[sdiy] broken oberheim matrix 6r

[Bob Weigel]

Firstly, I'm trying to update *that* page as we speak where I detail the 
types of chips or technologies that are used for the various aspects of 
each synth.  The matrix 6 you'll see though from the general page for 
that unit on the www.imt.net/~sounddoctorin/synthtec link... The 
oscillators are digital.  THe 3396 isn't the voice on a chip that has a 
vco. It's got waveform converters designed to be driven by a chip LIKE 
the 8253 which is used in the Kawai DCO synths, some Rolands like MKS30, 
and others.  Those are the oscillators driven by entirely digital stuff 
of course.
Anyway the 3396 also has a mixer, VCF and a VCA which can take a 
waveform converter and FM the VCF with it and two other vca's for eg mod 
and dynamics. The converters are nice with all the options you'd expect 
from Doug at that time :-). 

Ok anyway..so bottom line, if no output it's not those chips anyway 
likely since they don't normally all fail at once.  And I doubt there's 
a possibility of an offset taking out everything.  Usually they put 
enough impedence on the outs so that an offset only takes out the voice 
effected totally.

You checked all supply voltages with a scope right?  You might have bad 
regulation..THe outs are current outputs so you likely won't see much 
signal there.  They drive a current to voltage converter amp at some 
point.  I don't have schemos handy.

But anyway that hopefully helps some -Bob

Danjel van Tijn wrote:

> Hi karl,
>
> Does the 8253 timer commonly fail? I will definitely check it out...
>
> thanks for the tip!
>
> Danjel
>
> On 4/4/07, karl dalen <dalenkarl at yahoo.se> wrote:
>
>> Have you checked the 8253 timer?
>>
>> If these dont work you wont get any sound!
>>
>> KD
>>
>>  for the  os
>> --- Danjel van Tijn <syntheticdan at gmail.com> skrev:
>>
>> > Hi Guys,
>> >
>> > I tried to send this out a while ago but the list was onbiously down.
>> > I recently took a gamble to buy a broken Oberheim matrix 6r.
>> > The unit turns on, receives midi but no sound out. I thought it might
>> > be a problem with corrupt memory data but no amounts of resets or self
>> > callibration have worked (nor has re-programming voices from a PC).
>> > When I run callibration I get the following errors:
>> > Bad Wave 63
>> > Bad Res 63
>> > Bad VcF 63
>> > which basically means that all the voice chips are failing the 
>> callibration.
>> >
>> > I have tried re-seating all connectors, cleaning the pins of the
>> > cem3396 chips (in case of oxidation), I checked all power rails and
>> > have tried to trace through signals with a scope.
>> > It looks like the CEM3396 chips are receiving the appropriae
>> > corresponding signal changes (e.g. if I edit a parameter I see changes
>> > at the inputs of a voice chip). However, the refference signal to the
>> > chip is very very low amplitude and saw haped. Also I get no audio out
>> > of the voice chips.
>> >
>> > What are the chances that all 6 voice chips spontaneously died? I have
>> > ordered a sigle replacement chip to see if that makes a difference for
>> > a single voice.
>> >
>> > Any other clues as to what may be wrong???
>> >
>> > thanks!
>> > Danjel
>> >
>> > --
>> > www.intellijel.com
>> > www.myspace.com/intellijel
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>>
>>
>>
>>
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