Sony Trinitron KVF29SF1 CRT sudden screen smearing - Page 1
Forum section: electronics / repair

author: Stilianos
author_rank: Newbie
timestamp: March 17, 2019, 10:13:20 pm
content: 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

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 17, 2019, 10:45:44 pm
content: 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

author: richnormand
author_rank: Unknown
timestamp: March 17, 2019, 11:06:06 pm
content: Dealt with a lot of Trinitron and Sony TVs in the past.You do not quote a model number, perhaps I have the service manual for it.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.

author: Stilianos
author_rank: Newbie
timestamp: March 18, 2019, 08:07:14 am
content: Quote from: T3sl4co1l on March 17, 2019, 10:45:44 pmQuote from: richnormand on March 17, 2019, 11:06:06 pmCheers 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.

author: richnormand
author_rank: Unknown
timestamp: March 18, 2019, 05:05:25 pm
content: 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.

author: PKTKS
author_rank: Super Contributor
timestamp: March 18, 2019, 05:44:58 pm
content: SONY CRTs models above 26 (29/32...) usually are builtaround the infamous MCZ-3001 PSUA compact w/ ALL builtin regulators.(including high power stereo TDA based audio amp)Check the voltages and the noise on this moduleIf the PSU needs RECAP is fine easy fixotherwise (bad fluctuating voltages) google for solutionsThis module is common and have a list of tips and solutionsPaul