On 7/22/2014 7:04 PM, wrote:
OK, sorry for top-posting but a picture is worth a thousand words. BTW, thanks for helping with this.

Here is what's going on: https://www.flickr.com/photos/andrew...7645862229985/

1. Just a shot of the inside of the probe

2. No BNC connector, not probing anything: we're just getting noise

3. No BNC connector, the tip touched to the shield

4. No BNC connector, the ground clip (next to the tip) touched to the shield

5. No BNC connector, the tip touched to the square wave output. Here is what leads me to believe that the tip-to-center-conductor path is OK as it's making it all the way to the scope.

6. But...as soon as I connect the tip AND the ground clip to the square wave output + earth, the signal goes to 0V.

7. Now the BNC connector goes on, the probe is not probing anything, and we have a solid 0V (no noise)

8. The BNC connector is still on, the probe tip is on the square wave output: still 0V

9. The BNC connector is still on, the probe tip and ground clip are on the square wave output+earth: still 0V

10. Just for illustration, a different known-good working probe shows the expected result.



Ok, I'm not familiar with that probe, But when you put the BNC
connector back on, do you measure low ohms from the BNC to the other end
of the compensation housing?
Since you have it apart can you measure the cable shield from end to end?
Is it continuous?
Do you think the cable shield makes a good connection to the
compensation housing when you put it together?

You have a funny wire making your ground in the next to the last
picture, what's that about?
Can you post a picture of that end of your probe?
Why not the normal wire with an alligator clip?

I don't think I've helped yet, but gave you some items to check.

Mikek