JAMMA Stereo mono question

[Uriah]

I am making a test rig for some JAMMA boards. I want to hook up a
stereo/mono speaker box so that I can test the sound on the boards.
So I have it wired up so that the when the switch is in the Mono
position it goes directly to the two JAMMA outputs L and 10 and when
the switch is in the Stereo position I use the Video ground and one
side L going to one of the speakers and the video ground and JAMMA 10
going to the other speaker. The questions I have are:

1. Can I use the Video ground for this kind of thing?
2. When the switch is in the stereo position I am reading 16Ohms
between JAMMA L&10. Is this normal? Or did I do something wrong.

I haven't turned it on with a board yet. I want to check with others
before I do this.

It is hard to describe the wiring without a diagram and I am not sure
if I can do that in Usenet. But, L is permanently wired to one of the
speakers. 10 is wired to a switch so that when it is in mono it just
goes straight to the speaker. When in Stereo 10 then goes directly to
the other speaker. Ground is wired so that when in Mono it is not in
the circuit at all but when in Stereo it goes the other side of 10 and
it also goes to the other pin on L through the switch. It is a Double
pole single throw kind of switch. I hope that is clear.

Thanks
Russ

[timh...@gmail.com]

Hi Russ,
Most likely using video ground is fine...but I am not sure if all
JAMMA PCBs take the video ground reference to actual ground or to a
ground level on its own special circuit. But most boards just use
regular ground as the video ground.

When you measure from pin 10 to pin L in your stereo mode, reading 16
ohms is what you should read...also measure from pin 10 to ground and
then pin L to ground in stereo mode...each reading should show 8 ohms.

Please keep in mind that most JAMMA PCBs that have a stereo output use
a different connector. The only two boards I know of that use stereo
with one speaker between pin 10 & ground and the other speaker between
pin L & ground is the Neo Geo MVS (Multi-slot) board pinout and the
1069-in-1 Multigame unit.

-Tim H.

[Ken Layton]

JAMMA stereo speakers are as follows:

Pin 10 (parts side) is left speaker +

Pin L (solder side) is left speaker -

Pin 11 (parts side) is right speaker +

Pin M (solder side) is right speaker -

JAMMA mono speaker is as follows:

Pin 10 (parts side) is speaker +

Pin L (solder side) is speaker -

The above connections are to go directly to a speaker. Do not mess
with any grounds.

[Russ]

Thank you very much for the help
Russ