Comment on UPS problem... Again

• BigDanishGuy@sh.itjust.works ⁨3⁩ ⁨days⁩ ago

  1. Almost there is definitely a problem. It was working fine, but sometimes it would just not go to batteries and stuck in a fault with continuous beep. After that, I let it for 2 weeks, the batteries were 5V, but I tried to charge them and for now they went to 12.6V stable (as normal…), but even with that it does the problem described and does not works as before

  That does sound like some part of the controller electronics has been dieing for a while, and has now finally keeled over.

  3. I’ve tested the resistors, all proper to their written value, and relays, proper resistance too (85 ohms for one (just on the brown power plant cable), and 260 for the others)

  You wrote originally, that you tested what you could with desoldering anything. Measuring resistance in circuit always renders a murky result.

  The brown wire is likely what is known as phase or live. Blue will be neutral. But measuring resistance on the input only tells you how much current will flow in the present state of relays.

  What could help you come closer to an answer is following the first law of troubleshooting “thou shalt check voltages”. With a device that operates two live rails this will not be both easy and safe at the same time, so don’t rush it. I suggest you figure out what voltages to measure, then solder wires to the relevant nodes. Terminate the wires in a terminal block, where you’re protected from touching the screw. Assemble the device as best you can with all the wires coming out, and then power it on, get your voltages and deduce from that.

  Whatever you do, do not poke about a live UPS circuit with your multimeter probes directly.

  My initial working theory would be that the transistor switching the fan is dead and I would be looking closely in that area. If that transistor has failed closed and is shorting the controller electronics VCC rail, that would explain a lot. Maybe I’d go so far as to test it without checking voltages (gasp!)

  Will try to find others batteries to try, but normally it charges batteries by lighting up the display properly + the fan does not start. And here the UPS is not connect to any AC power, only the batteries were plugged

  If 12.6V is normal for your batteries, then there’s no reason to troubleshoot that route any further. 12.6 is little low for lead acid, but if it’s a different chemistry. Anyway keeping extra batteries is always a good idea.

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  • foremanguy92_@lemmy.ml ⁨3⁩ ⁨days⁩ ago

    That does sound like some part of the controller electronics has been dieing for a while, and has now finally keeled over.

    Will try to check the transistor and else

    You wrote originally, that you tested what you could with desoldering anything. Measuring resistance in circuit always renders a murky result.

    Okay didn’t really known that, not so good in electricity sadly… :(

    The brown wire is likely what is known as phase or live. Blue will be neutral. But measuring resistance on the input only tells you how much current will flow in the present state of relays. What could help you come closer to an answer is following the first law of troubleshooting “thou shalt check voltages”. With a device that operates two live rails this will not be both easy and safe at the same time, so don’t rush it. I suggest you figure out what voltages to measure, then solder wires to the relevant nodes. Terminate the wires in a terminal block, where you’re protected from touching the screw. Assemble the device as best you can with all the wires coming out, and then power it on, get your voltages and deduce from that.

    Didn’t really understand, can you explain it a bit more? Sorry 😅 About your warning is it dangerous to measure a 230V current with my multimeter (with precautions, gloves mainly)

    My initial working theory would be that the transistor switching the fan is dead and I would be looking closely in that area. If that transistor has failed closed and is shorting the controller electronics VCC rail, that would explain a lot. Maybe I’d go so far as to test it without checking voltages (gasp!)

    Going to check that, but what are the VCC rails?

    About the batteries, I didn’t think they are fully charged with their 12.6V, and I should try to make them go around 12.8-12.9V, but is it possible that because they have gone to 5V they wouldn’t have enough “punch” now and wouldn’t be able to work properly?

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    • BigDanishGuy@sh.itjust.works ⁨3⁩ ⁨days⁩ ago

      Didn’t really understand, can you explain it a bit more? Sorry 😅 About your warning is it dangerous to measure a 230V current with my multimeter (with precautions, gloves mainly)

      Depending on the meter and your approach it can be either safe or lethal. The more I think about it, the more I’d recommend that you just don’t do it at all. Working on 240V installations under voltage, that is something we teach electricians to do safely. Besides the training it involves some special and rather pricey equipment.

      I cannot stress this enough, if you mess up, you will hurt yourself with enough severity that the can easily be fatal. If you don’t know what you’re doing, messing up will be exponentially more likely.

      Desolder the transistor, does the rest of the board light up? If so replace the transistor. Otherwise, get trained assistance on person or replace the UPS. I’m all for learning electronics, but not on a live UPS.

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      • foremanguy92_@lemmy.ml ⁨3⁩ ⁨days⁩ ago

        Thx for the advice, gonna check the transistor

        And I think that my meter is capable of 240V but gonna inspect it with help of electricity guy

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