I have a device that I need to reverse-engineer. This device has a large multi-conductor cable -- over 20 wires that are jacketed into two circular bundles. I'll need to look at all these signals with an oscilloscope. (Note that I have no need to disconnect and reconnect individual wires, I just need to look at those signals.)

I know of a couple of not-so-easy ways to do this. I could strip off a bit of insulation on all 20 wires (and hope I don't short those bare parts together when I'm shuffling the wires around). Or I could completely sever the cable, get some perf-board, and assemble a short perf-board intersection that takes all 20 wires, puts a jumper in series, and then resumes the cable run.

Is there any easier way to do this? Are there any off-the-shelf items out there to make it easier to probe a whole bunch of wires without issues? Or is there any easier way to do this by hand...?

  • \$\begingroup\$ Get some insulation piercing probes. \$\endgroup\$ – DKNguyen Jul 2 '19 at 0:14
  • \$\begingroup\$ Yes needles work well for stranded wires. \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jul 2 '19 at 3:37
  • \$\begingroup\$ Is there a connector at either end of the cable? \$\endgroup\$ – david Jul 2 '19 at 7:26
  • \$\begingroup\$ Thanks @DKNguyen, that looks like a good idea. \$\endgroup\$ – Mr. Snrub Jul 2 '19 at 7:31
  • \$\begingroup\$ @david Yes, at one end, but there is no exposed copper on the connector so I still have the same problem. And it's a weird round connector, so not like I can get one of those easy 25-pin DIN breakout boxes or anything like that. \$\endgroup\$ – Mr. Snrub Jul 2 '19 at 7:31

do these wires have a termination? you have some other options one of your comments in your posts mentions piercing probes, depending on your cables this could be and option... used in cars often.

I don't know how it is connected, because it helps to decide what is best, I think you should look up back-probing and piercing and see if any of those is worth the risk versus making a termination for all 20 wires yourself.

this video has a simple explanation

  • \$\begingroup\$ Nope, the wires in question are part of a fully-jacketed cable. Long story short, the only sensible way I can see to access these signals is to cut the cable open somehow. There is no exposed copper at all, but the piercing needles are prob a good idea. \$\endgroup\$ – Mr. Snrub Jul 2 '19 at 6:20

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