J-Pac sync issues

[RygarR]

Hi Everyone,

Had my two MAME cabs fired up a fair bit over the hols. Both are based on MAMEd PCs and J-Pacs. While I've had them on for hours on end previously with no issues, the J-Pacs on both of them are now periodically losing sync. The time it takes for this to happen is fairly random, and the effect varies. Could be, they'll last for 2 or 3 hours with no probs at all, and sometimes it's just the Frontend screen that gets lost, with the games themselves syncing up OK.

I've read elsewhere on the web that this might be a voltage issue. And right enough, I have mucked about with the USB ports and the stuff plugged into them over the past couple of months.

I was wondering though, if it would be possible to use a Y connector to link the J-Pac and PC with a separate USB power adapter? Or would that risk shorting or blowing components?

Any advice welcome...

 

[minwah]

What do you mean by 'losing sync'? Are you talking about the monitor / video signal?

If so, how are you making your video 15khz...ArcadeVGA or Soft15khz or similar?

 

[RygarR]

Hi Minwah,

I mean that the image stops being stable and starts to roll as if the vertical and or horizontal synch pots have been twiddled - which they haven't. I've tried adjusting the pots when this happens, but nothing happens

I'm using software solutions for both. One is Soft15Khz. Pretty sure the other is on CRT emu-driver.

 

[minwah]

Hi Minwah,
I mean that the image stops being stable and starts to roll as if the vertical and or horizontal synch pots have been twiddled - which they haven't. I've tried adjusting the pots when this happens, but nothing happens

It sounds a bit like the v-hold, but if you've tried that...

Does your JPAC have the sync led's on it?

I think to rule out the power problem I would get a powered USB hub to go between PC and JPAC, and don't plug anything else into it.

 

[RygarR]

A powered USB hub. I didn't realise there was such a thing! Sounds ideal though. I'll give it a try.

Cheers

PS. When the frequency goes haywire, so do the sync LEDs on the jpacs.