This circuit is designed to take un-amplified stereo audio from the PC's sound card and produce either mono or stereo amplified output required by the JAMMA cabinet speaker(s).  SK5 is a 3.5mm stereo jack socket and should be connected to the PC soundcards un-amplified output jack.  PL3 provides an alternative audio in connection.

Standard Mono JAMMA output appears on the JAMMA loom PCB edge connector pins 10 (spk+) and L (spk-).  A second speaker connection is provided, if required, by linking jumpers LK4 and LK5 to the JAMMA loom PCB edge connector pins 11 and M to produce stereo.

This circuit is powered by the +12V supply from the JAMMA loom.

Mixer Circuit

Because some games have stereo sound and standard JAMMA uses mono, it is necessary to mix the stereo to make mono.  This is done with IC8a, R20, R21 and R18.  To mix the stereo into mono position the connect the jumper, LK7, on pins 1 and 2.

If you have a JAMMA cabinet which is wired with 2 speakers for stereo, i.e. your JAMMA loom uses pins 11 & M as additional audio connections, then set jumper LK7 to pins 2 and 3.  This will give you stereo output.

Amplifier

This circuit was taken directly from the Kitsrus web site;  Check out Kit97 for a full description of how it works.

Copyright 2000/2001.
You can email me at: ZangTumbTumb@freeUK.com.
Last updated: August 23, 2001.