Hantek 6022BL repair

[Ario]

Hi all,

I have a hantek6022bl scope to fix. I am pretty sure that I need to replace a zener diode. The zener runs hot, and shorts out the usb power supply. My question is simple, I am I correct when I say that the zener in question is a 5.1V zener diode?
It is connected to a usb port.(please see my attached picture)

I am not 100% sure, and would like to hear someone's opinion. By the way would be the best way to identify it? It seems that there are no color code, or any other markings on the diode. I have ordered a bunch of zeners. they all look almost exactly the same, yet they are rated at different voltage values!

Any help would be appreciated!!

[Doctorandus_P]

It looks like it's relatively save to just remove the diode.
It seems to be connected to GND and the 5V input from USB, and it does indeed looks likely it's a 5V overvoltage protection device, but you should make sure before doing so. First draw a partial circuit of the components around it, and deduce it's real function from that.

It also looks like a design error. If it's a over voltage protection, I would put it behind the Polyfuse.

Does the diode measure as a regular diode in forward direction?
If it does not, it's likely kaput, but it could also be a bidirectional TVS.

[Ario]

@Doctorandus_P

Thanks for the reply. The zener is a dead short from either direction. It also gets super hot. So think I will replace it. I will update when done. The scope worked before, could it really be a design error after all this time?

regards

[Ario]

It works 
Thanks for the input!!!

Doctorandus_P