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UPS-SL650 Repaired

By on September 1, 2015
ups repair








This UPS-SL650 was brought to me and the complaint was no power.

ups repair1

I found the ON/OFF knob in the front panel was broken.

ups repair2

But fortunately I had a spare from another similar unit, so it was replaced.

ups repair3

Note the number of pins is not equal, therefore the ON/OFF knob had to be replaced from one front panel to the other one.

When the device was tested some troubles appeared, and when I put my magnifying glass to look at the circuit board, see what appeared now:

dry joint

There was a burnt solder joint in the PCB.

ups repair5

As you can see from the above photo, the connector was extracted and it was fully damaged, therefore as I had no spare connector I had an idea: to substitute this pin for a long wire (in case in some other time any tech has to extract this connector the cable is long enough to permit this action) soldered in the same track.

ups repair6

By the way the contacts of the five relays were re-soldered, and the same with some other cold solder joints there were in the circuit. Look at the following photo how was the device before closing it.

ups repair7

I replaced the battery also because it was not in good condition.

ups battery

The UPS was tested and look at the result:

ups repairing

Mission accomplished, another electronic device saved from the dump.



This article was prepared for you by Humberto Rodriguez, one of our ‘Master Authors’ from Cuba.

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Note: You may check his previous repair article in the below link:




  1. Mayank Tyagi

    September 1, 2015 at 10:44 pm

    its very useful and your all article also you are genius sir .
    Thanks a lot sir.

    • Humberto

      September 2, 2015 at 10:54 pm

      Thanks Mayank, I really appreciate your opinion.

  2. Yogesh Panchal

    September 1, 2015 at 11:11 pm

    Nice job Humerto.

    • Humberto

      September 2, 2015 at 10:55 pm

      Thanks Yogesh.

  3. Robert Calk

    September 2, 2015 at 12:41 am

    Good job, Humberto.

    • Humberto

      September 2, 2015 at 11:02 pm

      Thanks robert, you are always welcome.

  4. Mark

    September 2, 2015 at 5:21 am

    Hey Humberto,

    Thanks for your article. I wonder if it was a voltage spike that caused the problem in the first place or just arcing across cold solder joints? It certainly did a bit of damage! Just as you did, sometimes you have to use your imagination in your repairs, especially when the correct parts are not available.

    Well done!

  5. Humberto

    September 2, 2015 at 11:07 pm

    Hi Mark, I can say that this kind of malfunctions are typical in this model of UPS, most of the times when the original baterry die. In my opinion they are poorly made. Thanks for your opinion.

  6. Julio

    August 13, 2017 at 3:36 am

    Hi, I would like to know what the front panel wiring is like with the orange plug. Thank you

    • Jose Rodriguez

      October 31, 2017 at 11:58 pm

      Hi, I'm from Cuba, I have one with that good connector, the LEDs and the ignition button are on the front connector, if you remove the plate and look at it from above, from right to left the pins 1 and 2 are the ignition button; the 3y4 backup led; 5y6 line led; 7y8 fault led. I hope it serves you if you have any questions write me my address is gmail jrodrigueztvs. If you have this type of backup I need you to send me the plans of how the internal cables of this are, or pictures or something that illustrates how the cables go to the board, the transformer and the outlets. Beforehand thank you very much

  7. Jose Rodriguez

    October 30, 2017 at 8:25 pm

    Hi, I'm from Cuba in advance congratulations for your excellent work, I hope everyone did the same. the case is that I recently received a UPS-SL650 UPS but I had all the internal cables cut I saw that on your page have that model and repaired what I wanted is to ask me photos or some plan of how to reconnect everything again. If I could I would buy another one, but that's what there is. I hope you help me and thanks in advance.

  8. Yasmany

    June 7, 2020 at 1:51 am

    le puedo poner una bateria de 20A 12volts

    I can put a battery of 20A 12volts


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