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Author Topic: Making a cap kit for a consumer CRT  (Read 542 times)

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Professor Jones

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Making a cap kit for a consumer CRT
« on: December 25, 2018, 10:11:30 am »
Hey,

Merry Christmas to everyone.

I have a consumer CRT (Sony KV-21CL10B) and I would like to change its caps. The picture has some very subtle vertical waves, and no amount of fiddling with the settings would correct that :

https://photos.app.goo.gl/EuG449TyH8ng7Kyq7

That led me to think that the TV might need a new capkit. It's a fairly recent CRT (the previous owner bought it new in 2004) and the caps don't snow any sign of exterior damage, but I know that the TV has been used for thousands of hours. I'm still hesitant on doing this, because it seems like a daunting task.

Anyways, I have the service manual and I've listed all the caps, but since this will be my first time doing this, I have questions :

-The manual indicates several types of caps : ceramic, film, mylar and electric. AFAIK, the only ones I should change are the electric ones, is that right ?
-There are several pcbs/blocks in the TV : RGB amp, processor block, audio block, power supply block, deflection, tuner. Should I change the caps on all of those parts ? I counted 58 electric caps total !

Thanks !

Ken Layton

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Re: Making a cap kit for a consumer CRT
« Reply #1 on: December 25, 2018, 01:05:42 pm »
Only the electrolytic capacitors should be replaced. Get the same UF value. You can go higher in the voltage rating if needed and if it physically fits the board.

I would concentrate on only recapping the following modules (in this order of importance):

1. Power Supply board

2. Deflection section

3. RGB amplifier section

Those are the sections which give the most problems, especially with age & use.

Professor Jones

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Re: Making a cap kit for a consumer CRT
« Reply #2 on: December 26, 2018, 03:06:37 am »
Thanks a lot for your help, I will concentrate on the power and deflection section (turns out there's no cap on the RGB amp). That narrows down the number of caps to change to 29, which is nice ! I'll report back when the work is done.

Zebidee

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Re: Making a cap kit for a consumer CRT
« Reply #3 on: December 27, 2018, 12:37:49 am »
You should seriously consider getting a Bob Parker design ESR meter before charging in to capkit everything. They let you detect bad caps in-circuit 99.9% of the time.

https://www.flippers.com/BlueEsr.html

They are on ebay too. You can buy them as a kit and put it together yourself (easy if you know how to solder, and if you don't...?), or you can buy them pre-built.

That way you will probably find you are only replacing about 4-5 caps instead of 29.

In any case, it is probably worth ordering an electrolytic capacitor "kit" while you are online getting the ESR meter, to give yourself a range of electrolytics (and others if needed) to use.

 
Check out my completed projects!


Professor Jones

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Re: Making a cap kit for a consumer CRT
« Reply #4 on: January 23, 2019, 08:42:29 am »
Well I've replaced nearly all of the most important caps (some caps were missing in the package unfortunately because the store made mistakes...), the image now seems sharper. The little waves are still there, maybe I'm just crazy and it's just how a CRT image is supposed to look...  ???

I noticed a few odd things while replacing the caps :

-some caps were present on the PCB but not listed in the manual
-some caps on the PCB had a different value from the one indicated in the manual (which value should I trust ?)
-on several occasions the traces were lifted off from the board while desoldering (maybe my fault, I don't know why that happened)