...
BTW, it looks the 9 ohm measurement on my board was the connection from the left 'B' to the middle 'B'. I had 0 ohms from the middle 'B' to the right 'B'. Weird...
You could get more precise with a finger poke by using, say, a 1k resistor connected to a fine probe to pull up or pull down various pins on the zoom chips to see exactly which pin(s) is being sensitive. The zoom chip appears to be a 3.3V part, or at least the bus interface is, so a pullup to 3.3V would be appropriate.
U91 (all sections) and U92 (pins 1, 2, 3) are 2 input ANDs, and one input of each section is connected to pin 29 on the U29 Altera FLEX. The output of the 5 ANDs are each connected to one of the 5 zoom chips. In addition, one databus trace is connected to the other side of each of the the ANDs.
So, the selection mechanism might be some kind of latched select depending on which databus trace is TRUE at the time. Perhaps it's valid to select multiple zoom chips at the same time for some operations. I didn't analyze it on a running system.
Without getting too crazy tracing everything at the moment, I would add to my suggestion to also poke the 1k at U91 and U92. Sections [4,5,6] [10,9,8] and [13,12,11] of U92 appear to be unused and are left floating (which design-wise is not a good idea).
One added word of caution... I've managed to kill chips on these boards with sloppy probing by dragging a probe from one pin to the next, essentially shorting two adjacent pins together. A couple of comparators met their demise because of this, but it could happen to any chip.
pv> x zoomChipSelTest
Slot E: Filling FISOs for Pods #1 with zeroes...
Slot E: Checking FISO #4...
Slot E: Checking FISO #3...
Slot E: Checking FISO #2...
Slot E: Checking FISO #1...
Slot E: Checking FISO #0...
Slot E: Filling FISOs for Pods #2 with zeroes...
Slot E: Checking FISO #4...
Slot E: Checking FISO #3...
Slot E: Checking FISO #2...
Slot E: Checking FISO #1...
Slot E: Checking FISO #0...
Slot E: Filling FISOs for Pods #3 with zeroes...
Slot E: Checking FISO #4...
Slot E: Checking FISO #3...
Slot E: Checking FISO #2...
Slot E: Checking FISO #1...
Slot E: Checking FISO #0...
Slot E: Filling FISOs for Pods #4 with zeroes...
Slot E: Checking FISO #4...
Slot E: Checking FISO #3...
Slot E: Checking FISO #2...
Slot E: Checking FISO #1...
Slot E: Checking FISO #0...
Mod E: TEST passed # "zoomChipSelTest" (13, 5, 1)
pv> x zoomAcqTest
Slot E: Chip9: edgeCount=2570, exp=811
> Slot E: Chip9: Zoom Acquisition Data Frequency Test Failed!
Slot E: Chip8: edgeCount=2570, exp=811
> Slot E: Chip8: Zoom Acquisition Data Frequency Test Failed!
Mod E: TEST FAILED # "zoomAcqTest" (7, 7, -1)
#!/bin/sh
export PVRESULTLEVEL=10
export PVDEBUGLEVEL=9
(
sleep 8
echo "s e"
while true; do
echo "x zoomChipSelTest"
sleep 3
done
) | pv
I can confirm it's 1GHz.
I can confirm it's 1GHz.Haha... gotta rub it in with a screenshot from your awesome scope!
DogP