MMJ Info

From: William Fulmor <wpfulmor_at_dimensional.com>
Date: Fri Oct 20 00:12:03 2000

On Thu, 19 Oct 2000, Jerome Fine wrote:

[...]

> The
> key point is to attempt to become independent of the DEC "funny" offset
> within the first cable connected to the VT320. The annoying part is that
> I have a number of RJ11 to DB25 convertors without the "funny" DEC
> offset plus a small amount of 6 and 8 wire cable that I can't use since
> I first have to overcome the "funny" DEC offset.

The following took less than 15 minutes (testing included):

Using a utility knife or small diagonal wire cutters, cut the retainer
clip portion from an RJ11. Just cut the thin springy portion.

Look carefully at the remaining portion of the RJ11. Name the side with
the contacts the 'bottom'. You will see that the 'top' has a ridge of
plastic at the front edge protruding above the flat surface of the 'top'.
The ridge is perhaps 1/16 inch, or less, high.

Look at the opening of the MMJ, with the MMJ oriented with the contacts on
the 'bottom'. You will see that the plastic ridge on the RJ11 will
conflict with the 'ceiling' of the MMJ, but only for a length of
approximately 1/16 inch on the right-hand corner of the ridge.

Using a small, not too coarse file (in a pinch, a nail file would probably
work), file down approximately 1/16 inch of the right-hand coner of the
ridge on the RJ11. As your file approaches the body of of the RJ11,
switch to cut - and - fit mode.

When the RJ11 fits into the MMJ, stop filing.

I did this to an RJ11 crimped to a 6 conductor lead. I achieved a snug
fit which, while not locked in place, will probably stay mated to the
HB571-C into which it was inserted for any reasonable use. The HB571-C is
covered in a sort of rubberized plastic shell which might provide more
friction than a harder plastic on, say, a terminal.

I tested the continuity of the connections for each of the 6 conductors in
the lead. Each conductor mapped to one of pins 2,3,6, or 20 of the
HB571-C; two conductors mapped to pin 7 (assuming I counted the *&^%_at_#%
pins right). Factory prepared 6 conductor leads with crimped RJ11
connectors are available in almost any length with the conductors in
either 'rolled' or not 'rolled' configuration.

I have not tried to use this to connect any equipment.

YMMV, but it should be a cheap way to defeat this particular DECism.

Bill
Received on Fri Oct 20 2000 - 00:12:03 BST

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:33:17 BST