MVS 4 slot in Watchdog mode... works fine if I use the original arcade JAMMA Harness

Hi there!

Gosh, loving it here everyone is super helpful with my SuperGun Pet project, thanks in advance as I am just a gal with the internet at my disposal and some basic soldering skills.

Quick Background:

I am making a SuperGun to power my MVS (With the MVS pinout on the JAMMA harness (silly I know but I can't find a JROK that is available for purchase and a SuperGun is cool enough for now)

I am getting RGB, - and Sync signals from the board converted to a CGA to VGA adapter (You know, the ones from China?)

I have the original MVS JAMMA Harness and I can switch back and forth to check if I broke something lol (The images come up perfectly if I use the stock Harness)



The Problem:
1) The screen is showing blocky graphics (aka Watchdog)

2) I checked the PSU connections (5V+, 12v (no need for -5v on MVS) and I am getting a solid connection

3) Checked my on/ off switch and there is no bottleneck in power flow.

4) Power draw off the MVS is solid (Soldered a cable off the 5v+ Cap behind JAMMA pin 4-5)

5) Cleaned the cart contacts and the pin connectors on the MVS

What do you think it could be?
Its not a screen of death as the MVS works fine in the original MVS JAMMA harness

I can check power once more??

Its almost as if there is a power issue?

Looking forward to hearing your ideas

-Tengugurl

I would say that it isn't getting enough power. Check the gauge of the wire on the power pins of your new harness. If it's a harness from China I can almost guarantee the wiring is not good enough for voltage and ground connections.

Check voltage at the JAMMA edge under load and then check at one of the ICs furthest away from the JAMMA edge (just find out what is +5V and GND).

Good thinking! You are so right, I do have a Chinese JAMMA harness and I am using 22AWG on the PSU ports - on/off and GND Cant wait to get home and give this a go, hopefully I have some good news
Where as the JAMMA 5v+ and GND should be thicker... never would have thought of that without your help

Thanks much!
Tengugurl

I am waiting on the JAMMA harness I got off of Ebay Twisted Quarter, hopefully that fixes it thanks so much Pulstar