UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Television and Video

Notices

Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

Reply
 
Thread Tools
Old 13th Jun 2021, 10:29 pm   #1
Henenen
Tetrode
 
Join Date: Mar 2011
Location: London, UK.
Posts: 67
Default Sony TV with distorted picture

What would cause the picture in a Trinitron to squeeze up, leaving an inch of black at the bottom of the screen?
Henenen is offline   Reply With Quote
Old 14th Jun 2021, 7:16 am   #2
Nickthedentist
Dekatron
 
Nickthedentist's Avatar
 
Join Date: Jan 2005
Location: Oxford, UK.
Posts: 15,639
Default Re: Sony TV with distorted picture

Known as "frame cramp" I think.

One cause can be dried-up electrolytic capacitors in the frame output stage and/or the power supply, so check the supply voltage to the frame output stage.

Note that "Trinitron" can refer to thousands of models from the late 1960s to the early C21st, so a model number would be handy
Nickthedentist is offline   Reply With Quote
Old 14th Jun 2021, 7:41 am   #3
HamishBoxer
Dekatron
 
HamishBoxer's Avatar
 
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,029
Default Re: Sony TV with distorted picture

As stated, dried up caps and depending on the model, dry joints on frame o/put IC.
__________________
G8JET BVWS Member and V.M.A.R.S
HamishBoxer is offline   Reply With Quote
Old 14th Jun 2021, 10:01 am   #4
Welsh Anorak
Dekatron
 
Welsh Anorak's Avatar
 
Join Date: Apr 2005
Location: North Wales, UK.
Posts: 5,479
Default Re: Sony TV with distorted picture

The capacitor responsible is usually right by the frame chip. Large-ish electrolytic. There are only a couple - change both and see to the dry joints and the set will be fine again.
__________________
Glyn
www.gdelectronics.wales
Welsh Anorak is online now   Reply With Quote
Old 14th Jun 2021, 10:18 am   #5
Mooly
Octode
 
Join Date: May 2011
Location: Lancashire, UK.
Posts: 1,017
Default Re: Sony TV with distorted picture

Seem to recall the value was a bit of an oddball one (these days anyway) in many Sony's. Was it 680uF. You could fit a 1000uF but it wasn't quite right linearity wise as I recall.
Mooly is offline   Reply With Quote
Old 14th Jun 2021, 11:06 am   #6
1955APREN
Hexode
 
1955APREN's Avatar
 
Join Date: Nov 2010
Location: Market Drayton, Shropshire, UK.
Posts: 420
Default Re: Sony TV with distorted picture

Boot strap capacitors , used it increase voltage on frame output ic to speed up
fly back time so that next field could start at the right time. There is a diode from the line output transformer that might be o/c and in some sets a resistor
that might be high or o/c.
Regards Derrick
1955APREN is offline   Reply With Quote
Old 14th Jun 2021, 12:01 pm   #7
Welsh Anorak
Dekatron
 
Welsh Anorak's Avatar
 
Join Date: Apr 2005
Location: North Wales, UK.
Posts: 5,479
Default Re: Sony TV with distorted picture

Exactly - usually it's just the capacitor that fails. Usually the compression is noticed before the chip and feed components fail unless you had a very uncritical customer who ended up paying twice as much for the repair!
ISTR 680 or maybe 820uF?
__________________
Glyn
www.gdelectronics.wales
Welsh Anorak is online now   Reply With Quote
Old 14th Jun 2021, 12:32 pm   #8
Mooly
Octode
 
Join Date: May 2011
Location: Lancashire, UK.
Posts: 1,017
Default Re: Sony TV with distorted picture

820uF, could well be Glyn. It must be over 20 years since I last did one.
Mooly is offline   Reply With Quote
Old 14th Jun 2021, 12:54 pm   #9
Henenen
Tetrode
 
Join Date: Mar 2011
Location: London, UK.
Posts: 67
Default Re: Sony TV with distorted picture

Awesome, thanks guys.
Henenen is offline   Reply With Quote
Reply

Thread Tools



All times are GMT. The time now is 4:31 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Copyright ©2002 - 2021, Paul Stenning.