My Matrix 6 (keyboard version) had been in storage for several years. I finally had space in my house to set my gear up again and the first time I played my Matrix again it worked for about 90 seconds and then the same thing happened...no sound output, yet all MIDI functions and front panel display were operation and showing my patches. If I held the STORE button while powering up I could reset/calibrate the unit and sometimes get a default/initial patch to temporarily play. If I attempted to access any patches I'd lose all sound output. A restart/recalibrate might get it going, but sometimes it would show no display at all, like it was totally dead (without power).

To make a long story short, mine just needed a new CR2032 3V battery for the main motherboard, even though the one already in there still measured 3 volts. The battery is soldered in place, so care must be taken replacing it. Have a technician do it for you if you are not 100% comfortable with doing solder work. Once I replaced the battery it instantly came on (I used the STORE button calibrate procedure once again). The default patch came and sound came out. Due to the battery replacement all patches will have been lost and if you change to another patch your default patch will now be gone and you'll get no sound output whatsoever. In order to get the unit operational you have to either program and STORE new patches you create yourself or else load in some of the factory patches. Once you have patches saved the synth should survive a power cycle with no problem and behave like new again.

In order to load the patches I grabbed this zip file:

http://machines.hyperreal.org/manufacturers/Oberheim/Matrix-6-1000/patches/m6-factory.zip

from
http://machines.hyperreal.org/manufacturers/Oberheim/Matrix-6-1000/

I unzipped the MP3 files in it into a folder. I loaded a patch bank MP3 file into WinAmp media player as the current song (you could use iTunes, Windows Media Player...whatever). I took the headphone output from my PC, verified it was the active output, and patched it in the Matrix 6 "From Cassette" jack using a Mini-D to 1/4" adapter cable. Make sure the memory protect switch on the back of the Matrix is off. Select Master Edit #22, press the value button, start the file playing in your media player, then quickly select the YES button on the Matrix keypad. After a couple of minutes the patches from the file you selected should all be loaded and available for use.

Here is another explanation of the load/save feature, but still using tape, I believe:

http://www.kidnepro.com/KN/Oberheim/Oberheim-Matrix-6-Cassette-WAV-Loading-Instructions.html

Hopefully this works for you. A little investigation and soldering got me down to an under $10 repair instead of potentially hundreds if I had sent it to a repair shop. Hopefully my long explanation strikes a chord with others having problems with their old Matrix 6 keyboard or rack units and they are able to get theirs operational again also.

It was strange that the old battery had decent voltage and could retain the names of the patches but not the patches themselves. That's probably why it took me a while come to the conclusion that it was a battery problem and not some true audio issue. No patches, no sound!

Greg

--- In oberheim@yahoogroups.com , Aux <auxbla@...> wrote:
>
> Do you hear any noise at all Hiss, hum or whatsoever when it's connected to
> a mixer, leave the channel gain the way it is and open and close the main
> volume slider.
>
> My matrix 6 (keyboard) has the problem that it randomly sends MIDI messages
> (control change nr 4) with value 0 to my setup, which mutes the instruments
> that is selected in my sequencer at that moment. Check if your 6R sends out
> random MIDI messages with an application like MIDI monitor:
> http://www.snoize.com/MIDIMonitor
>
> Aux
>
> On Thu, Jun 2, 2011 at 11:48 PM, <atmospherics4@...> wrote:
>
> >
> >
> > Not stupid for me......I checked it.....not even headphone output.
> >
> > Sent via BlackBerry from T-Mobile
> > ------------------------------
> > *From: * Aux <auxbla@...>
> > *Sender: * oberheim@yahoogroups.com
> > *Date: *Thu, 2 Jun 2011 23:43:43 +0200
> > *To: *< oberheim@yahoogroups.com >
> > *ReplyTo: * oberheim@yahoogroups.com
> > *Subject: *[oberheim] Re: Matrix 6r down
> >
> >
> >
> > Maybe a stupid question, but have you checked the main volume
> >
> >
> >
>