Diode Waveform Shaper wiring instructions, MOTM version

Posted 2/15/03 by John Loffink, updated 2/22/03

This page describes the Diode Waveform Shaper panel wiring.

I have decided not to use the headers but rather solder all wires directly to the board. Over a long period of time, the headers will just become a potential source of failure since the connections are not gas tight. It appears easiest to solder the wires to the PCB first, mount it to the bracket, then solder the wires to the panel mounted components. This requires knowing the lengths of the wires in advance, so these are listed below. You will want to twist the sets of wires together, except when otherwise indicated, for each component as they are soldered to the board, otherwise you will have a huge rats nest of wires.

I had yellow, blue and gray wire in stock. Just substitute whatever wire colors you have available. Use 22 gauge stranded wire. Wire connections should be soldered to the PCB before the PCB is mounted to the bracket. You then solder the connections to the panel components.

Unfortunately, only one PCB connection is provided for each of the positive and negative voltage references. Since chaining the connections on the pots can be somewhat difficult, we will instead use some unused summing op amp summing nodes on the PCB as a "multiple" for the reference connections.

If you do have the PCB mount type pots, remember to add a piece of shrink tubing over the wire before you solder it. Then you can shrink this over the exposed connection, which also strengthens it somewhat making the thin wires less prone to breakage.

On the twenty pin connectors P1-P4, the pin with square silk screening around it is pin 1. The pin opposite it is pin 2. So the one row is all odd numbered pins and the other row is all even numbered pins. The wire lengths given below are long enough to allow some slack in the wires so that they can be bundled and tied down near the apex of the front panel and the PCB bracket.

-10V Reference

+10V Reference

Limit switch, S1

Gain pot, R18

Offset pot, R17

Bkpt+1 pot, R3

Bkpt+2 pot, R7

Bkpt-1 pot, R1

Bkpt-2 pot, R5

Gain+1 pot, R4

Gain+2 pot, R8

Gain-1 pot, R2

Gain-2 pot, R6

In jack, J1

Mod+1 jack, J3

Mod+2 jack, J5

Mod-1 jack, J2

Mod-2 jack, J4

Out+1 jack

Out+2 jack

Out-1 jack

Out-2 jack

Out jack J10a (top)

Out jack J10b (bottom)

The individual OUT-+ stages are more complicated than your standard connections. Referring to the shaper_ sch.pdf, the basic idea is to take the outputs of the individual negative and positive waveform controls and bring them to the output (tip) of the jack through a 1K resistor. This connection is normalled to the right tab on the jacks. This is a normally closed connection to the ring connection, bottom tab. The ring connection then goes back to the 49.9K summing resistors (R2, R3, R9, R11) feeding U2B. This gives about a 2% gain error from the original design, but since this whole thing is nonlinear anyway I figure it doesn't matter. Here's a schematic of the basic idea.

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