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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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1st Jan 2022, 5:45 pm | #1 |
Tetrode
Join Date: Feb 2021
Location: Crewe, Cheshire, UK.
Posts: 66
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Strange wide vertical stripe
Any guess what's causing the stripe in the attached photo? I'm using a Hedgehog converter.
Kind regards, Aidan. |
1st Jan 2022, 10:11 pm | #2 |
Heptode
Join Date: Jan 2007
Location: Luton, Bedfordshire, UK.
Posts: 891
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Re: Strange wide vertical stripe
I'm not familiar with this device. Perhaps a humbar of some sort? Maybe try a different PSU or mains adaptor.
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Regards, John |
1st Jan 2022, 10:22 pm | #3 |
Dekatron
Join Date: Oct 2003
Location: Croydon, Surrey, UK.
Posts: 7,549
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Re: Strange wide vertical stripe
Can be caused by line pulses getting in to the video signal. If you have restored the TV, check lead dressing. Make sure that any wires from the CRT base socket are not draping across the video stages etc.
Could also be caused by local interference, the power supply to your Hedgehog for instance could be radiating excessively and the interference could be being picked up by the aerial cable (I had a similar problem from my digi-box PSU). Any external PSU's you have near the TV may cause problems.
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1st Jan 2022, 11:03 pm | #4 |
Dekatron
Join Date: Sep 2006
Location: Kilmarnock, Ayrshire, UK.
Posts: 5,420
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Re: Strange wide vertical stripe
It's off tune.
Try adjusting the fine tuner or the RF oscillator. Seen it many times before 405 was switched off.
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Cheers, Trevor. MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member Last edited by murphyv310; 1st Jan 2022 at 11:32 pm. |
2nd Jan 2022, 1:07 am | #5 |
Dekatron
Join Date: May 2010
Location: Greater Manchester, UK.
Posts: 18,676
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Re: Strange wide vertical stripe
A white vertical rope effect can by caused by EHT corona-discharge or "brushing" being picked up by the tuner. It's most noticeable at Band I frequencies.
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2nd Jan 2022, 10:04 am | #6 | |
Dekatron
Join Date: Sep 2006
Location: Kilmarnock, Ayrshire, UK.
Posts: 5,420
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Re: Strange wide vertical stripe
Quote:
The rope effect is different to what the OP has, it's far more noticeable than what he has. When you tune further toward and past the sound carrier the picture looks more sharp for some reason the fly back time then seems to be picked up by the front end. Some sets are more prone to this, TRFs are virtually immune but the more "modern" the likelihood is greater. If the alignment is good and the set not twiddled tuning for best sound then the issue completely dissapears. A set that has seen the phantom twiddler then it'll be worse. The effect is more noticeable on scenes like in the OPs photos. A quick adjust of the fine tuner will resolve the issue. If I'm wrong I'll drop off a Pye FV1 as compensation
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Cheers, Trevor. MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member |
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2nd Jan 2022, 1:46 pm | #7 |
Pentode
Join Date: Dec 2009
Location: Chatteris, Cambridgeshire, UK.
Posts: 176
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Re: Strange wide vertical stripe
I agree with Trevor.
It looks off tune and some slight alteration to the fine tuner (or local osc) should solve it. It also looks to have a little too much white after black/ black after white, again indicating slight mis-tuning. Unless alignment is out, the best overall picture should coincide with the maximum sound whilst tuning in. I must say, on some set's, the band is noticeable on a blank background. Don't expect to always eliminate it entirely.
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Andrew Last edited by PYE 405; 2nd Jan 2022 at 1:54 pm. |
2nd Jan 2022, 2:10 pm | #8 |
Diode
Join Date: Aug 2021
Location: Wilmslow, Cheshire, UK.
Posts: 5
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Re: Strange wide vertical stripe
It looks like it is struggling to pick up the luma value at the start of either the odd or even
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2nd Jan 2022, 2:26 pm | #9 |
Pentode
Join Date: Dec 2009
Location: Chatteris, Cambridgeshire, UK.
Posts: 176
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Re: Strange wide vertical stripe
Here is a similar, but reduced effect, on a set of mine. A slight band is seen just before the D of "DVD" on the screen. With a typical scene, it is not noticeable....
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Andrew |
3rd Jan 2022, 7:55 pm | #10 |
Octode
Join Date: Jan 2009
Location: Falmouth, Cornwall, UK.
Posts: 1,987
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Re: Strange wide vertical stripe
Some Humax HDR-T2 freeview boxes can produce this effect, it caused me much head scratching before realising the video source was the cause.
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Stephen _________"It`s only an old telly" ___ |
8th Jan 2022, 10:10 pm | #11 |
Triode
Join Date: Nov 2021
Location: Leighton Buzzard, Bedfordshire, UK.
Posts: 32
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Re: Strange wide vertical stripe
I remember seeing this off-tune effect back in the 405 days but cannot understand how it happens. Does anyone have a theory?
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John |
9th Jan 2022, 1:06 am | #12 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
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Re: Strange wide vertical stripe
The effect is caused by over-shoot of the trailing edge of the sync pulse. The result of the sharp transition between negative to positive.
As mentioned earlier in the topic it is most noticeable when the fine tuner is set to the point just before sound on vision. DFWB. |
9th Jan 2022, 2:22 pm | #13 |
Dekatron
Join Date: Sep 2006
Location: Kilmarnock, Ayrshire, UK.
Posts: 5,420
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Re: Strange wide vertical stripe
Hi.
Indeed David. The overshoot is caused by being off tune or a badly aligned vision stage and shorting out chokes in the video amplifier, in the main though being off tune.
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11th Jan 2022, 1:54 pm | #14 |
Triode
Join Date: Nov 2021
Location: Leighton Buzzard, Bedfordshire, UK.
Posts: 32
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Re: Strange wide vertical stripe
Thank you, that hadn't crossed my mind. I suppose it also depends on how well the flyback blanking works.
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John |