Software Support > GroovyMAME
Monitor losing sync: JPAC or CRT_emudriver?
big10p:
Hi
I have an intermittent problem on one of my cabs. Sometimes, the monitor image becomes completely garbled due to loss of sync. The sync light on the JPAC goes out. This generally happens a few minutes after booting. Sometimes it'll happen when my front end is being displayed (interlaced mode), but I get sync back when launching a game. Sometimes it's the other way around where the front end displays fine, but games are garbled.
I suspect a faulty JPAC but wondered if it's possible my CRT_emudriver installation is faulty, somehow. I'm using win7 64 with CRT_emudriver 2.0. Anyone else experienced this problem? I haven't included logs as most of the time it works fine, so can't be a setup issue.
Cheers.
brad808:
You can bypass the sync filters on the j-pac while keeping the video amp. Remove all the jumpers from the front then solder a small blob between pins 13-14 on the back of the jpac. If you do this it may solve your issue, if not you can eliminate the jpac as the culprit.
big10p:
Thanks for the info, brad808. Just to be clear, will doing this mean the JPAC will just directly pass-through any sync signal it gets? Bit worried about passing the 31khz signal to my arcade monitor at boot up.
Can I ask why you made this mod to your JPAC? Were you having the same sync issue as me?
brad808:
--- Quote from: big10p on December 04, 2016, 11:31:39 am ---Thanks for the info, brad808. Just to be clear, will doing this mean the JPAC will just directly pass-through any sync signal it gets? Bit worried about passing the 31khz signal to my arcade monitor at boot up.
Can I ask why you made this mod to your JPAC? Were you having the same sync issue as me?
--- End quote ---
Yes it'll pass everything through. Don't be worried about sending a boot signal for the few seconds before windows drivers kick in, or install atom bios to card.
Yes I had problems with J-pac sync circuit, I've had 5 now and all exhibit the same behavior so now I do this mod before I even install them. The sync circuit can't swap between 15-24-15 repeatedly for multisync monitors and needs to power down in order to regain sync. This is a big problem while using groovymame with auto sync monitors.
Also I've had in the past many times j-pac "randomly" drops sync of a signal it is displaying perfectly fine before. I wrote andy about this and he mentioned some people have had issues with the sync circuit not being able to properly identify certain modelines based on the sync pulse width being too narrow.
It was a problem that plagued my systems for a couple of years before I discovered this will solve it and not a single problem since.
If you want to test the jpac as well next time it happens, unplug the usb and plug it back in, see if it regains sync.
big10p:
I do remember a while back when this happened, I unplugged the VGA cable and plugged it back in, then the JPAC got sync again. Thanks again.
Navigation
[0] Message Index
[#] Next page
Go to full version