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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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27th Mar 2017, 10:49 pm | #1 |
Diode
Join Date: Mar 2017
Location: Oxford, Oxfordshire, UK.
Posts: 3
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Problem with BVM-D24E1WU
Hi,
I'm new to the forum so my apologies for starting out with a request for help but I've drawn a blank elsewhere. I've had my Sony BVM D24E1 for about 18 months and generally speaking the image quality is amazing - especially for old gaming equipment. The one minor annoyance is a series of red lines that arc across the screen when displaying a 480i image (note: 480p and 720p are perfect no red lines so looks like an RGB issue). I've upload some images to show the effect it can be seen at the border when video output comes from a console or across the whole screen when no video is connected. I'm hoping someone can advise what might be causing the problem and possible solution? Thanks in advance John |
29th Mar 2017, 12:10 am | #2 |
Octode
Join Date: Jan 2013
Location: Barnsley, South Yorkshire, UK.
Posts: 1,517
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Re: Problem with BVM-D24E1WU
These look like 'flyback' lines. These become visible most commonly because either 1) the blanking circuit is faulty and not cutting off the tube when the beam is retracing from the bottom of the screen back to the top or 2) the first anode (US screen grid) voltage is set too high; this is sometimes done to assist a failing tube to try and drag a bit more beam current out of it or to push the 'curves' of the three beams to a point where they track better.
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29th Mar 2017, 12:35 am | #3 |
Dekatron
Join Date: Dec 2007
Location: Haarlem, Netherlands
Posts: 4,185
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Re: Problem with BVM-D24E1WU
Since they only appear on 480i, I'd look for some fault in the mode switchover affecting the voltages to the CRT. Will have to study the schematic whether this makes any sense.
Edit: it makes sense. It could be as simple as an adjustment. Last edited by Maarten; 29th Mar 2017 at 12:46 am. |
29th Mar 2017, 1:16 am | #4 |
Dekatron
Join Date: Dec 2007
Location: Haarlem, Netherlands
Posts: 4,185
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Re: Problem with BVM-D24E1WU
Two other thoughts:
- A starting point for measuring would be the 1145V at Q201 on the PA board, to see if it remains stable in all modes. The same goes for the actual G2 voltage, but that requires a meter with a high input impedance. - check (given the age and Sony's reputation) for leaky (SMD) capacitors on the small signal and control boards. Last edited by Maarten; 29th Mar 2017 at 1:27 am. |
29th Mar 2017, 11:18 am | #5 |
Diode
Join Date: Mar 2017
Location: Oxford, Oxfordshire, UK.
Posts: 3
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Re: Problem with BVM-D24E1WU
Thanks for the suggestions. I've found a firm in Woking that still services Sony CRT monitors so I've passed on your advice to them. Will let you know if I manage to get the issue resolved.
Cheers, John |