Re: Matrix-1000 filter issue

Which chip is in question? The 74HC32? The two 4051's are your demuxer's. If
the chip that should be the 74HC32 is different, then yes, it needs to be
replaced with a 74HC32. Especially if it is a NTE/ECG type replacement part.
If it happens to be a different make of a 74HC32 then you have an
interesting dilemma. Did someone replace the chip, got it sort of working,
and then passed it off as a completed repair? Then you need to start
troubleshooting at the individual component level.

I don't really see too many Matrix 6/1000's in for repair since issues like
this can quickly take the repair into the realm of "approaching the value of
the instrument".

Wes Taggart
Analogics
http://www.analogics.org/

"Tom Waters" <tstimac02@xxxxxxxxxxxxxxx> wrote in message
news:dih9sh$cj8$1@xxxxxxxxxxxxxxxxx
> "Wes" <flattopnospam@xxxxxxxxxxxx> wrote in message:
> > Yes, I was worried about the diagnosis. Have you actually done all the
> > hidden function calibration through the front panel menu? If so, and you
>
> I did "hard reset" (with Enter key while Powering on) and "Calibrate". But
> no help.
>
> > still have issues, then I think you are dealing with a support part
> > problem
> > in the voice and that will need the services of a tech.
>
> Well, actually i am a tech. I was just hoping someone has the service
manual
> cause i never repaired Matrix. Anyway i noticed one interesting thing.
This
> 6-th voice that is making filter issue is having one of the chips
different.
> It is not Toshiba like on other 5 voices. Maybe this is where the trick
is.
> It is one of those two multiplexer chips that actually take controll of
the
> CEM. I suppose one of them is giving a different cutoff value, now
measured
> to be 8 points below others.
>
> I also tried "swap trick" where i swapped CEM of the 6-th voice with the
> 5-th. Same issue. At least that shows CEM's are all right.
>
>


.

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