On 7/22/2014 9:45 PM, wrote:
On Tuesday, July 22, 2014 10:21:02 PM UTC-4, amdx wrote:
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?

Not really. I've got 5 interesting points to measu

A: The probe tip, the thing you generally touch to points in a circuit
B: The probe ground clip, the wire next to the probe tip
C: The BNC center conductor, makes the connection to the scope
D: The BNC shield around the center conductor
E: The compensation housing

Now I believe B/D/E should really all be shorted to each other. This is confirmed with a DMM.

Now, for the other measurements:

A-B: 9Mohms
A-C: 9Mohms
A-D: 9Mohms
A-E: 9Mohms

B-C: 390 ohms

C-D: 390 ohms
C-E: 390 ohms

Since you have it apart can you measure the cable shield from end to end?

Is it continuous?

Yes, just about 0 ohms

Do you think the cable shield makes a good connection to the
compensation housing when you put it together?

Yes...see above measurements.

You have a funny wire making your ground in the next to the last
picture, what's that about?

That's the way the probe came (used...wish it had the retractable hood but it doesn't).

Can you post a picture of that end of your probe?
Why not the normal wire with an alligator clip?

Picture is he https://www.flickr.com/photos/andrew...57645862229985

I take what I can get! The probe came free with the scope (and to be fair, the seller told me the probe didn't work).

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

At least it helps to have someone to bounce ideas off of. This is really starting to stump me.




Mikek

Reading through your measurements, I don't notice anything wrong.
However, in your latest picture you don't have the BNC connector on
which completes the ground to the scope.
I noticed in your older pictures sometimes the BNC was on and
sometimes it was removed. It should always be on, because it completes
ground the from that funny wire near tip to the scope.
How about trying this.
Put the BNC back on.
Now measure from that funny wire at the tip (the ground), to the case of
the scope with a DVM. It should be 0 ohms.
Probably best to use the ground on the BNC for channel 2 to get a solid
ground. (No paint, not plastic, you know it is ground)
Mikek

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