I recently built the PicoEMP PCB using the design files from the GitHub repository and had the board assembled by a manufacturer in China. However, I encountered an issue where the Q3 MOSFET failed during operation (damaged).
I wanted to ask for your insights regarding potential causes and troubleshooting steps.
Have you encountered similar MOSFET failures in previous builds?
Are there any recommended modifications to improve reliability?
Before replacing Q3, are there specific voltage measurements I should take to diagnose the issue?
First try after arming i measured around 200vdc on j3 then falling down to 1.1v and never increased after that to 200vdc during arming and i am measuring 0v on J1 and 7v on Q2
What is the normal voltage should i measure? And what components should i change in plus
My guess would be bad luck (component failure - there are random ones early, OR an ESD event as the MOSFET gates are rather sensitive).
It’s also possible that if Q3 is held on (or “partially on”) it could have excessive heating. R5 should pull down Q3 most of the time so that won’t happen, and R4 limits current to prevent damage to it or T1. But it’s still a low-cost build so things aren’t perfectly protected.
But we’re using them for many hours without issues is why it might just be bad luck.
If the MOSFETs are sourced from unknown suppliers as well there could be more issues there. I’d probably replace it and hopefully be done with it!
We occasionally saw soldering issues on the transformers as well, being the leads mostly underneath can be harder to inspect.
