[sdiy] Looking for MATRIX 12 information

John Henson synthnerd at eircom.net
Wed May 30 23:35:59 CEST 2012

Hi everyone,
yesterday one of Ireland's only Matrix 12's arrived in for service.
Most of it is ok, but there is a PSU issue where the switch-mode 
frequency is audible for an hour
after switch on, I know it's supposed to be 30kHz, and it needs 
attention but for the time being the
voltages are of no major concern, all well within Spec.
I have the Xpander service guide but not the Matrix 12, so my question 
is probably a little silly!
The two 6 voice modules that sit one above the other, which card is 1-6 
and which is 7-12.
The two boards are different revisions, as this Matrix 12 is no. 9, the 
lower of the new boards is much
newer, and I would guess that at some point the whole 6 voice board was 
replaced, the engineering
change orders from the original Xpander are all implemented on the pcb 
of the newer module.
The problem I'm having is random tuning failures every time I tune, but 
voices 7-12 seem to be the
worst, failing more completely more often. The tuning comparator 
circuitry is very different between the
two boards, with a lot of components tack-soldered around the newer one.
Anyone out there have the service manual and/or the ECO's for the Matrix 12.

> Hi Mike !
> Until now, the only solution is this kit : http://www.lenham.clara.net/sound/market.html It is quite expensive since you have to replace the 3 displays. I'm not sure this kit is already available. I'm studying a similar product, but I'm not close to the solution ;-)
> Regards,
> Christophe
> Le 30 mai 2012 à 18:37, mike schmidt a écrit :
>> Thanks everyone for your suggestions! I ended up going with little diode in the uk, as suggested by christophe. part works great, and was pretty cheap to boot. Fwiw, it had a mid 90s date code.
>> I have one Final issue with the Matrix, The 20th character on the top right display is out. every segment in that character is out. Any ideas? Does anyone have a replacement for the florescent display? I've swapped the driver ics around, in hopes that the problem would follow, but alas, it didnt.
>> Thanks in advance!
>> -Mike
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