Double Dragon Video Sync Issue

White Devil said:

If the lowest resistor I happen to have is 4.7k would it be okay to try that? Or better to order the 1k?

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Anything between 1k and 10k should be fine.

Xian Xi said:

TVs are made to display a 60hz signal. Depending on the brand it will have a wider scan range, I don't know if they will go down to 57.5hz though as some have trouble at 59hz.

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I ain't that bad afterall to have PAL tv's ^_^'
They can take all the "hz punishments" eheh!

Atro said:

I ain't that bad afterall to have PAL tv's ^_^'
They can take all the "hz punishments" eheh!

Click to expand...

Think if I plug this into my LCD TV and select PAL it'll make a difference?

White Devil said:

Think if I plug this into my LCD TV and select PAL it'll make a difference?

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Not really sure.

I just quoted James because PAL TV's can have a wider range of refresh as they output from 50hz onwards. So the 57'ish something are covered. Doesn't mean it'll work well on every tv set tho.
But you should give a try.

Xian Xi said:

Anything between 1k and 10k should be fine.

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Didn't help.
Yet, if I hold the exposed wire with each hand on the in and out for the sync from the sync stripper the picture is perfect. No issues. Then when I let go it's crazy. I think the picture jumping has something to do with when the sprites move

This is just a guess....you may be coupling 60Hz mains noise into the device and also feedback while your holding the two leads.

Only way to know for sure the exact effect would be to compare the two different inputs to the 8200 with a scope.

The human body can act as a capacitor, resistor, inductor and antenna, so without a definitive reading it's just hunches at this point.

bustedstr8 said:

This is just a guess....you may be coupling 60Hz mains noise into the device and also feedback while your holding the two leads.

Only way to know for sure the exact effect would be to compare the two different inputs to the 8200 with a scope.



The human body can act as a capacitor, resistor, inductor and antenna, so without a definitive reading it's just hunches at this point.

Click to expand...

Scope? What's a scope? If it's something I need to buy can you post a link?

An oscilloscope, they range from tens of dollars for PC based ones to thousands for benchtop models.

Damn... I don't have a PC...

I recently got a double dragon 3 in exchange for helping out at my buddies shop. My PVM wouldn't sync to it, and it usually syncs to everything (including composite video). I cleaned the board a bit, checked traces, etc. to no avail. I tried an extra 220 ohm resistor on video sync (I use 220 ohms of resistance on RGB and Sync each already) with no improvement.

Then I tried a 220uf cap, negative toward the display (as is normal). It syncs perfectly now. My last resort was going to be a lm1881 but the cap seems to straighten it out. Basically it's JAMMA sync pin -> 220 ohm resistor (only used because it's a supergun) -> +[220uf cap]- -> display.

That's cool. Wonder if the same method would help with oddballs like Raiden Fighters.