From: "Craig Aker"
Subject: Re: Tron - Huh?  My attract mode now has sound????
Date: Thu, 1 Mar 2001 20:11:19 -0600


>So, for those of us that want sound during the attract mode -- what is
>the best method to 'disable' the muting circuit?

Remove R135.

I would only recommend this for tron, as some mcr2's have no sound during
attract, while others have sound that can get stuck and begin looping, which
is not a pleasant experience.  For those of you interested in the whole
story, here is my explaination from an earlier email:

The attract noise is not supposed to be there, and I don't think there
is a setup option to turn it on.  There is a mute circuit that is controlled
by one of the 8910 sound chips. This is typically located on the top board
of the 3 board sandwich.  If it is loose in its socket you could get sound,
or any one of the chips down the line could be loose or faulty.  If this
just happened with a move, probably something has come loose.  If not you
probably have one of those 3 chips bad (or something shorted out in this
path).  Refer to the schematic (check wiretap, any mcr2 schematic will do)
and you can follow the mute line from the 8910(F6 pin 6) to the 7404(A1) and
finally to the 3900(D3).  If you have a voltmeter you can trace this line
and see where the problem is.  I have seen a few tron boards that sound a
little different in regard to the audio quality, but all have had the mute
circuit functioning.  What I've found that is more squirrley is the
mute/volume/stereo handling circuit involving the 3900 current amplifier.
(btw don't damage the 3900 or the 8910, I don't know of a suitable
replacement for these).


craig