Sony Trinitron KVF29SF1 CRT sudden screen smearing

[Stilianos]

I bought this Sony Trinitron from gumtree 3 months ago for retro gaming. It was working perfectly fine until I turned it on yesterday.

Two main problems are:

- When the screen is blue, the on screen display showing the video source looks like it's dissolving. (If you leave it for a while the lettering starts to come back, but I have left it for hours and it has never fully come back)

- The screen smears colors to the right (In general)

Does anyone know why this might happen?

Pictures attached:
https://imgur.com/a/fJhA0Ql

[T3sl4co1l]

Check caps in the video circuit?  Seems like they always used some ~10uF electrolytics there, which shift value/leakage and then the video amps have weird clipping or drool or bias problems.

Probably worth recapping other things too, but don't go crazy right now, just wait until other things start to fail I guess.

Tim

[richnormand]

Dealt with a lot of Trinitron and Sony TVs in the past.

You do not quote a model number, perhaps I have the service manual for it. They are easy to find now.
The fact the "video 1"  also shows the smearing and edges could absolve lots of the upstream baseband circuits.

As mentioned above, electrolytics were a common issue, but also bad solder joints on the video and crt boards. While turned on, a quick test "percussion maintenance" could give a hint.
(A few taps and punches, don't go ape on it....) If these changes the traces it is vibration sensitive. Contacts.

Second point is temperature and contacts. (Be very aware the CRT will retain a HV charge) Remove connectors and reinsert inside.  A dash of contact cleaner may be useful here as you do that. When you get close to the offending board a few spay of "super cold" will be useful.

Other suggestion for Sony's is a small wooden stick to apply pressure and slightly bend the pc boards white the TV is on. This related to bad solder joints and intermittent traces.

Good luck with it.

[Stilianos]

Check caps in the video circuit?  Seems like they always used some ~10uF electrolytics there, which shift value/leakage and then the video amps have weird clipping or drool or bias problems.

Probably worth recapping other things too, but don't go crazy right now, just wait until other things start to fail I guess.

Tim

Dealt with a lot of Trinitron and Sony TVs in the past.

You do not quote a model number, perhaps I have the service manual for it. They are easy to find now.
The fact the "video 1"  also shows the smearing and edges could absolve lots of the upstream baseband circuits.

As mentioned above, electrolytics were a common issue, but also bad solder joints on the video and crt boards. While turned on, a quick test "percussion maintenance" could give a hint.
(A few taps and punches, don't go ape on it....) If these changes the traces it is vibration sensitive. Contacts.

Second point is temperature and contacts. (Be very aware the CRT will retain a HV charge) Remove connectors and reinsert inside.  A dash of contact cleaner may be useful here as you do that. When you get close to the offending board a few spay of "super cold" will be useful.

Other suggestion for Sony's is a small wooden stick to apply pressure and slightly bend the pc boards white the TV is on. This related to bad solder joints and intermittent traces.

Good luck with it.

Cheers guys. If I ever get around to cracking it open I'll let you guys know.

Richnormand the model number is in the title of the thread.

[richnormand]

Sorry. Should not post just before my bedtime...

I looked at my collection and I do not have that exact model.
The schematics and service manuals are available on the web should you ever need them.

[PKTKS]

SONY CRTs  models above 26 (29/32...)  usually are built
around the infamous  MCZ-3001 PSU

A compact w/ ALL builtin regulators.
 (including high power stereo TDA based audio amp)

Check the voltages and the noise on this module
If the PSU needs RECAP is fine easy fix
otherwise (bad fluctuating voltages) google for solutions

This module is common and have a list of tips and solutions

Paul