Clean the cartridge slot and cart edge connector.
I know you said it looks fine but after 20 years of disuse, oxides can build up. Not always visible.
Have you checked the PSU? Make sure it's strong and steady.
Have you tried it with and without controllers attached?
Give the board a good brush and a blast with an air duster or compressor, just to make sure there are no little pieces of shit shorting something out.
Thanks for the reply.
I had a NES cleaning kit... the one that cart slot cleaner, I cut it into pieces so I can use it on the Jag. I used 91% Isopropyl Alcohol (it's what I have), I used a Q-tips to apply it to the NES cleaner. I would clean the slot, see there was dirt on it, I would clean the connector then reapply with the Q-tip, I kept doing it, like 5-7 times till no signs of dirt. Should I be doing anything else to clean this correctly ? I've been using Brasso to clean my older carts (NES mainly or anything with brass connectors). I'd be tempted to use that but, it would make a big mess.
The carts I tried both were cleaned on the edge and polished..
As for the power supply, I cant find the original JAG one but, I am using (suggested) Sega 1602-1 power cord. It's been confirmed that would work. I know it works perfectly on the Sega Genesis (was playing Sonic 2 with it the other day). I plan on buying a OEM style at some point.
I tried with out a controller attached, same exact result.
The other day troubleshooting it, I completely pulled it apart, blew everything out (it really does look new now, no more dust). I even polished the connectors to confirm there is no video connection issues.
These are things I have tried already before posting.
Any other thoughts to try ? I really want to get this back up and running.
Edited by TheCoolDave, Mon Oct 22, 2018 9:00 PM.