vga flat screen monitor jitter

i have an old arcade game with a bad monitor, blown out flyback that is unobtainable. . tough to find a working 13 inch cga unit, and harder to find one compact enough to fit . anyway, ive tried using a cga to vga converter board ( GBS 8200 ), its commonly used and has worked well in the past. im using a 13" vga flat screen .

the vga has horizonal jitter, quite bad. no way to adjust out. somebody suggested plugging a spare vga cable into the vga input on the converter board. that reduced it 90%, but on a reboot its back , and cant get rid of it. the game works nicely when hooked up to a spare 19" cga crt. i also tried a vga crt, same jitter.

im thinking the added cable adds a load that stabilizes the horz sync, and maybe there is a way to make it more stable? there is only h sync out, no vert. vertically, there is no jitter

thanks

 

On Saturday, August 5, 2017 at 10:37:27 AM UTC-4, mhoo...@gmail.com wrote:

i have an old arcade game with a bad monitor, blown out flyback that is unobtainable. . tough to find a working 13 inch cga unit, and harder to find one compact enough to fit . anyway, ive tried using a cga to vga converter board ( GBS 8200 ), its commonly used and has worked well in the past. im using a 13" vga flat screen .

the vga has horizonal jitter, quite bad. no way to adjust out. somebody suggested plugging a spare vga cable into the vga input on the converter board. that reduced it 90%, but on a reboot its back , and cant get rid of it.. the game works nicely when hooked up to a spare 19" cga crt. i also tried a vga crt, same jitter.

im thinking the added cable adds a load that stabilizes the horz sync, and maybe there is a way to make it more stable? there is only h sync out, no vert. vertically, there is no jitter

thanks

correction. with the spare vga cable, it still is 90% better. the second time i plugged the spare into a second card i had on the bench, like a schmuck. plugging into the right card, and its close

 

On Saturday, August 5, 2017 at 10:48:25 AM UTC-4, mhoo...@gmail.com wrote:

On Saturday, August 5, 2017 at 10:37:27 AM UTC-4, mhoo...@gmail.com wrote:
i have an old arcade game with a bad monitor, blown out flyback that is unobtainable. . tough to find a working 13 inch cga unit, and harder to find one compact enough to fit . anyway, ive tried using a cga to vga converter board ( GBS 8200 ), its commonly used and has worked well in the past. im using a 13" vga flat screen .

the vga has horizonal jitter, quite bad. no way to adjust out. somebody suggested plugging a spare vga cable into the vga input on the converter board. that reduced it 90%, but on a reboot its back , and cant get rid of it. the game works nicely when hooked up to a spare 19" cga crt. i also tried a vga crt, same jitter.

im thinking the added cable adds a load that stabilizes the horz sync, and maybe there is a way to make it more stable? there is only h sync out, no vert. vertically, there is no jitter

thanks

correction. with the spare vga cable, it still is 90% better. the second time i plugged the spare into a second card i had on the bench, like a schmuck. plugging into the right card, and its close

i put a 4.7 k resistor in line with the sync and it seems to be fine now, no dummy vga cable needed. i tried different values, 4.7k works well.

 

[Tim Schwartz]

Good morning,

While you have seemed to have fixed your problem, you could have
considered posting the make, model and part number of the flat panel you
needed, as there are plenty of people who have old, obsolete parts
around the shop that they are thrilled to see get used.

While that does not mean that this should become a parts for sale site,
it is also not a terrible thing to ask about a part on occasion.

Regards,
Tim


On 8/5/2017 10:37 AM, mhooker32@gmail.com wrote:

i have an old arcade game with a bad monitor, blown out flyback that is unobtainable. . tough to find a working 13 inch cga unit, and harder to find one compact enough to fit . anyway, ive tried using a cga to vga converter board ( GBS 8200 ), its commonly used and has worked well in the past. im using a 13" vga flat screen .

the vga has horizonal jitter, quite bad. no way to adjust out. somebody suggested plugging a spare vga cable into the vga input on the converter board. that reduced it 90%, but on a reboot its back , and cant get rid of it. the game works nicely when hooked up to a spare 19" cga crt. i also tried a vga crt, same jitter.

im thinking the added cable adds a load that stabilizes the horz sync, and maybe there is a way to make it more stable? there is only h sync out, no vert. vertically, there is no jitter

thanks