MiSTer FPGA Forum

I've been trying to troubleshoot this for a couple weeks now but for some reason I don't get the color Green in the video output for MiSTer when connecting it to my arcade monitor.
I have IO Board 6.0 to Ultimarc VGA Amplifier to WG K7500
Other VGA devices including a Raspberry PI and PC output correctly when run through the amp. I am also able to get green when running through a VGA to component transcoder that I have. I've tried toggling options like csync and the SOG switch in every way I could think of but strangly, neither of those options make any difference whatsoever. I've assured ypbpr is disabled as well.

I'm wondering with the behavior of the Q1 component and the SOG auto mode is. The green line has more components then the other two video signal lines and I wonder if there is some way to bypass them since I do not need SOG for any of my current setups. For troubleshooting sake, the next thing I"m going to try to do is connect the red video line to the green line on the amp/monitor to see if the behavior flips. I assume this should confirm that there is something the mister is doing that the amp doesn't like with that particular line.

I am having a similar but slightly different problem with the I/O Board and another Ultimarc product, the J-PAC (which includes an amp i believe is very similar, if not basically identical, to yours). In some scenes (darker scenes, mostly) green comes through fine, but in brighter scenes the green drops out, leaving the color more red/purple. Seems like a related issue.

That's interesting because mine was effectively the opposite. If I use a test pattern with %100 green it comes through. I was really thinking about picking up a J-Pac since Porkchop reported using it himself.
The circuits on the two products are supposedly using the same amp but I think the J-pac has additional protection and controller chips. Mine is just a single IC with resisters and few capacitors. The resisters are surface mount and I thought about replacing them with pots to see if I could make adjustments but... I don't know that much and probably would need an oscilloscope to troubleshoot further.

So I bought a HDMI to VGA dongle to rule out that the J-PAC was the issue and sure enough colors look perfectly fine when using direct video through the J-PAC. I think you are absolutely right that the SOG switch/capability is causing the issue with green - if someone knows how to disable the SOG functions on an I/O board please let us know.

I have an Astro City (Nanao MS8 or 9, not sure yet) and I felt like I was going crazy because everything white is just yellow. Like crazy yellow through the I/O board and the new J-Pac.

Any solutions here?

I had (have) the same issue with green missing in one SOG setting and colors being off on the other setting, but I have two MiSTers. The problem only occurs on one of the two, which leads me to believe that this is a hardware fault with one the the I/O boards.

They are I/O boards 5.5 and 5.6XL. VGA Out worked fine on either and the fault occured on the 5.6XL one day.

Threepwood interesting, so perhaps it's a manufacturing fault rather than a design fault? Did you get both of your I/O boards from the same seller?

Mmsiphone wrote: ↑Wed Jun 17, 2020 4:49 pm Did you get both of your I/O boards from the same seller?

No, from different sellers and they both worked at first, but then one showed this flaw. First I suspected an update to have caused it, but since my second MiSTer that I update just the same works fine, a hardware issue with the I/O is quite plausible.

Considering that this seems neither super rare nor common, maybe there is a part that can be susceptible to this kind of fault.

To anyone still following this thread, an update on this:
I picked up a SCART2ARC30 (found here: https://etim.net.au/shop/shop.php?crn=2 ... how_detail ) and it doesn't have the problem I had with the Ultimarc amp. All colors come through.
I also had to make a vga to scart cable and enable csync in order to use it but it works very well.

Just to chime in I am so glad to find this thread, I was going a little mad with trying config and monitor adjustments on both a blast and egret 2 with my Jpac setup. (Same problem as relay01)

Figured it couldn't hurt to bump this thread and mention I was having this issue on a newly purchased mister with I/O ver6.1.

I will try and borrow a friend's older 5.5ish I/O since he is running a jpac with no issues and make sure the issues follow the I/o and not the jpac. Also the analog out works perfect on my pvm, but that monitor will really display almost whatever is thrown at it.

Hey guys having the same issue here on I/O board v6.1. Has anyone tried running 5v to the amp and leaving the 5V jumper off on the I/O board?