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APC SU2200NET UPS Battery Backup repair

Discussion in 'Troubleshooting and Repair' started by Korishan, Sep 2, 2015.

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  1. Korishan


    Sep 2, 2015
    Hello everyone.

    I recently purchased the above UPS. I was able to get it to turn on, and test battery switching capability. It does work.

    However, I decided to go ahead and take it apart and inspect my cheap investment (got it for $68 w/ free shipping). It is immaculately clean. Looking deeper on the main board, I noticed two darkened areas on the bottom of the pcb. I flipped it over to inspect and found 2 resisters were discolored.

    Here's the link to my pics I've taken:
    The two resisters are circled in yellow

    The two resisters are the same color banding (though, it was very hard to make out the 3rd stripe) Brown Black Red Gold. I believe that makes these a 1k Ohms 5% Carbon Film. What I don't know is, the wattage of them. I did a band lookup on and saw that there were several listings for these with varying wattages.

    what I'm wondering is, are these resisters ok to use without any problems? The unit is old, and this is the only place I noticed any electronic wear/damage. Should I replace them? If so, what would be a recommended wattage rating?

    Thanks for any help,

  2. Arouse1973

    Arouse1973 Adam

    Dec 18, 2013
    They look like 1/4 watt carbon film resistors. If you want to replace them then some metal film resistors are 0.5 watt for the same size. If the unit is working how it should then just leave it alone, it may go on for years. Dont fix what aint broke. You dont want to become what we call a Sunday Mechanic :)
    Martaine2005 likes this.
  3. Korishan


    Sep 2, 2015
    Ok, thanks. I'll leave it in service as it is and see how well it works.

    I don't have enough battery packs to do a load test on it yet. Found out it set up for 48 Volt battery pack.

    Thanks again for your input.

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