Wrong connection of 3dtouch in duet maestro

RodrigoRMaraujo

Hello everyone.
I connected a 3dtouch probe (trianglabs) to a Chinese Duet Maestro board by mistake. Now the power supply via the USB cable is getting so hot that the USB connector is burning my fingers. Connecting it to a 24V power supply makes one of the LEDs light up, but the board does not connect to the local network.
Did I permanently burn the board or is there something I can still do?
Thanks to anyone who can help.
(sorry for the Google translate, I'm in Brazil)

droftarts

@RodrigoRMaraujo Unfortunately, that sounds pretty terminal. Not sure what will have failed, but most likely it's shorted out the MCU (main processor). When plugged in, check if the MCU or SD card socket get hot. You could try checking this page: https://docs.duet3d.com/User_manual/Troubleshooting/Duet_wont_respond
Note that the LEDs on your board are probably all green (keeps the cost down on Chinese clone boards), but they should be in the same order.

Ian

RodrigoRMaraujo

@droftarts
I read the content of the link you sent, thank you.
Yes, it gets a little hot under the main processor, but you can keep your finger on the board. However, it is not possible to touch the USB and SD card connectors, as they get very hot in just a few seconds!

It really seems like I joined the list of people who managed to burn a Duet, lol.
I have already ordered a new board.
Thank you very much for your reply.

dc42

@RodrigoRMaraujo on the Maesto the components most likely to fail when they are subjected to excessive voltage are the SD card and the W5500 Ethernet chip. So remove the SD card, then power up from USB again and see whether anything is still getting hot.

RodrigoRMaraujo

@dc42 thanks for replying.
I removed the sd card and the connector still gets very hot, and very fast. I can't even keep your finger touching the USB connector.

dc42

@RodrigoRMaraujo what else is getting hot? Check the W5500 chip in particular.

RodrigoRMaraujo

@dc42
I can feel the W5500 and SAM4S8 warm, almost cold, I imagine that they are in normal operation (but I don't know anything about electronics). What really draws attention and makes it impossible to connect the Maestro via USB cable is actually the USB connection port, which gets very hot very quickly. About 30 seconds later, even the USB cable gets hot. I turn it off for fear of burning my USB power supply.
When I connect the Maestro to the USB, only a blue LED next to the USB connector lights up, but very weakly. The other LEDs on the board do not light up.
If you want me to do any more tests or connect the conductor directly to 12/24V, just let me know!
Thanks.

dc42

@RodrigoRMaraujo if neither the ATSAM4C processor nor the W5500 chip is getting hot, it's likely that some other IC has failed, possibly the 5V or 3.3V regulator IC. The heat generated neat the USB port is probably coming from the diode that connects the USB power to the main 5V power rail.

I doubt that it's worth trying to attempt to repair the board. RRF versions later than 3.5.x don't support the Maestro as its processor does not have floating point hardware.

RodrigoRMaraujo

@dc42 thanks for replying!
I really wasn't thinking about fixing the board, there's no one in my area who can do that.
I've already ordered a new board to replace the one I burned. Since it's a very basic printer, I believe the RRF 3.5 will be perfect for me.
For the other printers, I have the Duet 2 WiFi and "Fysect Big Dipper" boards, and with these I'll be able to keep up with the new versions of the RRF.
I'm going to keep the Maestro that I burned as a souvenir so I don't do this kind of stupid thing again, lol.
Thanks!