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Electronics AC Voltage Stabilizer Repaired

By on January 11, 2019
ac voltage stabilizer repair










I received this SUN Electronic AC voltage stabilizer with no sign of life.

sun electronic ac voltage stabilizer repair

I opened the machine and start to test semiconductors first :

sun electronic ac voltage stabilizer fix

I checked transistor AO1015 it was good. For Testing the IC LM324N I decided to replace it by a good and trusted one for testing this op-amp IC require assembling a circuit on bread board and it is time consuming. I had one unused ic in stock I replaced this IC but no progress!?

Then I start to check three electrolytic capacitors by ESR meter. The ESRs were too high then I replaced them.

sun electronic ac voltage stabilizer fix and repair

Now! Red led start to glow that indicated the voltages are reaching to machine, after 2-3 minutes the green LED turned on. The stable voltages must reach to outlet sockets for use.

sun electronic ac voltage stabilizer fix and repairing

But surprisingly no output! No voltages on outlet sockets! Machine started to work but no output there? But what else is going inside the circuit from big switch two AC line come inside the circuit one directly is connected to one of the switch poles of relay another one goes to the circuit via big polyester capacitor 650 volt 63 nano farad. 12 volt relay is installed in this machine. When the comparator IC LM324N approved the incoming AC voltages is with in tolerance give this answer by sending the 12 volt dc to another switch pols of relay. Relay lets the other line of entrance AC connect with the outlet socket wire and AC output will be ready to use. This relay when 12 VOLT DC is reaching the poles (A.B) must act as switch and poles (C.D)

ac voltage stabilizer circuit board repair

Must be contacted and voltages must be appear in the output socket. I assumed that this relay must be defected component G5LA-14. I pulled this relay out of the circuit and test it. But astonishingly relay passed both testing methods outside the circuit and showed that it is working good! But inside the circuit failed to do the job.

I decided to replace the relay with a fresh one despite of this fact that relay is passed the tests and to see what will happen? And I did this and the machine start to work again and stable voltages reached to outlets! But still this is a question? Why this relay inside the circuit did not work but passed all the tests good outside the circuit?!

ac voltage stabilizer circuit board fix

This article was prepared for you by Mr Beh from Iran.

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  1. Williams D. Umaru

    January 11, 2019 at 1:25 pm

    very interesting and knowledgeable thanks

    • beh

      January 12, 2019 at 12:51 pm

      Millions of this kind of circuits are under service in the world .since it is cheap no one repair it i hope to open a way to repair these machines rather than to dump it . thanks for your comment. beh

  2. Ahmad eissa

    January 11, 2019 at 3:24 pm

    Thank you very much

    • beh

      January 12, 2019 at 12:55 pm

      inside the circuit i also find 4 diodes with code 4001 they were installed as power supply of the machine all of them were good. thank you so much of your comment

  3. Albert van Bemmelen

    January 11, 2019 at 3:54 pm

    The LM324 exists out of 4 Opamps internally if I am not mistaken. I have made a nice and perfect working Opamp tester for this and other single, double and quatro Opamps. It is an easy circuit to build and works always!
    These Relays problems also exist in Washing Mashines and Tumble Dryers were Relays fail to work and need to be replaced. Strange thing is though that the ordered relais sold on Aliexpress were already used and new ones were not available at the time. The fact that they only seem to work is easy established when they in home appliances only start to work after they are ticked on with a screw driver. The Relay switch contacts probably will have burnt out contacts internally. And they fail depending on the current that they switch through. Replacing the Relay is always the best option.

    • beh

      January 12, 2019 at 1:00 pm

      Dear Albert
      thank you so much of your supporting my article .
      but i forgot to tell that i also found a zener diode 4.7 volt inside the circuit regulating of voltages is the job of this zener diode i found it good

    • beh

      January 12, 2019 at 1:25 pm

      please tell me more about that opamps tester. that you have made.

      • Albert van Bemmelen

        January 13, 2019 at 5:51 am

        The circuit is in the mail Beh. (;) It works perfect in case you didn't have one yet! (I have also a couple of tester more that also can test Opamps besides other components).

        • BEH

          January 13, 2019 at 12:13 pm

          thanks ALBERT.

  4. Waleed Rishmawi

    January 11, 2019 at 9:48 pm

    Relays do that very often. Contact not clean enough to pass current. I have seen it happen very often. best thing to do is replace and move on, they are very cheap to replace. thank for sharing and congrats on the repair job.

    • beh

      January 12, 2019 at 1:17 pm

      Hi Waleed
      I always learnt from your articles.

  5. Robert Calk Jr.

    January 12, 2019 at 3:46 am

    Good job, Beh. Sometimes components check fine offboard but then fail when put under a load.

    • beh

      January 12, 2019 at 1:21 pm

      Yes. this is difficult part of job when all meters approve the function of a component but actually is not working.
      thanks Robert for supporting the article

  6. Andre Gopee

    January 14, 2019 at 9:09 pm

    Thank you for this great article.

  7. Humberto

    January 15, 2019 at 3:44 am

    Thanks for sharing this repair. Another device saved from the dump.

  8. beh

    January 15, 2019 at 12:05 pm

    Hi Humberto
    You are welcome. yes the cost of this repair was 1 USD.

  9. Parasuraman S

    January 16, 2019 at 5:05 pm

    Sorry for my belated response! Usually I respond as soon as Jestine Yong's newsletter arrives. But nowadays, I am unable to do so, using my mobile phone, as neither the 'like' nor the comment posted get recorded from the phone. Now I am doing this from my PC.

    Another excellent service with a lot of tips shared!

  10. beh

    January 24, 2019 at 7:12 pm


  11. Zed

    January 26, 2019 at 11:03 am

    good job thanks for sharing

  12. BEH

    January 27, 2019 at 1:00 pm

    Hi Zed
    How is going ? and you are welcome.

  13. Grafton

    January 28, 2019 at 3:23 am

    Hello. I have samsung rear projection tv model number sp-54t8hc it's burning capacitor. Is it high voltage? What must I do?

  14. beh

    January 28, 2019 at 6:30 pm

    Where is the location of this cap on the board ?


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