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Old 21st Apr 2024, 6:34 pm   #21
Maarten
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Default Re: Sony Trinitron KV-M2120U wobbly vertical deflection

I'd start with checking (scope needed) all signals around the horizontal sync and output stage. It looks a bit as if not only the vertical deflection is affected.
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Old 21st Apr 2024, 6:45 pm   #22
Retrorepair
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Default Re: Sony Trinitron KV-M2120U wobbly vertical deflection

I agree, I need another scope I think.
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Old 21st Apr 2024, 9:37 pm   #23
Maarten
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Default Re: Sony Trinitron KV-M2120U wobbly vertical deflection

Come to think of it... Could it be one of the harmonic tuning capacitors in the horizontal output stage? I don't have the schematic handy, but if the sandcastle signal is derived somewhere around there, it could cause strange deflection problems.
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Old 21st Apr 2024, 11:51 pm   #24
IKC2E51R8
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Default Re: Sony Trinitron KV-M2120U wobbly vertical deflection

have you tried changing the Vertical size control potentiometer, ive had similar faults caused by a bad potentiometer.
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Old 22nd Apr 2024, 6:40 am   #25
Retrorepair
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Default Re: Sony Trinitron KV-M2120U wobbly vertical deflection

Quote:
Originally Posted by Maarten View Post
Come to think of it... Could it be one of the harmonic tuning capacitors in the horizontal output stage? I don't have the schematic handy, but if the sandcastle signal is derived somewhere around there, it could cause strange deflection problems.
That's worth looking at, thanks!
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Old 22nd Apr 2024, 6:43 am   #26
Retrorepair
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Default Re: Sony Trinitron KV-M2120U wobbly vertical deflection

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Originally Posted by IKC2E51R8 View Post
have you tried changing the Vertical size control potentiometer, ive had similar faults caused by a bad potentiometer.
I haven't, to be honest it seemed like there was no sync at all but by this point worth a shot.

If it helps diagnose, the image got like this over maybe a minute. Started off a bit jumpy then just slowly shrunk and went like this. Still jumpy. Sorry I realise that's a crap description.

Last edited by Retrorepair; 22nd Apr 2024 at 7:11 am.
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Old 22nd Apr 2024, 9:27 pm   #27
Maarten
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Default Re: Sony Trinitron KV-M2120U wobbly vertical deflection

Quote:
Originally Posted by Retrorepair View Post
Quote:
Originally Posted by Maarten View Post
Come to think of it... Could it be one of the harmonic tuning capacitors in the horizontal output stage? I don't have the schematic handy, but if the sandcastle signal is derived somewhere around there, it could cause strange deflection problems.
That's worth looking at, thanks!
Or possibly any part in the vicinity that may be internally arcing or open crcuit.
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