6002N) of the similar devices around it indicate that it's an N-Channel Enhancement Mode MOSFET. The application is for power management in inverter systems, so that matches an UPS device.
It looks like those power transistors are in parallel pairs. If there are any unmatched characteristics in the transistors themselves, then sometimes the pair can get unbalanced and one transistor can take too much of the load/current. If you rebuild that, I would at least replace both of the pair (or all 4 on the same heatsink, and maybe even all 8, depending on the circult design). I have seen similar problems with the large audio amplifiers in AVRs.
Good suggestions and I agree with them. However, I won't be rebuilding this UPS. I would always wonder when the next failure would occur, so I will buy an entirely new unit down the road. It was rated at 1500 VA, so it wasn't cheap. I do not trust it for future use though.
I have all APC UPSs myself but they are older units bought used. And yes, I always have to factor the cost of the unit plus a pair of new batteries. I wonder if the quality is dropping on the newer units. Only problem I have right now is my big Smart UPS 1500 says it needs new batteries.
Yes, and new batteries are going to cost you $50 to $70 for a pair, even by using a third party vendor. I recommend Amazon for replacement batteries. Most of my UPS devices are APC. I never had one of those flame out on me.
I tossed out the UPS case and various parts, keeping only the circuit board. I think the unit actually had a 5-year warranty and I think it was bought on Amazon about 3 years ago. Oh well. I like taking stuff apart to see what failed.