How to check for dead Teensy 4.1 board

gndTeensy

Member
Hi everyone.

I believe I have a dead Teensy 4.1 board. I plugged the USB and it did not turn on. So I measured the voltage on the 5V and 3V pins. The voltage are 2V and 1.5V respectively.

Any thoughts?
 
While something is clearly wrong, perhaps good news is this looks different than the usual destroyed Teensy (typically from touching 5V or higher power to 3.3V which destroys the main U1 chip). A normal destroyed Teensy will usually measure something like 0.3 to 0.9 volts on the the 3.3V pin, because there is a "short" inside a chip. But at the same time, the 5V pin will usually measure almost 5 volts. Usually the F1 fuse and U4 voltage regulator will be very hot, but it's easy to mistakenly identify nearby areas as the hot spot because the ground planes inside the PCB conduct the heat to nearby parts.

Only 2 volts on the 5V pin really looks like whatever is trying to supply power to Teensy isn't working. Maybe an unpowered hub that's already straining to supply power to other USB devices? 1.5V on the 3.3V power line is more than we usually see when a Teensy is destroyed (chips shorting the power), so my guess from only these 2 numbers is maybe Teensy just isn't getting good power and the 1.5V is what the voltage regulator can do when its input is only ~2 volts.
 
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