Interested in a low-cost method of holding a scope probe securely against your PCB board? For this to work you’ll need a scope probe with a spring-loaded tip. I came up with this idea since the PS6000 series scope I was using from PicoScope comes with such probes. The end result looks like this:
Here’s a close-up of the PCB:
There’s some details in the YouTube movie:
Requires a simple magnetic base – the one I used is $15 from http://www.harborfreight.com/multipositional-magnetic-base-with-fine-adjustment-5645.html , if you’re in Canada then Princess Auto sells same thing, or Busy Bee (http://www.busybeetools.com/products/HOLDER-MAG-BASE-FINE-ADJ..html). If you have a metal desk the magnetic base will be super-handy, but even with a wood desk they are more than heavy enough to stay stationary.
I used a 3/8″ endmill to create the scope probe slot. The rod on the magnetic base is 10mm in diameter, and a 3/8″ drill is used to make a 9.5mm hole, which is then slotted to allow a good friction fit. The material I used was a block of Delrin that was about the right size to start with, and just had to cut down a little. You could use anything, even wood would work I think. Some sort of rubber coating (plastidip?) would also be nice I think, but it still worked fairly well.
You could probably make a nice 3D printed part instead of machining it out, as it’s fairly basic. This might allow you to get a better fit as well, for example matching the taper of the scope probe.
The only other thing to sort out is that the PCB moves around a little bit with the pressure on it. I’d suggest putting it on a rubber anti-static mat or something similar to hold it down as you probe it.
For this to work I think the spring-loaded tip is key, since it will keep pressure on the connection. You can see my other movie which shows how the spring-loaded tips work: