I think I killed my Duet 3 Mini 5+ Wifi

dc42

@hrkrx can you tell us how you miswired the fan plug? Then I may be able to work out what happened.

5V and 3.3V faults on the Duet 3 Mini are rare, because the IO pins on it are fairly well protected against miswiring. The pins on the stepper driver daughterboard connector and the SPI daughterboard connector are not protected. However, there are TVS diodes on the 5V and 3.3V rails. If you are getting neither 5V nor 3.3V and your PC reports that it draws too much USB power, then I think it is likely that the 5V TVS diode has failed. This is component D10 on your board, located close to the TEMPDB connector.

hrkrx

@dc42 I used the 2 Pins directly beside Laser/VFD

And I am not getting an 5V or 3.3V (according to the indicator LEDs)

Thank you for helping

EDIT:
I am not very knowledgable about TVS diodes, but I just measured D10 with the big pads left and rigth and it shorted in both directions

dc42

@hrkrx it should be safe to connect a 12V fan to that connector, provided you get the polarity correct.

It does sound to me that the TVS diode has shorted. That may be the only component that has failed. In your position, I would remove the TVS diode (which is tricky without the correct equipment), then apply USB power only and see whether the board responds and WiFi is working. If it is then I would connect a bench PSU to VIN and gradually increase the VIN voltage above 5V while measuring the 5V, 3.3V and 12V rails, to see if the 5V and 12V regulators are doing their job (taking care not to let the 5V rail exceed 6V). If they are then a new TVS diode should be all that is needed.

dc42

PS - does the square IC next to L5 look OK? That's the 5V regulator. It should look the same as the square IC next to the other inductor, under the same lighting conditions. If it's failed short circuit, then that would overheat and blow the TVS diode.

hrkrx

@dc42 The area around that chip got pretty warm, but not too hot to touch.
also as shown on the pic im my first post, the area around L5 was rather dirty, I cleaned it now with alcohol and a brush.

are there more accessible leads to measure the regulator?

also the pics from the 2 regulators:

hrkrx

I removed the TVS diode and connected via USB. That worked and I could connect to the board.

I will try the bench PSU next.

hrkrx

I supplied up to 6V to VIN and measured 5V at IO_0 5V_EXT, and it did not stop at 5V but got almost to 6V, I assume that means the regulator is also dead?

dc42

@hrkrx said in I think I killed my Duet 3 Mini 5+ Wifi:

I supplied up to 6V to VIN and measured 5V at IO_0 5V_EXT, and it did not stop at 5V but got almost to 6V, I assume that means the regulator is also dead?

Yes, it looks as though the regulator has failed short circuit. 5.2V or a little higher is normal when 5V_EXT is not loaded, but not 6V.

hrkrx

@dc42 I just looked online where to get the TS30041-M000QFNR, but there are delivery delays for at least 2 month for low quantities, but it should be fine to use external 5V and disable the internal 5V, shouldn't it?

dc42

@hrkrx yes you could remove the regulator IC and use external 5V power.