Scope switches to GND when touching the case -> J3

[r0ck]

Hi,

I have an issue that the Scope shorts somewhere to GND which makes it change between DC and GND rapidly, when in use.
This can be reproduced when gently applying pressure to the case. Also my case is under pressure since the frontplate came bent and not straight.

Finally found the reason for this. The unused J3 connector that is used when calibrating the scope for the first time, is pushing against the mainboard. It even scratched some traces open which is why it can make contact and shorts out.

My suggestion is to unsolder it or I will try to insulate the area with some tape. But if you have these symptoms and you dont do anything about it, you might damage the mainboard even more.

[r0ck]

desoldering was a little mess.

The testsignal is not constant it moves right or left . Anyone any ideas what might have caused this?

[qu1ck]

The testsignal is not constant it moves right or left . Anyone any ideas what might have caused this?

Adjust your trigger point (pink marker on the right of the screen). You can autocenter it on the signal average by long pressing the trigger button (or sec/div button, can't remember which).

[r0ck]

already did that.

What I mean is that the test signal is nervous. it jumps left and right. not up and down.

[qu1ck]

Can you post a screenshot?

[r0ck]

Sorry for the late response. The Device died after I removed J3. Replaced the Diode which died, but didnt help.

However the reason I post this is because I saw the new Revision Boards and change notes. As I see you removed the J3 connector completely that was making trouble for me along with trimmer design changes. Thank you for listening to feedback and implement it in new revisions !

[MorganFlint]

Just in case anyone has the same problem: To prevent J3 from touching the digital board, I put some kapton tape on it in the zone where it could make contact (any plastic isolating tape would do the job).

[r0ck]

Just in case anyone has the same problem: To prevent J3 from touching the digital board, I put some kapton tape on it in the zone where it could make contact (any plastic isolating tape would do the job).

That was also my first attempt. However the problem was that there is a huge variation in building quality, especially regarding the outer shell.
Which means when you assemble the scope, there might be tensions because of the non perfect case parts.

That presses down the J3 Pins on the mainboard and scratches on it, even if you dont press yourself. And when I put insulation tape on the board it made the board thicker and thus you get even more tension. It might be temporary solution that there is no contact but the pressure gets even more and is no guaranteed fix . Kinda makes the problem worse.

If you have the space it might be an adequate fix. But that wasnt the case for me.

[johng]

An alternative to tape is to cut approx. 1mm length off the pins.
This has the added benefit of making it easier to fit board and case together.
Credit for the idea goes to "Teledog", in a DSO Shell review on Amazon.ca (Shell sold by NooElec).