paul+@andrew.cmu.edu (Paul J. Dujmich) (07/30/90)
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 --------------------------------|
frechett@snoopy.Colorado.EDU (Mac the Ripper/ / / /) (07/31/90)
I have made a small setup that seems to work fine as is, and I have found how to modify it to fit nicely. This is quite simple. 1. find pins that will fit snugly by themselves to the hp48 pins. The pins that I refer to are small hollow brass pins that have a slight spring that applies pressure to anything inserted into it. 2. I used 5 strand flat wire and pulled off one of the strands. The flat wire helps hold the pins in the right order. (You can't get them in the wrong order) 3. Solder wire to pins, and then just shrink wrap everyother wire. The clearance is sooo tight that you can't do every one. You can stop here like I did for a while or you can make it better. 4. plug it into hp48. And drip a small amount of epoxy onto the pins where they attach to the wires and outside the calculator. Let it harden. Then pull it out and put more epoxy on it. Build it up to be bigger than the hole and just don't get it on the end. (epoxy does not stick to wax paper so is a good way to protect an area) Finally just file the block of epoxy to the shape of the hole. This will make a nice Totally indestructable pin casing for the hp end. I paid 5 dollars for my cable and am now happily running my modem with the 48 and dowloading stuff quite easily. ian frechett frechett@snoopy.colorado.edu