Odd THC problem solved - ground between monitor and table frame

[holla2040]

I’ve had my Pro for about 3 years now, no THC problems until the last couple projects. I followed the troubleshooting guide and found ye old USB ground shorted to the frame problem. I’ve been using a mini PC without issue for 8 months, its power supply wall wart doesn’t have ground plug, it’s frame and shielding kind of float (required for the THC to function correctly). Checked Cut45 voltage output, divider voltage output, cables etc. All looks good. But 0.0V, for live test. While checking the resistance between USB shield and frame, I started unplugging cables. Found that my touchscreen HDMI caused the short. Huh? It’s worked for 8 months without an issue, now nothing.

Long story short, I made a super stiff monitor mount from a Dish TV antenna mount 8 months ago. With constant rotating, rubbed the paint off and this connected the monitor frame to the machine frame, shorting the HDMI shield to the frame and hence the mini PC USB shield to the frame, killing the THC voltage. I hope this makes sense.

I’ll figure out an isolation fix this weekend and get back to work.

[ds690]

This is why my computer and touchscreen monitor are mounted to a rolling cart next to the table. I didn’t want any connection between them and the table frame.

[Wsidr1]

I added to the thread title so others can find it in the future if they use the search button.

[holla2040]

Thanks, good idea

[holla2040]

That’s a good decision.

[holla2040]

Fixed my THC ground issue today. But first, while I had it apart, I powdered coated my mount arm (Prismatic Powder KTM Orange II), getting tired of black everything. I 3D printed an insulation sleeve, worked great. Passed the live test at 105.4V. Yay! Back in business.