TPDD Rick Shear Cable: Difference between revisions

From Tandy Tech
Jump to navigation Jump to search
No edit summary
No edit summary
 
(4 intermediate revisions by the same user not shown)
Line 1: Line 1:
Note: There are two better options than this now. This is just for reference.
Note: This exact PCB and cable design are a bit obsolete now This page is just for reference.


This is the cable [https://www.arcadeshopper.com/wp/?page_id=11#!/Special-serial-cable-for-Tandy-Portable-Disk-Drive-and-Tandy-Portable-Disk-Drive-2/p/144969001/category=28313042 ArcadeShopper currently has for sale].
This is Rick Shear's original PCB with everything else different to avoid some problems with Rick's first version:


To build a cable based on Rick's original pcb, but using all standard parts that you can buy instead of having to find a FB100 cable and destroy it to get the special plug for the TPDD:
* 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.


:[https://oshpark.com/shared_projects/vntX40yC Rick's PCB]
* 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.
 
:[https://oshpark.com/shared_projects/vntX40yC Rick's original PCB] ( For the new PCB, see TPDD_Cable_PITA at https://github.com/bkw777/TPDD_Cable )
:[https://www.digikey.com/short/pmb339 Components]
:[https://www.digikey.com/short/pmb339 Components]


* The numbers 1-7 on the PCB correspond to the numbers on the TPDD connector in the diagram above. Pin 8 on the TPDD is not used.
* 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: [https://www.google.com/search?q=sn-28b SN-28B Crimp Tool].
* You need a special crimp tool to crimp 28awg dupont style pins. Example: [https://www.google.com/search?q=sn-28b SN-28B Crimp Tool].
* Additional materials:
* Additional materials:
:: 3/16" heat shrink tubing
:: 3/16" heat shrink tubing
:: 1/2" heat shrink tubing (double wall, 3:1 ratio)
:: 1/2" heat shrink tubing (double wall, 3:1 ratio)
* The pins on the db25 connector above will be too long for the solder pads on the pcb. You will need to cut them appoximately in half. Rick used a connector with solder cups instead of through-hole pins, because the solder cup style is what typically comes with typical back shells. But a standard 1.6mm thick pcb doesn't actually fit in betwen the rows of solder cups.
* 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.
* The back shell is special. Most back shells don't fit in the opening in a Model 100. The back shell in the digikey cart above does.


<gallery>
<gallery>

Latest revision as of 06:52, 31 July 2021

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.

Rick's original PCB ( For the new PCB, see TPDD_Cable_PITA at https://github.com/bkw777/TPDD_Cable )
Components
  • 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.