[sdiy] SCI Six-Trak

Bob Weigel sounddoctorin at imt.net
Mon Nov 3 11:23:40 CET 2008


Yes that's correct it does count through the voices as it autotunes on 
boot.  It also retunes them automatically every 30 minutes I think of 
idle time.  Making a bit of a bump in the mix!  Bad idea.  They should 
have made that a toggleable feature.

Anyway yeah it's probably got a bad voice chip.  I haven't seen that 
happen on them but imagine that would be correct.  -Bob

Steve Lenham wrote:

> ----- Original Message ----- From: "mark verbos" <mverbos at earthlink.net>
>
>> Does anyone know what the story with revisions of this is? I have  
>> fixed 3 of them that all had green PCBs and matched the schematic I  
>> downloaded. The one I'm looking at now has a blue PCB and a bunch of  
>> green wires modding it on the solder side. It has no U123 installed.
>
>
> I think what you have there is a Rev.A board. I have one too; most of 
> the same ICs are present but, as you found, they are all numbered 
> differently. I haven't seen a schematic for the Rev.A. It just makes 
> faultfinding more fun - mine had a stuck bit on the DAC which made it 
> behave very strangely.
>
> IIRC, the Rev.A uses the reviled MM5xxx noise generator IC rather than 
> the noise transistor found in later Revs. According to NoteIt 
> (http://www.geocities.com/SoHo/2163/sc.html), serial numbers up to 900 
> were Rev.As.
>
>> There's just a "3" on the screen all the time.
>
>
> I think the Sixtrak autotunes at power-up and counts through the six 
> voices, so that might indicate a problem with voice 3. Does swapping 
> CEM3394s in the voices change the number?
>
>> It could be the EPROM, but I don't have a schemtic that matches and  
>> now I'm lost.
>
>
> If you decide to replace/reprogram the EPROM, be aware that the Rev.A 
> requires an earlier version of the firmware (v0.9), not the latest. It 
> can be downloaded from NoteIt's site as above.
>
>> Anyone?
>
>
> Yes, me. Hope it helps!
>
> Cheers,
>
> Steve L.
>
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