I've been working with some ICXes and EPSes lately, and had to order more EPS cables.
I found out that there is apparently a second style of cable connector.
All the ones I've had so far use a clip similar to how an ATX motherboard power cable is retained and they have a soft rubber hood around it to hold the cable jacket weave to the cable end.
The ones I received have a hard plastic hood, and a thumb screw. none of my equipment has the mating threaded hole for the thumb screw. Additionally, one of the 10 pins is "filled in" on both ends of the new cables to prevent them being used on my gear.
What is so different about these two cables?
Is there any difference other than the attachment mechanism? (Ampacity, comms crossover?, thermal rating?) I've been comparing pinouts via DMM and haven't found a difference yet.
After EXHAUSTIVELY examining them with a continuity tester, I discovered this:
Both the old and new cables symmetrical and are wired "straight through". BUT, the new ones with the thumb screw have something very unique. There appears to be a Normally Open momentary switch build into the thumb screw, so that when the screw is not tightened down, it leaves one wire disconnected.
0 2 4 6 8 10 12 14 16 18
1 3 5 7 9 11 13 15 17 19
Holding the cable to look into the pins, using the above numbering, it is pin 11, which has these particular switches inline. And it may have a diode or resister inline under some heat shrink as well.
It looks to me like an ATX 'start signal', and probably, it's intended to make sure the two devices ground planes are electrically bonded before supplying DC power.
I suspect it is superfluous and can be wired out of the circuit to perform asthe old cable, but I would not have any mechanical means of retention.
Am I missing anything?