Friday, July 1, 2022

21 Inch CRT Sanyo Television (model CM21YS2S) came in dead now repaired

 I received this television from a customer who wanted it checked.

CRT television are getting phased out here in Kenya very fast but still am getting a few from customers like the one before us.

I asked the customer a brief history of the problem even before opening.

He told me that it started to take time to power up, 1 hour, 2 hours, 3 hours 9 hours, one day and eventually never powered again.

With that I concluded the problem is capacitor related and therefore when I opened it I first did scanning the whole board and noted one capacitor with top part slightly swollen on the vertical circuit.

I replace the capacitor hoping for the best but after powering on I noted the TV was still not powering on but at least this time the red led is on but blinking.

I pulled my ESR meter and started testing all capacitors on the board especially the secondary side and noted most capacitors were faulty, I changed all of them but I could not solve the blinking led.

Since time was not on my side I decided to keep it aside and work on it later.

Later in the evening I decided to continue troubleshooting the board and this time I decided to test capacitors on the power supply section, usually there are few capacitors on this section and therefore I started with the one which filter the startup voltage to the control IC STR W6754.

The first capacitor passed the test with flying colors but was not happy with the second one as you can below.

The capacitor was rated 47uF/35V, here I was expecting ESR reading of less 1 but here I was getting 0.15K , multiply by 1000 you get 150 , This ESR reading can even bring a fighter jet down and therefore the television was justified not to power up.

I changed the capacitor and now it was time to test for any improvements.

After applying the power I noted the red lights was now stable and that put a smile on my face.

I later re-assembled the board back to the tube and everything worked well.

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