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UPS Project (uninterruptible power supply)

Discussion in 'Power Electronics' started by liamstears, Jan 31, 2013.

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  1. liamstears


    Jan 31, 2013
    Will make this as quick as I can

    The UPS is a UPS-1500SD, looks exactly like the Turbo-X UPS-1500SD but its silver and doesn't say Turbo-X (

    Bought UPS - Plugged in working, charging batteries
    Second hand so think batteries are no good
    Took apart - Checked batteries
    Decided to put it back together and leave it charging a couple days see if the batteries can be charged
    Its dead!

    For some reason since putting it back together and cleaning up a couple bad solder joints it no longer seems to run of the mains.

    3 pics below

    I have traced the mains which I know goes through some resistors to lower the voltage before it hits the IC at the top left of the first pic so I know voltage gets up there.

    The mains also goes through the filter stage and goes to the relays. The bottom relay switches the mains to the white connected to the right of the relays which goes to the transformer. This relay doesn't seem to be switching though when I try to turn on the unit so I bypassed the relay. When bypassing you can hear the transformer hum so there's voltage going through that but still the unit fails to turn on. When pressing the power button the front panel light up dimly and you can hear a relay click on and off (I believe its the middle relay). When it was working you held the power button, the screen lit, the relay clicked and then it beeped and it was on with a display on the front panel. Now when you hold the power button the relay clicks and the display light dimly but that's it, not even a beep anymore

    Could this be because the unit relies on batteries to turn on initially? I wouldn't of though so though so what could possibly be wrong? I will try to be as helpful as I can and really would like to get this fixed...

    EDIT: I have also tested all 3 relays with a separate supply and they seem to be functioning normally



    Last edited: Jan 31, 2013
  2. liamstears


    Jan 31, 2013
    Fixed it!! lol

    Turns out it was simply the fact that it needs batteries that are working to function, even from mains, so I simply need to buy a new set of batteries
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