Damaged duet wifi

lolorc

Hi,

I've damaged my duet board. I think I've created a short on my breakout pcb while changing my nozzle.
All leds but the 3.3V do light up. I just hope it only the 3.3V reg.

the board doesn't show up as an usb device, nothing on the esp serial port, no wifi connection either. When I do power the board, both the bed and the heater start to heat up.
the 3.3V output give 0.5V and the 5V output gives 4.8V.

Now I've removed the 3.3V reg, I measure 1.4ohm between 3V3 and GND.
I guess it's worst than I initially thought, I must have killed everything on the 3V3 bus
I don't know exactly what happen on the breakout pcb, but there's 3V3 and 24V, i hope I haven't shorted 24V and 3V3

Would you have any advice to help me diagnose this issue further ?
I guess the 1.4ohm between 3V3 and GND when everything is unplugged is not normal.

Thanks in advance.

–
Laurent

lolorc

sdcard must be dead, it's not recognised by my computer anymore.
resistance between 3V3 and GND is 12.2ohms without the sdcard inserted

Qdeathstar

12 ohms of resistance is pretty low. What is the resistance with your hotend assembly disconnected?

dc42

Which type of Duet it?

It does sound to me that you had over voltage on the 3.3V rail.

EDIT: you mentioned WiFi in your post so you've answered my question. The Duet WiFi has a special MOSFET driver circuit that ensures that the hotvend and bed are off if 3.3V is not present. The fact that this is not working means the driver chip has failed, and the only likely cause of that is a voltage much higher than 5V on the 3.3V rail.

Unfortunately this means that all or most of the chips connected to 3.3V have probably failed.

lolorc

what do you mean by hotend assembly ? the heater cartrigde ? it's 14ohm (40W, 24V one)

lolorc

Hi David,

Thanks, I did not see your answer yesterday.
I guess it's not repairable at all

lucky me.

lolorc

I guess I secretly wanted to support you and buy another one (better smile than cry)
I've seen there's a rev1.01 on it's way, what are the changes ? (are they related to the ethernet version ?)

dc42

Rev 1.01 has been in production for a while. The changes are minor, to do with how the noise filtering capacitors on the thermistor channels are grounded.