Sony TV no colour

[TonyS]

Hi, maybe someone has an easy solution to this:

a friend of mine has a Sony KV C2521S that does as follows:

When using the AV composite input it first works fine.

After the set has warmed up, just unplugging and re-connecting the connected DVD
player or switching the set off and on will kill the colour. All is B&W.

The internal tuner will still work in colour.

I don't have any schematics and haven't touched any CRT TVs for a long time.
Could it be that simply tweaking an oscillator could fix the problem?

Thanks

Tony

 

[Jerry G.]

I would be trying another DVD player to see if the DVD player is a
little too far off the colour burst carrier frequency. Both the TV set
and the player have tollerances for stability and accuracy.

If the tuner is working okay, then normally, the baseband input to the
TV set should be working properly. This is unless there is a response
problem in the video input selector circuit or the external video
input preamp section. You will need to use a scope, the service
manual, and a colour standard test generator to properly follow this
up.

I would start by trying another DVD player on the set to make sure
that it is not the DVD player that is slightly off spec.


Jerry G.

 

[TonyS]

I would be trying another DVD player to see if the DVD player is a
little too far off the colour burst carrier frequency. Both the TV set
and the player have tollerances for stability and accuracy.

If the tuner is working okay, then normally, the baseband input to the
TV set should be working properly. This is unless there is a response
problem in the video input selector circuit or the external video
input preamp section. You will need to use a scope, the service
manual, and a colour standard test generator to properly follow this
up.

I would start by trying another DVD player on the set to make sure
that it is not the DVD player that is slightly off spec.


Jerry G.

Thanks Jerry, spot on you are.
It was the DVD player(a Skymaster combination DVD player/set top box, so beware.
eBay again!). I would have thought their crystal generated frequencies would be
more precise.

Tony