maybe it is mixing concepts about monitors?
if you read here, it "alludes" that the j-pac has an amp-
https://www.ultimarc.com/vidamp.htmland that is cross-referenced here-
https://www.ultimarc.com/jpac.htmlI compared my j-pac which was likely purchased in 2012 with the current pic and it looks identical.
I am having trouble finding the ultimarc info i used when trying it out on my g07 pacman cabinet. where it said j-pac didn't have an amp.
i'll keep looking.
the doc I'm seeking talked about the 15k and 31k jumpers.
ah, here it is. it does say it amplifies it to arcade monitor levels but doesn't process it in any way.
per my test below...it is not amplified enough whatever their version of amp means.
https://www.ultimarc.com/jpac2.html----
using the hdmi to vga adapter to j-pac the image was washed out and very dim and wouldn't sync.
the arpicade was bright and sync'd solid.
Used the same exact raspberry pi with the same sd card image, so the config.txt was identical in the test.