EEVblog Electronics Community Forum
General => General Technical Chat => Topic started by: larrybl on April 20, 2021, 02:17:16 am
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I was given a 1440W Triplight UPS. Battery was dead so I ordered a new one and installed. Everything was working fine, then we had some T-Storms coming in so I put my computer on it and was good for about 6 hours then it just shut off (Main power never went off). I put the computer back on the power strip, and moved the UPS to the bench. I ran it with no-load and it shut off after about 16 hours. I then plugged a shop light in and the UPS shut off again after about 16 hours. I performed the self tests described in the manual and it performed as described.
I am not against tearing into this as I only have $19.99 tied up with the new battery. Inverter works, Switching from mains to battery and back again works. I am guessing an issue with the power on circuit. Could not find a diagram, so this could prove to be difficult with my skill level.
Suggestions?
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You mean it's shutting off while it's still plugged into the wall? Usually the only thing wrong with old UPS's is the batteries go dead, but even with a dead battery they should keep supplying the load while plugged in. I would check the electrolytic capacitors, especially if it has any of the surface mount type, those are notorious for failing. You might have a bad capacitor in the power supply that powers the logic.
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Yes, it just shuts off while plugged in. I powered it back up yesterday, and this morning it is still working. Seems the up-time is getting longer after each un-intended shut down.
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Cold solder joints would be worth looking at too.
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Yes, it just shuts off while plugged in. I powered it back up yesterday, and this morning it is still working. Seems the up-time is getting longer after each un-intended shut down.
Ohhh, that sounds like a symptom of deteriorated electrolytic caps!
Jon
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Yea, It's still on after the power on yesterday, almost 24 hours this time. If it goes off again I may open it up and see if any are bulging or leaking.
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That certainly suggests that they are in bad shape. IMHO it is prudent to replace them now if in doubt, a UPS is absolutely useless if it results in cutting power to the protected equipment during a time that the incoming power is not interrupted, rather than maintaining power to the equipment during an outage. They may temporarily recover to some degree but that is not a fix, they will fail sooner or later.
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I can't confirm, but I think this is a 2011 model. Still working, The top of the case is warm, not hot.
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It died again after estimated 30 hours. I could use one of the old school 110V electric clocks that stops when the power goes off to get an accurate run time.
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Or you could just fix it, because it's obviously broken and will never be trustworthy until you determine the cause of the problem and correct it.
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I'll open it up tomorrow, but 99% sure I won't find the problem.
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Just replace the small electrolytic capcitors, there's probably a switchmode power supply IC and there will be some capacitors associated with that. You can also look around for cracked solder joints, particularly on the relays.
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Not seeing anything out of sorts. I can buy a new 400va ups for less than $50.00 US, which most likely would be less than trying to locate the issue and fix this.
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I see several capacitors that I would suspect, but a visual inspection is completely useless in most cases, they have to get *really* bad before showing any visible signs of problems. You need a ESR meter or a can of freeze spray/air duster can be useful. If you don't feel like trying to troubleshoot it though just replace it, they are cheap and easy to find.