TPDD Rick Shear Cable

Note: This exact PCB and cable design are a bit obsolete now This page is just for reference.

This is Rick Shear's original PCB with everything else different to avoid some problems with Rick's first version:

Most DB25 backshells, including the standard grey one Rick used, don't actually fit into the opening around the rs232 port on the back of a Model 100. The plug is not able to be inserted all the way into the socket, even though it is just enough to make the connection usually. It's just weak and easily disconnected. This recipe has a special backshell that does fit all the way into the opening around the serial port on a Model 100.

Rick solved the problem of the 2x4 pin connector on the TPDD by finding an FB-100 cable and cutting it in half. This is not something many people can or should do. You can't by original FB-100 cables much easier than you can buy original TPDD cables. There are only rare old ones on ebay and you shouldn't destroy them. This recipe uses a "dupont" style connector for the TPDD end of the cable. A special one that has a polarity bump, but still all off-the-shelf new parts you just order from digkey or mouser or farnel or jameco or whoever.

There is also now a better version of the pcb. It's the same components and the same connections, just a smaller pcb with better routing.

You can use either PCB, and everything else is the same.

The numbers 1-7 on the PCB correspond to the numbers on the TPDD connector. Pin 8 on the TPDD is not used. Looking at the back of the TPDD drive, the pins are numbered like this:

7	5	3	1
8	6	4	2

You need a special crimp tool to crimp 28awg dupont style pins. Example: SN-28B Crimp Tool.
Additional materials:

3/16" heat shrink tubing

1/2" heat shrink tubing (double wall, 3:1 ratio)

The DB25 backshell is special. Most back shells don't fit in the opening in a Model 100. The back shell in the digikey cart above does.

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