[sdiy] CA3046 Heater / Substrate Question

Michael E Caloroso mec.forumreader at gmail.com
Fri May 6 03:51:40 CEST 2016


Beware of Prodigy service manuals on the net.  There were two versions
of Prodigy synths and the designators have changed.  I have seen
online manuals where the text referred to designators of one version,
while the embedded schematic in the PDF is the other one.

MC

On 5/5/16, Nils Pipenbrinck <n.pipenbrinck at hilbert-space.de> wrote:
> On 05/05/2016 09:40 PM, Nils Pipenbrinck wrote:
>>
>> I doubt this is the reason. I replaced Q2 by a non-array transistor
>> (2N3904) and all the strange behaviour just goes away.
>>
>> Obviously the isolated Q2 doesn't help the heating, but the electrical
>> difference between the array transistor and the 2N3904 that I've used is
>> the common substrate. Not much more.
>
> Argh! Q3, not Q2.
>
>
> Btw, since the expo-converter is not directly influencing the heater I
> can for now just fake and use one side of the transistor pair for
> heating. That way I'll at least be able to find out how much difference
> it would make. If it's worth it I'll find a way to make it work.
>
> Best,
> Nils
>
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