[sdiy] Looking for MATRIX 12 information

jays at aracnet.com jays at aracnet.com
Thu May 31 01:35:37 CEST 2012

I've had a number of Obie Matrix units. All have had issues with chips
in sockets. Most of the time I've been able to 'fix' them by reseating
the chips and connectors. Except for the M6 keyboard which has the
boards facing downwards. In that case the processor fell out of the
socket and reinserting it fixed it. Be careful though. All my units had
leaf type pins in the chip sockets. If you aren't careful you can pull a
socket pin out or bend a chip lead.

I'd reseat the VCO and sample and hold chips and see what happens.

Good luck.
Jay S.

On Wed, 30 May 2012 22:35:59 +0100, John Henson <synthnerd at eircom.net>
> 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.
> Regards,
> John.
>> 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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