[sdiy] Prophet 600 Syndrome ?

[Csaba Zvekan]

LOL. thanks Pete :)

So just go any preset turn the MIXER all the way to the right  
(Clockwise) we want to exclusively listen to OSC B's . And then try to  
play the last two octaves with frequency  set to 8 or even 10.  
Frequency on Oscillator B.
If it works I know I have a problem. Maybe the corresponding CEM3372  
is causing all that .I read something like that.

I greatly appreciate it

Csaba

On Jun 4, 2008, at 7:21 AM, Pete wrote:

> Honestly im pretty sure mine doesn't do what yours is doing, but im
> willing to help you out since I have a p600. How do you test each
> voice so I can try it?
>
> pete
>
> On Tue, Jun 3, 2008 at 1:35 PM, Csaba Zvekan <czvekan at gmail.com>  
> wrote:
>> Hi Synthpeople,
>>
>> After replacing various IC's, capacitors, CEM's I wonder if this  
>> what I am
>> encountering is maybe "normal" for the Prophet 600.
>>
>> When I tune the frequency higher than 6 on the OSCI B the Voice 3 B  
>> is not
>> playing in tune in the higher octaves.
>>
>>
>> So then I have replaced the following :
>>
>> 1. All tantalum capacitors to electrolyte capacitors with  the  
>> equivalent
>> value.
>>
>> 2. I replaced U416 the CMOS 4051 (even added a 0.1uF bypass  
>> capacitor)
>>
>> 3. Replaced all the 10nF capacitors
>> (C423,C422,C421,C424,C417,C418,C419,C420)
>>
>> 4. Replaced the CEM3340 (VOICE  3B)
>>
>> 5. Replaced the CEM3372(VOICE 3)
>>
>> 6. All the 0.1uF caps around the VOICE 3
>>
>> 7. And of course OP-AMP U423 with TL-082
>>
>>
>>
>> Still no Luck. I mean the synth performs and tunes very well except  
>> when you
>> tune OSC B in a very high pitch.
>> I slowly wonder if that is limitation of something in the DAC or  
>> somewhere
>> else. Since this is not making sense. All other voices play and  
>> scale fine
>> in high pitch but that Voice 3B.
>> Before I troubleshoot any further can somebody who has a PROPHET  
>> 600 confirm
>> that this a known bug or otherwise let me know that the OSC B  
>> scales and
>> plays fine in the higher octaves as well ?
>>
>>
>> Thanks
>>
>> Csaba
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>>
>
>
>
> -- 
> http://www.myspace.com/23isgood

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