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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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13th Jun 2021, 11:29 pm | #1 |
Tetrode
Join Date: Mar 2011
Location: London, UK.
Posts: 81
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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?
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14th Jun 2021, 8:16 am | #2 |
Dekatron
Join Date: Jan 2005
Location: Oxford, UK.
Posts: 17,820
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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 |
14th Jun 2021, 8:41 am | #3 |
Dekatron
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,923
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Re: Sony TV with distorted picture
As stated, dried up caps and depending on the model, dry joints on frame o/put IC.
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G8JET BVWS Archivist and Member V.M.A.R.S |
14th Jun 2021, 11:01 am | #4 |
Dekatron
Join Date: Apr 2005
Location: North Wales, UK.
Posts: 6,884
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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.
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14th Jun 2021, 11:18 am | #5 |
Octode
Join Date: May 2011
Location: Lancashire, UK.
Posts: 1,349
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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.
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14th Jun 2021, 12:06 pm | #6 |
Hexode
Join Date: Nov 2010
Location: Market Drayton, Shropshire, UK.
Posts: 483
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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 |
14th Jun 2021, 1:01 pm | #7 |
Dekatron
Join Date: Apr 2005
Location: North Wales, UK.
Posts: 6,884
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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? |
14th Jun 2021, 1:32 pm | #8 |
Octode
Join Date: May 2011
Location: Lancashire, UK.
Posts: 1,349
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Re: Sony TV with distorted picture
820uF, could well be Glyn. It must be over 20 years since I last did one.
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14th Jun 2021, 1:54 pm | #9 |
Tetrode
Join Date: Mar 2011
Location: London, UK.
Posts: 81
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Re: Sony TV with distorted picture
Awesome, thanks guys.
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