[sdiy] Early Ensoniq Mirage DSK-8 schematics

[Rutger Vlek]

Hi Gordon,

Thanks, yea I already swapped out the 4051 for a new one. No luck. The problem happens much earlier. It sound like it's multiplexing the voices correctly, just very softly, and with a lof of noise. I'm suspecting the feedback loop around the DOC for the volume regulation.

@Sarah: indeed the system is impressive! Somehow it looks elegantly simple, yet uses rather complex tricks! Lovely design, though a little more prone to failure than some synths.

Rutger

On 10 sep 2016, at 00:39, Gordonjcp wrote:

> On Fri, Sep 09, 2016 at 05:00:49PM +0200, Rutger Vlek wrote:
>> Hi guys,
>> 
>> does anyone have schematics for the early Mirage DSK-8? I'm struggling with a sound generation problem. Basically, I'm not getting any from the voice mux (4051), before the CEMs. I swapped out the DOC chip for a 'new' one, but no luck.
>> 
>> I found a schematic dated 10-17-1985, but that seems different from the DSK-8 I'm looking at. It has a -8V rather than a -12V supply line. And it has double the amount of LM318 opamps for the conversion of the DOC chips DAC output (+sig and -sig), and double the LM318s for the volume feedback circuit from and to the DOC IC.
> 
> I do, somewhere.  I'll have a rake about tomorrow morning.
> 
> DOC chips rarely fail.  Have you swapped out the 4051?  That's a very likely failure.
> 
> -- 
> Gordonjcp MM0YEQ
> 
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