Fluke pod cables (related to 6502 pod)

Working on a set of Cloak & Dagger boards I found that my one good set just didn't reliably want to pass self test or run with the pod connected.

Talking to Kev I started thinking maybe the pod was a touch slow or that the standard flat ribbon cable was giving too much cross talk.

I pulled a twisted pair pod cable off of a spare 8085 pod and set it up for self test. Everything works fine UNLESS I actually connect the shield ground connector on the cable to the pod ground screw. Did some pin checks and it appears they connect the shield ground directly to pin 20 (GND) in the UUT end of the cable. Reasonable.

The reason the 6502 pod fails if I connect the shield is that on CPU pin 20 is AB11 and the CPU ground is on pin 21 for the 6502.

Leaving the shield ground unconnected the C&D board comes up and passes self test. So I do think there is cross talk going in the flat cable.

Did anyone ever find a solid lead on replacement pod cables?

Oh I also looked at a spare Z80 pod which has a nice juicy 18" or so twisted pair pod cable. Its got shield ground connected to pin 29 and something else around pin 25 that I haven't figured out yet as even with the shield unconnected the pod won't pass self test.

David

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Received on Thu Feb 19 03:12:36 2004