Electronics AC Voltage Stabilizer Repaired
I received this SUN Electronic AC voltage stabilizer with no sign of life.
I opened the machine and start to test semiconductors first :
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.
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.
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)
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?!
This article was prepared for you by Mr Beh from Iran.
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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
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
regards
beh
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
regards
beh
beh
January 12, 2019 at 1:25 pm
Albert
please tell me more about that opamps tester. that you have made.
beh
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.
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.
thanks
beh
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
regards
beh
Andre Gopee
January 14, 2019 at 9:09 pm
Thank you for this great article.
Humberto
January 15, 2019 at 3:44 am
Thanks for sharing this repair. Another device saved from the dump.
beh
January 15, 2019 at 12:05 pm
Hi Humberto
You are welcome. yes the cost of this repair was 1 USD.
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!
beh
January 24, 2019 at 7:12 pm
YOU ARE MOST WELCOME.
Zed
January 26, 2019 at 11:03 am
good job thanks for sharing
BEH
January 27, 2019 at 1:00 pm
Hi Zed
How is going ? and you are welcome.
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?
beh
January 28, 2019 at 6:30 pm
Where is the location of this cap on the board ?