MMJ Info

From: Jerome Fine <jhfine_at_idirect.com>
Date: Sat Oct 21 21:45:41 2000

>William Fulmor 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):

Jerome Fine replies:

I appreciate the suggestion made below, however, I believe that I
have located someone with some RJ11 blanks and a press. ASAP,
I will cut the current cable I have to test my concept. If that works,
I will not need to file anything - plus the connections should be as
stable and firm as with DEC hardware. Otherwise, I will try out
your method. Thank you.

> 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.

I think that the most satisfying part of the procedure is being able to
defeat the DECism. Seems like you enjoyed it as well.

Sincerely yours,

Jerome Fine
Received on Sat Oct 21 2000 - 21:45:41 BST