Bypassing J-PAC's video amp ?

[Level42]

Wanted to ask if there is an easy way to (temporarely) bypass the video amp on the J-PAC. Of course I can wire my monitor directly to my ArcadeVGA, but that would mean extra wiring to the Jamma connector or taking off the leads.

I think my Hantarex doesn't really like the 5V signal coming from the videoamp. The colors seem to be too "screaming" (I'd define it as too much dynamic between dark and light), and want to see what results I get from the ArcadeVGA directly.

So I'm looking for something to bypass on the J-PAC itself.

Of course I could ask Andy, but maybe we can keep his mailbox a little emptier this way ?

[menace]

I had a JPAC where the small chip blew and that effectively disabled the amp circuit--what else it did isn't certain but if you don't care about your jpac you could pull that little chip and see.  Keep in mind that mine did still function (all keyboard passthrough etc.) with a bad chip but whether the chip was completely bad or just malfunctioning isn't known.

[RayB]

Regarding that chip, I would worry about removing the cut-off feature that blocks "bad" signals if you removed or killed that chip.

I too felt the same way about the video being too saturated (CGA Vision Pro II). I had emailed Andy about and he said it might be possible to cut or bypass some resistors or something like that. He never emailed me back with the way to do it, but I also did not follow up with him.

I wonder if adjusting the R G and B "drive" potentiometers on the monitor would help? I wouldn't want to mess those up though. It's hard to get a good color balance.

[Level42]

Exactly my thoughts, it's not smart to start fiddling with these settings before you know the source is good.

Andy already indicates that (some) Hantarex monitors are OK with the  1V signal directly from the ArcadeVGA so that maybe the case for me, however this is a real "old" arcade CRT so you'd expect it to want the 5V signal. Think I might be able to trace the paths on the J-pac and bypass the RGB lines temporarely with wires.

Removing the chip, don't think that would be any help, normaly an amp is in the line of the path of the singal so I'd expect to have no signal at all when I would remove it ?

Andy are you around ?