Page 1 of 1

JPAC and MiSTer Highly Saturated Calibration or MiSTer?

Posted: Mon May 03, 2021 6:22 pm
by Escape-To-88
Wasn't sure where to put this. Hooked up my MiSTer to my hori Egret 2 today and worked a treat. However as you can see by the attached picture the reds were extremely high and the whole picture was super bloomy. Now, I calibrated my monitors after they were washed and recapped specifically for GroovyMAME and the picture was amazing. So what I am asking is, is this over bright, red heavy image an issue of the MiSTer's output or is it simply that I have to spend a couple of hours recalibrating again? I suspect I need to recalibrate and haven't yet tried my vert E2 which I calibrated slightly differently but thought I'd ask before I spend an afternoon diving into the back of the machines. Cheers

Re: JPAC and MiSTer Highly Saturated Calibration or MiSTer?

Posted: Sun May 23, 2021 1:18 am
by larvanoir
I have the exact same issue. I'm thinking that this is a result of the video amplifier in the J-PAC, that is meant to boost a PC video signal from 0.7 to 5V. I haven't found a way to disable the on-board amp, maybe there's a way to attenuate the signals between the IO board and J-PAC? Any ideas are welcome.

Re: JPAC and MiSTer Highly Saturated Calibration or MiSTer?

Posted: Sat Jun 26, 2021 2:06 pm
by wodmarach
This and many other problems with the JPAC method is why I've ended up deciding to wait until the mistercade boards become available.

Re: JPAC and MiSTer Highly Saturated Calibration or MiSTer?

Posted: Tue Jul 20, 2021 9:50 pm
by larvanoir
In the end I sorted this out by adding trim pots to the R / G / B lines out of the JPAC to the JAMMA harness. Just a small adjustment brought the image into normal range. I've found this also useful for arcade boards that output video too "hot" for a certain monitor (CPS2 in my case), it's easy to add to an extension harness.

IMG-6495.jpg
IMG-6495.jpg (1018.35 KiB) Viewed 2032 times

Re: JPAC and MiSTer Highly Saturated Calibration or MiSTer?

Posted: Tue Jul 20, 2021 9:55 pm
by mhartman
I use an hdmi to vga converter with my JPAC and it works fine.

Re: JPAC and MiSTer Highly Saturated Calibration or MiSTer?

Posted: Thu Oct 13, 2022 10:27 pm
by dethreign
larvanoir wrote: Tue Jul 20, 2021 9:50 pm In the end I sorted this out by adding trim pots to the R / G / B lines out of the JPAC to the JAMMA harness. Just a small adjustment brought the image into normal range. I've found this also useful for arcade boards that output video too "hot" for a certain monitor (CPS2 in my case), it's easy to add to an extension harness.
Hi everybody, I'm running my MiSTer through Direct Video to a JPAC and running into some issues. :(

It looks like I'm having the same over-saturation issues you guys are with my JPAC, a couple questions:

What rating trim pots are those? 10k?
Did you take the RGB lines from the chip out of circuit? Cut/Solder traces back to RGB out on JAMMA Connector?

Also, I'm noticing when I plug in my JPAC through the USB, it's like the JPAC loses sync and the picture scrambles, anyone else hear of this?

Pic for reference

Edit: After some poking around with a multimeter, I've come to the conclusion the JPAC is faulty, the voltage on the JAMMA Edge is only reading 0.3 volts across the RGBs lines.
oversat.jpg
oversat.jpg (7.15 MiB) Viewed 1077 times

Re: JPAC and MiSTer Highly Saturated Calibration or MiSTer?

Posted: Wed Apr 05, 2023 7:23 pm
by larvanoir
dethreign wrote: Thu Oct 13, 2022 10:27 pm

It looks like I'm having the same over-saturation issues you guys are with my JPAC, a couple questions:

What rating trim pots are those? 10k?
Did you take the RGB lines from the chip out of circuit? Cut/Solder traces back to RGB out on JAMMA Connector?

It's been a while, sorry for the late post. Maybe this is good for somebody's situation, I made these little adapters to adjust the video signal some time ago and they've been very helpful.

It's just a breakout JAMMA pcb with three 1K Ohm pots for the R,G,B lines. I also added voltmeters to 5V / 12V for extra convenience. They work great in my candy cabs which have a JAMMA switcher for multiple systems. If you're switching between, say, NeoGeo, CPS-2 and MiSTerCade, you'll notice that each has different contrast levels. With this I can adjust for each board at the JAMMA connector and don't need to fiddle with the CRT levels. PCB and edge connector are from arcaniac.com

IMG-7605.jpg
IMG-7605.jpg (345.41 KiB) Viewed 199 times