ASM1 wireing

[Stopp,Gene]

Well you know this actually is a pretty good question. Admittedly in my
ASM-1 documentation I only give minor reference to panel pot wiring
suggestions, showing only one example of each type of connection
(voltage divider, attenuator, etc.). So here's an attempt at a more
detailed description:

Once the circuit board is completed, the panel should be assembled and
wired. What I do for panel wiring is to take the assembled panel and lay
it down face-down on the bench. Then I proceed to connect all power
points together, from part to part. Then I add wires for signals that go
from jacks to pots. In all of these cases, I usually use 22- or 24-gauge
insulated solid wire (these days I use Cat-4 or Cat-5 UTP conductors, to
be specific, just because I have so much laying around). Solid wire is
good for panels, because you can bend it into straights and bends like
plumbing. It has no physical stress on it, and if it's solid you can put
it into place out of the way and it will stay there. If the panel is not
bare metal on the backside, all the ground points need to be connected
together also. I usually use the same wire for this, except that the
insulation is completely removed so that it's just bare copper running
from point to point. This way I can solder new ground connections
anywhere along the runs, creating a "web" of ground wires. Rather than
just running a single wire from the start to the finish, snaking all
around the parts, I interconnect the ground points from different
sections in a mesh all over the place so that return current can flow
freely everywhere. I do this even with aluminum panels - I know that
aluminum oxide coats any aluminum that is exposed to air, and it's an
insulator (albeit easily penetrated), so to eliminate any chance of a
high-impedance ground I do this just to be safe.

When I am finished, I have a two completed assemblies - one is the
circuit board, one is the panel. I then mount these assemblies into the
enclosure, and proceed to wire each point on the PCB to its proper place
on the panel. For this I usually use 22- or 24- gauge stranded wire. I
have found that a great source for this kind of wire in quantity is
ribbon cable. I just get a nice length and peel off what I need.
Multi-color is good for this because it helps keep track of which wire
is which by color. You can even keep the wires grouped in twos or threes
for some kinds of signals - for example, when you run wires to a VCO
frequency input structure, you can group together the fine tune, course
tune, 1v/oct, and other related wires with no danger of crosstalk. One
thing that you want to avoid when using ribbon cable is running audio
together from different sections, or audio with CV's, or gate signals
with either CV's or audio.

I never use coax for "standard" synthesizer signals. There is really no
need  - what you are trying to block out with coax is external
influences on small-level audio, and everything in a synthesizer is of
such a high level that it will swamp out any EMI. Also, the synthesizer
signal sources are usually of such high drive/low impedance that they
will prevent any substantial noise pickup. Just remember to keep the
wires from being *exactly* parellel for any distance (such as in the
ribbon cable case). This is a little too much coupling. You can use coax
for situations when you are bringing in or out a line level signal to
the outside world, like a microphone input or the final audio output.
Some people may disagree with me here and use a lot of coax for
waveforms and audio, but I never see any crosstalk problems with simple
stranded wires, for my purposes.

For power,  I wire the PCB to the power supply with much larger wire -
usually 14- or 18- gauge stranded insulated wire. I wire the panel to
the power supply with the same heavy wire. Now notice that both the
panel and the PCB have rugged, low-impedance connections to the power
supply, and there is a low-impedance ground path between the panel and
the PCB through these heavy wires through the power supply 0v terminal.

Hope this helps,

 - Gene
 ----------
From: Gur Milstein
To: synth-diy
Subject: ASM1 wireing
Date: Thursday, June 04, 1998 6:21PM

hi DIY.
can some of you ASM1 builders please write an exhaustive
discreptiuon on how to wire the ASM1.
1)whats importent ?
2)which wires should be coax (if any) ?
3)frome which pot start wireing the +/- ?
4)should pot GND be conected to the jack GND ?
5)can wires be long,how long ?
6)size (thic/thin) of wires recomended for +/- GND and
cv signals ?
7)divergence of wires ?
8)wires frome power supply to +/- GND ?

it seems that my ASM1 pcb is well asembeld but
the wireing makes me lots of problem,its the only
thing that ther are no info about in Gene's doc .
(hi Gene add to the doc a little draw about it)

it is simple but not to everybody !

thanx
Gur Milstein