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AC Voltage Protector Repaired Part 2

By on November 18, 2014











In the first part I mentioned that after replacement with the same part number the device would started to work normally again. However after few weeks of testing the device, it started to malfunction again. Please click the below link to read the first part:


The problem was, after plug into the AC wall socket, all the 3 LEDs were lighted up.

ac voltage protector

I opened the device and recheck all the components. I checked all the components one by one again and found the big 220uf 25 volt e-cap capacitance value had dropped to 140uf! When I tested this e-cap with my ESR meter I found that the value was 2.1 Ohm instead of 0.4 ohm. The last time I checked on this e-cap it was good. The function of this e-cap is to remove the ripples after the bridge rectifier. Since this e-cap have problem, the uneven DC was supplied to the DBL324 IC.


Due to this, the IC starts to work in a strange manner causing the 3 LEDs to light up. Other components like the diodes were checked to be good. The 5.6 Volt zener diode (C5V6PH) was checked to be good also with my zener diode tester. The conclusion was an e-cap and IC replacement solved the problem. I managed to run this device for longer time and this time it was running very well.

ac voltage protectors

Note: We as repair tech will do the best we can to solve electronics problem but sometimes you will get repeated call by customers because even though you have tested the repaired equipment for many hours and days, there will be certain percentage the repaired equipment will break down again. Example, you found a secondary diode in power section shorted but after few weeks one of the secondary filter capacitors started to give problem. On the first repair you are very sure that you have tested the secondary filter capacitors and all were found to be good. Although it is rare to see such problem, it does happen.

This article was prepared for you by Mr Beh, one of our ‘Master Authors’ from Iran.


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By the way if you have any good repair article that you want me to publish in this blog please do contact me HERE.




  1. Andre Gopee

    November 18, 2014 at 9:32 pm

    Nice article Beh... You can never be sure when a component will fail. It may test good today and fail tomorrow... Sometime it may make us look bad but that's just the fact. Keep up the good work.

    • beh

      November 19, 2014 at 11:53 am

      HI Andre
      thanks for your confirmations.

  2. Sethu ramachandran

    November 18, 2014 at 9:33 pm

    Mr Beh .. very informative and a nice repair tipp.

    • beh

      November 19, 2014 at 11:55 am

      Sethu : you are welcome.

  3. Yogesh Panchal

    November 18, 2014 at 10:08 pm

    You are right Beh! capacitors are always unpredictable

    • beh

      November 19, 2014 at 11:59 am

      Yogesh: yes this true. and thanks for supports.

  4. Waleed Rishmawi

    November 19, 2014 at 1:53 am

    it can happen to anybody. Just do your best and that all what we can do in the repair business. I had few customers coming back complaining about the same problem and I think that is normal. I always look them in the eye and say, hey, good to see you again.

    • beh

      November 19, 2014 at 12:08 pm

      Hi Waleed
      yes this is worst scenario for a repairer .i replace most of electro caps directly before making more problems, and thanks for supports.

  5. Robert

    November 19, 2014 at 2:30 am

    That is very true, Beh. Thanks for the article.

  6. beh

    November 19, 2014 at 12:17 pm

    Robert: in this repair i used my new ATLAS LCR 45 .as you recommend one time in your article i find this meter great , by just pushing a button gives the value and ESR of the cap plus many more info thanks for supports and your good recommendations .

    • Robert

      November 20, 2014 at 3:57 am

      Hi Beh, yes the LCR 45 is a good meter, but it is not an ESR meter. I love all of my Peak Atlas meters!

      • beh

        November 20, 2014 at 3:33 pm

        HI Robert
        yes you are right . the ATLAS ESR 70 gives both the value and ESR
        of the caps in second.

  7. biruk aweke

    November 19, 2014 at 12:49 pm

    HI MR.BEH Very good thanks for sharing.

    • beh

      November 20, 2014 at 1:17 pm

      you are welcome BIRUK.

  8. Fayaz

    November 19, 2014 at 5:06 pm

    Dear Sir,

    Can you please share the schematics I want to make this myself.

  9. Humberto

    November 19, 2014 at 10:15 pm

    good repair beh. Sometimes the equipment returns to the workshop again due to a new failure.
    Have a good day.

  10. beh

    November 20, 2014 at 1:18 pm

    FAYAZ: sorry i do not have schematic.


    November 13, 2016 at 7:26 pm

    Ihad one of them andI have had similar problem i replacement ic LM324for three times didn’t work . After I studied your article andused DBL324 it is working very nice . Good job. I really enjoyed that article


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