Converting mvs cabinet to jpac/laptop setup: couple of issues

[comatsu]

I've removed the mvs pcb from my cabinet and am attaching a laptop through a J-Pac (got a bunch of thread all around the board asking for help with the different aspects :p).

Now everything is slowly coming together but I have 2 main problems left:

1. I disconnected the power supply and connected the monitor (hantarex polo) directly to the ac mains (as nothing else needs power since it will be all going through the laptop.  However this means that all the ground wires in the cabinet now lead to an inactive power supply which is not turned on (or even connected).  Is this a problem?  How can I solve it?

2.  My laptop has an internal 4ohm stereo speaker.  If I disconnect this (it has 2 wires going in, one red and one black) and connect its wires to the speaker+/speaker- screw connectors on the J-Pac will that give me sound out of the cabinet speaker?  The speaker on the cabinet is 8ohm and mono however.

[comatsu]

Any suggestions on this?

[BobA]

Since you are not using the power supply the grounds on it are just a termination point and should be fine.

Ultimarc Quote

JAMMA cabinet speaker routed to screw connectors for wiring to powered sound card or hacked PC speakers.

So connecting the wires that go to your laptop speaker to the speaker inputs on the jpac should work or you could just plug in a audio cable to your speaker jack (if it has one) on your laptop and route those wires to the jpac card.  If you need more volume you might require an external amp but try the direct connect first.

[comatsu]

Thanks BobA.

Just to clarify - the power supply will not be connected to the ac mains. Is that still ok as a termination point?

[BobA]

You should ground to the ground on your power outlet so the ground on the PS does not become a true ground until it is connected to the ground on your power cord.

[comatsu]

Understood now thanks.

This leaves me with the problem that since the PS is disconnected, the cabinet is without an actual ground.  Any simple way I can solve this?

[BobA]

Yes use a grounded power cord (3 wire) to supply your cab.  Tie the ground to the ground terminal of your PS.