Numeric UPS problem

Discussion in 'General Electronics Chat' started by eprasadg, Oct 9, 2014.

  1. eprasadg

    Thread Starter New Member

    Jul 28, 2012
    10
    0
    I have, in fact i had Numeric 600VA digital Ex ups. It was working fine.
    Recently the UPS output goes off moment the mains fail.
    Battery is relatively new and good (checked)

    Can anybody here help me on this problem. If anyone is having the circuit diagram please forward it to me.

    Thanks in advance
     
  2. MrAl

    Well-Known Member

    Jun 17, 2014
    2,429
    490
    Hi,

    Wow, that's exactly the opposite of what you want it to do :)

    I see you did not post that long ago so perhaps someone has some more information, but just in case they dont a last resort may be to trace out the circuit and try to figure out what parts are being used, and if you can draw a schematic from that maybe someone would be able to help after reading the schematic. It is a lot of work but sometimes that's the only way. Hopefully someone has one already though.

    You might also need some test equipment, and i am not sure what you have on hand or can get. You also have to be very careful with this kind of circuit as there are parts inside that will have somewhat higher voltages.
     
  3. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    you might check the battery voltage, a few ups's will not even charge the battery if the battery isnt above a certain level, so replacing a battery and ups not working is pretty common. might have to charge the battery with an external charger.
     
  4. eprasadg

    Thread Starter New Member

    Jul 28, 2012
    10
    0
    thanks for reply.
    i have checked the battery with some other ups (of my friend)
     
  5. eprasadg

    Thread Starter New Member

    Jul 28, 2012
    10
    0
    yes, that is option. But their r many ifs, and buts' (doubt and uncertainties)in it.
    i have Digital multimeter, soldering irn etc with me.
     
  6. MrAl

    Well-Known Member

    Jun 17, 2014
    2,429
    490
    Hi again,

    What makes it hard is sometimes you can not run the equipment up to test it either because it shuts down automatically. In these cases you really have to know what is in the circuit so you can bypass that and run it up little by little and see what is happening. Without a schematic i dont know if this is possible unless you can spot some bad components, like burnt parts.
    I got lucky with a TV set recently where i found some bad electrolytic caps. You can tell they are bad because the tops bulge and sometimes a liquid comes out from the bottom. Once you see this, you can remove the cap and replace it with a new one and see if it works after that.
    Electrolytic cap failures are common so you can look for this too. It could be as simple as a bad cap. Look for bulging tops or anything that looks like it could have leaked out of the cap top or bottom. You have to look close to see the bottom leakage though because sometimes the parts are mounted very close together.
     
  7. eetech00

    Active Member

    Jun 8, 2013
    649
    112
    Hi

    I could find any manual on your UPS.

    Some UPS's have a "Bypass" mode. This mode allows a hot swap of batteries (or other). It basically bypasses the internal UPS supply and connects the load to the house AC. Did you check if maybe its in Bypass mode?

    eT
     
  8. eprasadg

    Thread Starter New Member

    Jul 28, 2012
    10
    0
    UPS Given to service center guy, he replaced the entire card and charged me INR 350/-. Backup time not checked yet. thanks u all for replies.
     
  9. AnalogKid

    Distinguished Member

    Aug 1, 2013
    4,532
    1,251
    I'm not familiar with that specific model, but in general... A common topology for a UPS is to pass the input powerline straight through to the output connectors through a relay. When power fails, the relay goes click and switches the output connectors away from, the input, over to the output of the battery=powered DC/AC inverter circuit. If that is how your UPS is supposed to work then a) the inverter circuit/power output stage is not functioning; or b) the changeover relay isn't changing over.

    ak
     
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