Re: (ET) VDR-1

[Larry Chace <RLC1 etnainstruments com>]

Mike Finck asked about a wiring modification for the E20EC, described 
in a noticed from 18 June, 1973.

The list of known Elec-trak serial numbers has 4 enries for the 20EC, 
dated 21 June 1973, 22 June 1973, 28 June 1973, and 28 June 1973. 
The slightly earlier model, the E20EA, is dated 21 May 1973.  It is 
therefore likely that Mike's E20EC has the modification.

Looking at the little diode board, in the original wiring pattern, 
wire #49 connects directly to the common point for 4 diodes.  After 
the modification is installed, wire #49 connects to a (new) diode 
that connects to the common point.

In addition, wires #41 and 41.1 had connected to a diode.  With the 
modification that diode is deleted; #41 and 41.1 connect to the 
common point.

I think that the modification deals with the operator console white 
button for Cruise Control and Power Pulse.

Larry Chace, Ithaca, NY  I-5 and E15