Coin Selector Grounding

[Steveearle86]

Hi there,
I'm new to this forum and am in the process of building a MAME cabinet

I have a question regarding the coin selector. I am looking at a CH926 which seems to do what I want, that is allow input of multiple coins and set a value for 1 credit. I want to power the coin selector through the PC's PSU.  I can see from the wiring diagram that the white wire is the 'coin' wire that I would wire to my USB interface which would simulate the key press and that the red wire is the 12V power wire that I would wire to a molex plug and connect to the power supply.

I have two questions:
where should I connect the ground wire - to the molex plug and into the PSU? Or to the daisy chained ground wire that is connected to all the other push buttons?
Also, what is the grey "counter" wire used for?

I live in the UK if that has any relevance,

Many thanks
Steve

[Kevin Mullins]

where should I connect the ground wire - to the molex plug and into the PSU?

Yes.
+ (red) and - (blk) both go to the PSU 12v source.

Also, what is the grey "counter" wire used for?

That goes to the negative side of the coin counter / coin meter if you have one installed for counting the number of coins that have dropped through the mech.
The other side of the coin meter goes directly to the positive side of the 12v power source.
(verify your coin meter voltage requirement, some meters are only 5v) 

[Steveearle86]

Hi there,
Thanks for your reply. I believe the unit I am looking for has a 'coin counter' integrated, it uses pulses and has an AP mode, which if I understand correctly, means I can give each coin a 'pulse' value and set what pulse value a credit equates to.

In which case, Does this mean I would not need the grey wire?

After doing a bit more research, it looks like, as you say, the USA encode I am looking at using runs @ 5v. Does this mean I need to use some sort of diode on the white coin wire between the coin selector and the USB interface?

Thanks for your help

[Steveearle86]

Sorry to bump but can anyone help with my question re the 5v USB encoder above?