CRT "shaky" picture

[damanloox]

Hi,

I have a CRT (Sony Trinitron). I'm pretty happy with it - has really nice colours, and sharp, stable picture but... only when "warmed up". When I power it on the picture is shaky in horizontal direction (sorry - not sure how to explain it. What I mean is that it looks like all horizontal lines are slightly moving creating that shaky picture). It only happens when it's "cold" ie. for a few minutes after power on. The picture then stabilises and everything is OK. Does that on all inputs btw. My first guess was to try and change the caps but I thought I'll ask first (for a change )
Any idea what may be causing it or where to start looking?

[Roehrenonkel]

Hi damanloox,
 
maybe it's the degauss-coil staying on too long.
Look if the PTC-resistor in line with it is okay.

Good luck

[decoder_82]

Can you post a video that shows the issue ? It would help to further assist. Thanks

[Vovk_Z]

Dryed 50/60 Hz rectifiers large caps could be a reason too. (It's hard to tell without a photo).

[liaifat85]

Please check if there are cold solder joints. If you find any, resolder them.

[tggzzz]

With old equipment you should always start with measuring the PSU voltages and ripple. Only if those are OK is it worth moving on to other possible causes.

Exactly how the picture shakes could give useful information, e.g. vertically, horizontally, brightness, frequency/period, amplitude.

[m k]

Degaussing is a bit violent, it also includes other effects.

My guess is a bad supply voltage for horizontal deflection circuitry.