Blown High Voltage Capacitor In Power Primary Side
Customer sent to me this Singer DVD system with the complaint of no power symptom. For your information no power symptom can be caused by the power supply board or the mainboard. It is not necessary must be the problem in the power supply section. Unless you have confirmed that the power supply is giving good DC output voltages then you can suspect a bad mainboard. Once the cover was removed, these are the parts that I saw:
Since the complaint was no power obviously the first component that I need to check was the main fuse.
With the use of my Ohmmeter to check on the main fuse, I found it to be open circuit. In the photo below, the arrow is pointing to the main fuse.
For your information there are two separate power supply boards in this DVD system. The one on the table is for , protection, EMI and AC to DC conversion purpose. The one that was hanging (second power supply board) is where the main power supply is. It consisted of power FET, Switch mode transformer, output diodes, filter capacitors, Optoisolator ICs and etc.
When I flipped the second power supply board for visual inspection, I saw a blown high voltage capacitor.
The value was 103 1KV and I replaced it with 103 2KV. Further checking did not found any bad components in the second power supply board.
I concluded that it was only the main fuse and the high voltage capacitor that were bad.
I replaced both components after went through the series light bulb test. The result was good and the DVD player set came back to life again.
Conclusion- Sometimes power supplies repair can be tough but for this repair case, it was quite straight forward without needing any special test equipment to repair it. If you plan to repair switch mode power supplies, you can get Jestine’s SMPS repair ebook here. It is fully recommended and you will find that the information inside the ebook will worth every cents that you have invested. Ok see you in the next repair article…bye!
This article was prepared for you by Suranga Bandara who owns an Electronics repair shop in Anuradapura, Sri Lanka.
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April 17, 2020 at 4:46 pm
A straight forward repair but successful one. Good repair job and keep up the good work. Have a blessed day
Albert van Bemmelen
April 17, 2020 at 5:31 pm
Thanks for sharing! Opening and afterwards closing the case of devices like these must have been the hardest part for most repair engineers. And using a new 2KV HV capacitor probably will prevent it from ever happening again.
April 17, 2020 at 7:55 pm
Sometimes it's good to find a simple repair - it makes up for all those other ones that make you pull your hair out
April 17, 2020 at 10:22 pm
Good job, though straightforward for a professional like you!
April 18, 2020 at 3:07 am
Good work indeed
April 19, 2020 at 8:49 pm
This is not a capacitor , this component i a varactor and its function is to short itself when is over voltage on it. It is for circuit protection . Almost on input wall voltage.
Tnx, Sergio Manor
April 20, 2020 at 3:41 pm
Nice inspection! suranga
April 29, 2020 at 8:42 pm
This component looks like an MOV for surge protection.
October 19, 2020 at 1:39 pm