Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!pt.cs.cmu.edu!andrew.cmu.edu!paul+
From: paul+@andrew.cmu.edu (Paul J. Dujmich)
Newsgroups: comp.sys.handhelds
Subject: Making an HP-48 Serial Cable
Message-ID: <8ah6Ivy00WBM41u0Vz@andrew.cmu.edu>
Date: 30 Jul 90 16:50:03 GMT
Organization: Computing Systems, Carnegie Mellon, Pittsburgh, PA
Lines: 68


The following procedure explains how to modify a .1 inch spacing Molex
connector for use on the HP-48 serial interface plug (2mm spacing).
CAUTION: Perform this procedure at your own risk. I am making this
information available for those who wish to make their own serial interface
cable, and I am not responsible for any damage you may experience in
implementing the following procedure.

1. Purchase a packet of .1 inch Molex terminal housings ( 4 circuit without
   locking ramp), part # 22-01-2041-P, from an electronics parts outlet of
   your choice. NEWARK ELECTRONICS, 200 Hightower Blvd, Pittsburgh, PA. 15205
   (412)788-1566   has them available in packs of 10 for aprox $2.55 under
   Newark part no 44F4522. You will also need terminals (the pins) and the
   part numbers for these are:  Molex # 08-50-0114  and Newark # 44F8234.
   They come in packages of 100 for $6.78. The total cost of about $10.00
   will give you enough parts to make 10 serial cables.

2. Before you insert the pins into the plastic connector housing, you will
   have to modify the plastic housing using one of the following two methods:

       Method 1: Take an ice pick, or any other sharp pointed object and
                 insert the tip into the small square holes on the connector
                 housing. Apply slight pressure while rotating the ice pick
                 and deform the square holes into larger round holes. Repeat
                 this procedure for each of the 4 square holes in the plastic
                 housing. After all 4 holes are rounded, try the connector
                 on the HP-48 plug (applying only very light pressure -- don't
                 force it). If the fit is still too snug, repeat the above
                 procedure again for each hole until the connector easily
                 slides onto the HP-48 Plug. Then, solder your cable wires
                 to the 4 Molex pins and insert the pins into the plastic
                 housing.

        Method 2: Rubthe plastic connector housing against a fine metal file
                  until you have removed the part of the housing that forms
                  the guide holes. File the housing down flat until you
                  can see the 4 plastic channels (compartments) inside.
                  Solder your cable wires to 4 Molex pins, and insert the
                  pins into the modified housing.


I have used both methods with good success. Method 1 is faster, but method 2
produces a connector that fits the HP-48 plug a little tighter.
The following diagram attempts to pinpoint the part of the plastic connector
that is modified. Both methods will produce a working connector that will
not bend or otherwise harm the HP-48 plug pins.

Again, if you try this, you do it at your own risk. One HP-48 Calculator
is all I ever intend to buy.

Have fun.
Paul


.1 inch plastic Molex housing
--------------------------------|
                                |          (Method 1)
                                | <------  ream this hole larger using
--------------------------------|          using an ice pick or other
                                |          sharp pointed pbject
                                |
--------------------------------|
                                |
                                |<----- (Method 2)
--------------------------------|        File this surface down aprox
                                |        1/16 of a inch untill the 4 channels
                                |        underneath are exposed
--------------------------------|