Controls ground with JPAC and original powersupply removed.

[robbbby]

I've searched a bunch and can't find a proper answer.  The topic seems to come up but the threads never get an actual answer.

I have an old neogeo mvs cabinet.  Pulled the original power supply out to run mame.  The grounds on the jamma connector going to the controls originally come from (as far as I can tell) the -5VDC of the factory power supply.  With the power supply removed those black wires now just end at the connector that used to plug into the PSU.
So now with a JPAC installed, the JPAC itself has a ground terminal for added buttons, but what about all the original stuff?  Does the JPAC send a control ground back out through the gnd wires on the jamma connector?  I'm confused where the original buttons/joysticks that use the ground from the jamma harness are actually going to get a ground from now.

[robbbby]

In case anybody is ever searching for the same question, all grounding for the controls now comes from the PC with the JPAC plugged in.

[CheffoJeffo]

  for taking the time to post the answer