Fw: [sdiy] ETI vocoder input amps

[Hallvard Tangeraas]

At 19:47 +0100  09.11.01, >>>marjan<<< wrote:

>On the pcb you should move 47k pot one position to the right
>because you need it's wiper to 1458 pin 2, not as you drawn.
>There's one large pad empty all to the right, that's where
>you should move it.

This is getting more and more confusing! Apparently I'm even confusing
the corrected stuff with what I've done incorrectly in the past -I took
a look at the circuit again and compared it with the assembled PCB, and
I have indeed connected RV-2 like you explain here.
I've corrected the PCB layout picture and uploaded it again which now
shows (as far as I can see, if I haven't missed anything again) how my
actual PCB is set up. I've also slightly changed how the leftmost pin
of RV-1 is connected as that pin doesn't have a solder pad on the PCB
to connect to and could easily lead to confusion:

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


>Line input is OK but rather unusual design. I'd add another
>10k to ground from 4558's - pin.

But this isn't the reason why it's not functioning? It will just
improve the design, just like Jurgen Haible says in a previous message,
right?:

>>BTW, do yourself a favor add a resistor from the wiper of RV1
>>to GND. If the wiper temporarily looses contact, your inverting
>>line amp has no GND reference for that time. 33k would be good.


>I don't have more time right now but I'll take a more
>thourough look later,
>also, I don't get biegegreen and yellow dots

That's where the jack connectors go. The yellow on the left-hand side
for SK1, and the light-green on the right-hand side for SK2.
This is also pretty confusing as I've tried just about every
combination I can think of and still don't get it working.
After having figured out what's wrong with the actual circuit it's time
to look at exactly how the jacks are to be connected, using the
following diagram I've made of how the jacks work:

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


At this point I feel like throwing the whole vocoder out the window or
something. It's quite frustrating after having spent so many years of
work apparently for nothing (so far at least).


Hallvard
-- 
Notator/Creator SL : <http://www.notator.org>
Atari Launchpad    : <http://launchpad.atari.org>