|
Losing v-Sync when using J-pac
#352903 - 04/12/16 09:14 PM
|
|
|
Hello,
So I posted about this 4 years ago but sadly on top of not finding a fix I also haven't seen my arcade cab since then as its stuck in my parents garage half way across the country. However its really been bugging me recently and I thought I'd see if anyone had any advice on a potential fix I have
Quick recap of my issue.
If I direct connect my vga port from my HD4xxx gfx card to my hantarex 9110 monitor then everything works fine. All resolutions look great.
If I connect it to the j-pac then interlaced resolutions fail to hold their v-sync. See following youtube clip
https://www.youtube.com/watch?v=a9nvvE5n0BI
Now, no one seemed to know why at my original posting but I theorised that either the jpac was introducing some kind of noise when it boosts the vga output from 1v to 5v (although correct me if I'm wrong but this should only be on the rgb pins right?). Or my monitor simply can't handle the stress of a 5v input (Note. it has a knob to adjust between different strengths of input. Turning it while getting the boosted input does not solve the issue leading me to lean towards the first theory)
So, unless anyone sees this and has new ideas, I figured I'd just grab a breadboard from my local electronics shop and wire the direct link vga up via some transistors while at the same time also connecting the vga (I'd split it) to the j-pac. When it passes through a 5v line to the Jamma connector I can route that to the transistors to allow the direct connection through. Thus having the j-pac benefit of protecting my monitor without the signal boosting parts. I'd naturally have to cut and junction the jamma connector to prevent the jpac outputs making it to the screen. Seems a shame but not sure what else to do at this point.
Does that sound like it'd work? I have some things I'm not sure about.
1) I've forgotten all of my electronics from school so I'd need to work out exactly what transistors to buy and if I'd need other components (resistors etc) to get it to work.
2) Can anyone see any issues with splitting the vga signal like that.
3) does the j-pac cut all lines out when the signal is invalid? I need a reliable way to tell that its legit so if the 5v rail is always live I might be a bit screwed 
Cheers for any help you can give
Paul
|
|
|
|
Re: Losing v-Sync when using J-pac
[Re: Pod]
#352907 - 04/12/16 10:58 PM
|
|
|
You shouldn't have to do any of that. I'm not understanding something. Sans the jpac, what display are you connecting your card to? I assume you're using a jpac because you're connecting to a jamma interface in your cab. Typically, that's composite sync or something, and doesn't like some signals.
|
Scifi frauds. SF illuminates.
_________________
Culture General Contact Unit (Eccentric)
|
|
|
Re: Losing v-Sync when using J-pac
[Re: Pod]
#352929 - 04/13/16 04:03 AM
|
|
|
|
|
|
Re: Losing v-Sync when using J-pac
[Re: Traso]
#352945 - 04/13/16 08:35 AM
|
|
|
A hantarex 9110. When I say direct connection what I mean is I've spliced the wires near the monitor and attached a vga cable. This is how I used to run it back when I had an arcade vga before I upgraded to the ati 4xxx and jpac combo.
However I can't exactly tell you what wire went where as it was so long ago. I followed a guide on arcade controls or possibly the one on ultimarcs site. Quite likely I've combined h and v sync together as Andy suggests
Perhaps the jpac does something else other than just boost the signal? But as mentioned if I run it via the jpac and choose any non-interlaced mode it's perfectly fine.
Paul
Edited by Pod (04/13/16 08:53 AM)
|
|
|
|
Re: Losing v-Sync when using J-pac
[Re: Pod]
#353097 - 04/17/16 09:00 AM
|
|
|
I've never bothered with interlaced signals. Seems like a headache all for a crappy image.
|
Scifi frauds. SF illuminates.
_________________
Culture General Contact Unit (Eccentric)
|
|
Index 
Threaded 
Losing v-Sync when using J-pac
Reply
[Re: 
