JPAC advice needed

[RygarR]

One of my JPACs looks like it's started to fail

When I boot the PC, it's out of sync, but it's got nothing to do with the trimmers on the monitor. Start a game, and sync is fine. Quit back to the game selector page, and sync is restored. Bit of a PITA. This is a relatively recent model. Anyone got any advice?

 

[Flinnster]

Check your jumpers. Make sure 31khz one is on, and 15khz one is on. This enables the safety mode on 640x480 VGA output.. often used when windows is booting up etc..

Your game selector page might not be using true 15khz game resolutions is my thinking.

 

[big10p]

Sounds like it could be the issue I reported a few years back...

http://forum.arcadecontrols.com/index.php/topic,152488.msg1596505.html#msg1596505

 

[RygarR]

Thanks both!

This happened to me before on an ancient PS2-only JPAC, which eventually became unusable. Definitely up for soldering the blob onto the pcb.

Cheers!

 

[Retroman839]

Cool I got one with this problem thanks will do this asap

 

[bjt42]

I get this problem once in a blue moon too. Sync light on JPAC flashes madly like it can't lock on. Keep meaning to do the solder blob mod to bypass the sync circuit. With and Atom15 flashed card and correctly set up PC you don't need to worry about >15khz signals from the PC anyway.

 

[RygarR]

Sounds like it could be the issue I reported a few years back...

http://forum.arcadecontrols.com/index.php/topic,152488.msg1596505.html#msg1596505

BEFORE:

I've marked the pins to join with red ink.

I'd also taken the jumper off the front (I only seemed to have the one, on 15 kHz). If you have more than one, take 'em all off.

AFTER

Now that's a 'blob'! It's also a very blurry pic... soz :-

RESULT:

Sync problem seems to be cured!

However, you guys have now got me worrying about the ATOM 15 situation...

...In reality, with my MAME PC booting to front end in less than 20 secs, it's unlikely to ever spend more than a second or two in 31kHz mode, which I doubt would harm the monitor.

But would it be worth doing anyway?

And if so, is it something that can be done on the fly - ie. by temporarily switching out of GroovyMame to Windows and running the flash programme? Or would I then need to re-install Windows, CRT Emudrivers, GroovyMame and all the ROMs / Videos etc.?

 

[big10p]

I flashed ATOM-15 just to be on the safe side. It's pretty easy and you don't need to re-install anything as all you're doing is patching the video card BIOS.

http://geedorah.com/eiusdemmodi/forum/viewtopic.php?id=64

 

[Flinnster]

If my orientation on that VGA connector is right, thats just combining the syncs by the looks of things. Those pins are H-sync and V-sync?

 

[r-type]

I've done this fix in the past too.

 

[RygarR]

It does seem to have solved the problem...

 

[RygarR]

Cheers Big10p.

In that case, I might as well!

I flashed ATOM-15 just to be on the safe side. It's pretty easy and you don't need to re-install anything as all you're doing is patching the video card BIOS.

http://geedorah.com/eiusdemmodi/forum/viewtopic.php?id=64

 

[big10p]

If my orientation on that VGA connector is right, thats just combining the syncs by the looks of things. Those pins are H-sync and V-sync?

Yes, think crt_emudriver outputs composite sync on the h-sync line. This seems to confuse the J-PAC sometimes. Combining syncs fixes it.

 

[cools]

It only outputs composite sync if you enable it in the driver, otherwise the output is separate H V sync.

 

[Flinnster]

So.. potentially if you fix the driver, you don't need to solder?