[sdiy] ETI vocoder input amps

[Hallvard Tangeraas]

At 14:35 +0200  25.10.01, jhaible at t-online.de wrote:


>> You haven't found the solution yet either? A real bummer
>> this circuit.
>
>In the schematics, the opamps are drawn wrong.
>Both, the second Mic amp stage (= first Line amp stage), and the
>EQ circuit (IC 2a) have the + and - inputs mixed up.
>
>The gain switching via TRS jack w/ 2 break contacts is
>a little adventurous, too, but it should work.

It's been a while, but I believe I looked over the circuit schematics
and noticed these errors as well, but also saw that the PCB itself was
OK.

I made a small web presentation as Magnus Danielson and I discussed
these problems off-list a while back, and I tried to "clean up" those
errors.
I've uploaded it again which shows how the components and wires are
connected to the PCB and the schematic as well, where I've labelled the
various pins of the ICs etc.

 http://home.c2i.net/w-392864/vocoder/new.html

 http://home.c2i.net/w-392864/vocoder/amp_schematic.gif (schematic)


I also have the German "Elrad" article of the same vocoder, and there's
a slight difference there. I've circled it in red:

  http://home.c2i.net/w-392864/vocoder/elrad_schematic.gif


As far as I can tell I've connected everything according the way it
should. Have I missed something obvious?


Hallvard
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