It's an old Sony Trinitron CRT TV, which works fine, but horizontal lines show up once it's turned ON and go away in a few minutes. They don't come back until it's turned off again. Could you please guide me to troubleshoot this issue?

 

I would monitor the DC supply voltages and see if any change significantly as it warms up (careful, there a lethal voltages inside the set ).
If there's a change, it may be do to a leaky electrolytic filter capacitor.

 

Any idea?

 

Any idea?

Other than what I suggested?

 

Maybe read and understand a book about Color TV Servicing.

 

Hello,

As sony uses a trinitron, have a look here:
https://archive.org/details/manualzilla-id-7243870

Bertus

 

Please see the sample video :

Note: all suspected capacitors were checked ( power side, vertical side, around Jungle IC and round H-out) and found OK.

Sample video

 

A moment ago

Looks like horizontal retrace lines.

I would replace all caps in vertical drive area.
Not check, replace with trusted ones

 

View attachment 346756

It's an old Sony Trinitron CRT TV, which works fine, but horizontal lines show up once it's turned ON and go away in a few minutes. They don't come back until it's turned off again. Could you please guide me to troubleshoot this issue?

Based on above.
I would get freeze spray and check by spraying localized components. Warming up seems to correct the issue.

 

A moment ago

Looks like horizontal retrace lines.

I would replace all caps in vertical drive area.
Not check, replace with trusted ones

Actually what I did was : checked with an ESR meter and replaced.

Can't it be a NECK card issue ? or TUNER card issue ? because this TV doesn't have a AV in other than a RF in. So video inputs are directly connect to the RF in

 

Try cold spray on YC jungle.

 

I agree with the freeze spray suggestion. I really don't know how common it is to use the technique today, but it certainly solved a lot of mysteries in the past.

If you don't have freeze spray, an inverted can of. "canned air"—not containing bitterant—will work.

 

Try cold spray on YC jungle.

Thanks for the idea. Assuming that the display becomes OK when the internal components heat up, this can be tried. Since the issue appears when the TV is turned on for the first time, the same thing can be tried by heating the suspected components with a hairdryer.

 

Thanks for the idea. Assuming that the display becomes OK when the internal components heat up, this can be tried. Since the issue appears when the TV is turned on for the first time, the same thing can be tried by heating the suspected components with a hairdryer.

Keep in mind that it takes longer to cool down than heat up, and, heating might reveal faults that aren't present at normal heat levels.