This is a PCB based on an article in one of the Fluke magazines that explained how to make adapters to allow testing of boards based on processors for which Fluke pods were not available. The article takes a pod that has similar characteristics to the CPU required, and explains about converting the signals, and conveniently (for me), it ended with the full wiring for an S2650 adapter. (Get the original article here)
However, making one that would be compact enough to be usable and not have a mass of wires required a PCB, so here is my attempt at such a PCB. The picture shows the adapter in use on ‘The Invaders’ PCB.
This shows the top of the board. visible are the logic chips used to do the necessary combination and other changes to control lines, and the socket where the Z80 fluke plugs in. To make it more robust for continued use, I will probably fit a 40 pin ZIF socket into this socket at some point.
The side view shows the 40 pins and socket fitted to the other CPU slot. This is the connector that is plugged into the UUT, so again, I usually double up on sockets so if a pin gets damaged, then I can just replace that socket. (I also do this on the actual Fluke pods – it can save a lot of grief)
Also, just visible in the picture are the smoothing caps fitted underneath each TTL used, not sure if these are strictly necessary, but I had some handy so I put them on.
You can download the Gerber files here and get your own made up (no warranty – but it worked for me)
The parts you will need to populate the board with are as follows :-
- U1 = 74LS00
- U2 = 74S00
- U3 = 74LS02
- U4 = 74LS11
- E$2 = 330 ohm
- E$3 = 1k ohm
- Ceramic cap near E$2 = 300pf
- Smoothing Caps
- 40 pin sockets
- PCB Pins