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Repair: Oberheim Matrix 6 / 6r /1000
SO, any of you got a Matrix 6? A 6r will do.. And to a lesser extent, but the same problems, a Matrix 1000? I do.. Got it in 1990 from a repair shop that could not fix it.. It was rusted and abused, so i had to bypass the volume slider years ago.. But, it always had the MAD SYNTH problem.. That is: the machine would crash randomly, and only a good beating and reset (power on holding down the STORE) would wake it up again.. So, after i got sick of it (1996?) i put it on blocks, sometimes checking to see how mad it was as the years went by.. Obviously, now, in 2008, the machine is 22 years old, and really desireable, so i decided to try and make it sane.
The Problems:
Random freezes, lockups etc. Lights on panel go out, screen fills with "@@@@@@@@@" etc..
Difficult to start the machine from cold.
Voice 6 Fails / sounds Different to the other voices, or acts up on some patches. Confirm WAVE ERROR (usually 63) - during the CALIBRATION, hold down the COMPARE button and a WAVE ERROR appears..
Note: If you remove the CEM chip for voice 6, and swap it with one of the others (easy to do on the 6 and 6r as the chips are in sockets), the fault IS THE SAME - this eliminates the hens-teeth CEM chip, and means something else in Voice 6 is iffey.
SO, first off, need to rebuild that PSU, so take it out and make a note of what all the capacitors are (picture 1) and what the regulators are, (1 x -12v, 1 x +12 v, 2 x 5v and 1 x -5) - order them up from RS or pester your local fusepusher.
I won't make a list here, because i know they used several different PSUs depending on where/when you were.. Probably.. Take a picture of the PSU before you start so you can check your work afterwards.. remember the Caps must go back in the way they were in the 1st place.. So, go ahead - Get those badboy Regs and Caps out of there and replaced with nice new ones. Remember the regulators have to be isolated from the plate they are bolted onto - so KEEP all the washers and plastic bits, you will need them.. Use solder wick/whatever to remove the parts, and clean up the excess solder, making sure you don't destroy the board like i did (picture 2) - but don't worry, it's bound to fall apart when you work on it - it is after all CRAP, so be prepared to make some jumps with the leads of the caps if need be (look closely at my mess..) Anyway, do it, and set aside all the bits you replaced to show your mates later (picture 3) and you are ready to put it back in the machine (picture 4) - CHECK THE CAPS ARE IN RIGHT!!! Stripes to - (minus) ok?
Hook it up and Reboot it. Don't worry if it appears to be dead at first, it isnt! keep switching it on & off and holding STORE and whatnot etc. Eventually it will behave, especially if you undo the ribbon connectors inside, then firmly reconnect them..
Do the Calibration a few times, is it happyier? Do you need to work on voice 6? you do? proceed then..
Now you can work on the voice board. (Picture 5)
SO, any of you got a Matrix 6? A 6r will do.. And to a lesser extent, but the same problems, a Matrix 1000? I do.. Got it in 1990 from a repair shop that could not fix it.. It was rusted and abused, so i had to bypass the volume slider years ago.. But, it always had the MAD SYNTH problem.. That is: the machine would crash randomly, and only a good beating and reset (power on holding down the STORE) would wake it up again.. So, after i got sick of it (1996?) i put it on blocks, sometimes checking to see how mad it was as the years went by.. Obviously, now, in 2008, the machine is 22 years old, and really desireable, so i decided to try and make it sane.
The Problems:
Random freezes, lockups etc. Lights on panel go out, screen fills with "@@@@@@@@@" etc..
Difficult to start the machine from cold.
Voice 6 Fails / sounds Different to the other voices, or acts up on some patches. Confirm WAVE ERROR (usually 63) - during the CALIBRATION, hold down the COMPARE button and a WAVE ERROR appears..
Note: If you remove the CEM chip for voice 6, and swap it with one of the others (easy to do on the 6 and 6r as the chips are in sockets), the fault IS THE SAME - this eliminates the hens-teeth CEM chip, and means something else in Voice 6 is iffey.
SO, first off, need to rebuild that PSU, so take it out and make a note of what all the capacitors are (picture 1) and what the regulators are, (1 x -12v, 1 x +12 v, 2 x 5v and 1 x -5) - order them up from RS or pester your local fusepusher.
I won't make a list here, because i know they used several different PSUs depending on where/when you were.. Probably.. Take a picture of the PSU before you start so you can check your work afterwards.. remember the Caps must go back in the way they were in the 1st place.. So, go ahead - Get those badboy Regs and Caps out of there and replaced with nice new ones. Remember the regulators have to be isolated from the plate they are bolted onto - so KEEP all the washers and plastic bits, you will need them.. Use solder wick/whatever to remove the parts, and clean up the excess solder, making sure you don't destroy the board like i did (picture 2) - but don't worry, it's bound to fall apart when you work on it - it is after all CRAP, so be prepared to make some jumps with the leads of the caps if need be (look closely at my mess..) Anyway, do it, and set aside all the bits you replaced to show your mates later (picture 3) and you are ready to put it back in the machine (picture 4) - CHECK THE CAPS ARE IN RIGHT!!! Stripes to - (minus) ok?
Hook it up and Reboot it. Don't worry if it appears to be dead at first, it isnt! keep switching it on & off and holding STORE and whatnot etc. Eventually it will behave, especially if you undo the ribbon connectors inside, then firmly reconnect them..
Do the Calibration a few times, is it happyier? Do you need to work on voice 6? you do? proceed then..
Now you can work on the voice board. (Picture 5)
2 calibrates should result in no fails, and a perfect working non-mad matrix synth!
NoT fOr ArMeR 
Not as bad as it used to be, but still, a little strange.. So i re-calibrated the HFOs as per the service manual's instructions, and decided the original ribbon cable was the culprit.. a Clue: when i leaned on the connector into the logic board, the machine froze! So after checking the tits out of the board, and doing a few cap replacements to cheer me up, i replaced the ribbon cable with an old 40-strand IDE cable, with plugs for 2 drives.. It's awkward, you cannot open the lid anymore fully - since the lead is spaced differently to the one that comes with the M6, but it is now solid. I mean really solid. Not, like, ALOT BETTER THEN IT USED TO BE solid, but really 12-hours of use with no pops and messing solid.
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