Sony KV20S10 - Pic dies after 1 second

[Flux_Capacitor]

I have been trying to find some knowledgeable people to give me some tips, this forum looks like I have found you.

I have a Sony KV20S10 20 inch Trinitron that I use in my work area and recently it started to act up. I am not overly worried about this unit as it is more of a luxury for me to have in my workshop though I would love to get it back working! Later, I will share another TV issue with a 35 inch Mitsubishi CRT that I have in a finished basement that ALSO went around the same time... now that one I want very much to fix as it was always an awesome TV! Anyway, more on that once I do some more investigating.

When powering up the KV20S10 it shuts down after 1 second of operation ... as soon as the picture comes on. I can feel the static charge when I place my hand in front of the screen.

I have replaced 470uF 16v cap as suggested by a Sony service bulletin describing similar symptoms - though this did not solve the problem. The new cap and the old do measure differently on my ohm meter but I figure it as one being older. I have never really mastered the science of measuring a capacitor. I have a Fluke MM - any Cap testing tricks would be greatly appreciated.

I noticed that if I turn the picture all the way down on the Flyback the unit will power up - though no pic. When I slowly bring the Picture adjustment up - as soon as I get picture the unit shuts down within less than a second.

Any advice on how to proceed in trouble shooting this unit would be greatly appreciated.

I am well aware on how to short the anode - don't worry I will not be electrocuting myself.

I have the service manual for this unit - I would love to upload it as it may help others however it is larger than 2megs. Perhaps a moderator could upload it? If so, I could email to the moderator. The size is about 5mb in PDF form.

Thanks for any advice in this matter.

[japlytic]

Re: Sony KV20S10 - Pic dies after 1 second

What is the control on the flyback you are adjusting for the picture (Screen, Focus, etc.)?
It appears that a protection circuit is shutting down the set when this control is turned up.
A good place to place the service manual is www.eserviceinfo.com (you need to register for free to upload it) - on this site, I have placed a number of circuits for power supplies.

[Flux_Capacitor]

Re: Sony KV20S10 - Pic dies after 1 second

Thanks for the reply.

I meant to say "Screen" when I was referring to picture. So, to answer your question I am adjusting the "Screen" control on the flyback. The TV will stay on when the screen control is set completely off / counter clockwise. When I slowly turn the screen control up I get picture for about less than a second and the unit shuts down. Like you said, it is very likely a protection circuit of some sort. This is driving me nuts because I can't feel for anything heating up and doesn't give me any time to do any other testing.

I am really dumbfounded on this one.

Thanks for sharing the ESI website. I have attempted to upload the service manual but keep getting an error - perhaps they have a size limit as well. I instead placed it on a website .. Click Here (PDF format)

[repairs online]

Re: Sony KV20S10 - Pic dies after 1 second

Hello,

Quote:

SET SHUTS DOWN INTERMITTENTLY
ENTER SERVICE MODE AND SELECT 'SHAP' AND CHANGE DATE FROM 7 TO 5 -IF THIS FAILS,THEN CHANGE IC301 (P/N# 8-752-069-09)

End Quote


Sincerely

[Harvey]

Re: Sony KV20S10 - Pic dies after 1 second

Its tricky to get into service mode if the set shuts down after 1 second........

[Maxxarcade]

Re: Sony KV20S10 - Pic dies after 1 second

Will it stay on if you unplug the neck board from the CRT?

When you get a picture for a second, does it look normal? Sony sets have a few protection circuits that shut the set down for having too much cathode current going to the CRT. Though usually they just plank the picture, not turn the whole set off.