Duet3 6XD Power Issue

Glen_Remix

Good morning,

Tl;dr: New 6XD board 5v-3.3v regulator doesn't seem to be working.

I am working on a project where I am integrating a Duet-powered machine with industrial automation hardware.

I was using a Mini 5+ for initial testing but opted to change to the 6XD due to the optoisolated I/O making PNP hardware easier to work with.

After removing the Mini 5+ and changing all of the wiring to suit the new board, I unwrapped the 6XD and plugged in the USB to set up networking.

Unfortunately, I wasn't able to connect to the board via USB and the board wasn't coming up in Device Manager.

I noticed that although the USB and 5V LEDs were lit, the 3.3V wasn't. I also noticed that the 5V-3.3V regulator U4 gets very hot as soon as the board is plugged in.

I have nothing else plugged into the board, and have tried powering on both with and without the SD card.

Is there anything else I could try, or is this a hardware failure?

Grateful for any help.
Thanks,
Glen

markz

@glen_remix I can't answer your question, but I do have a 6XD and did run it with just the USB power successfully. So, it should work as you have it.

You might hook a voltmeter up to one of the 3.3V outputs and check the voltage on it with/without USB power.

Glen_Remix

@markz Thanks for your reply.

So interestingly there is 3.3V to the IO (measured at IO_0).

However, there doesn't seem to be an internal 3.3V. At the 5v-3.3V regulator U4, which I mentioned was heating up, I measured 4.6V at the input, but only 0.5V at the output. This regulator is listed as "Output for internal use only" in the schematic.

I don't know if there is a way of testing this, or if a warranty return is the best option?

Thanks,
Glen

markz

@glen_remix The IO outputs are from a different regulator (3.3V_ext) so I'd guess you're pointing at the root cause (U4 + 3.3v output path). Maybe give the Duet3d folks a day to respond but it looks bad.

Phaedrux

When and where did you purchase your Duet3?

Also, can you see if there is 3.3V on pin 8 of the SPI DB header?

Glen_Remix

@phaedrux Purchased on 17/08/2022 directly from Duet3D as an OEM.

Getting 0.5V on SPI pin 8, same as the regulator output.

Thanks,
Glen

Phaedrux

Please send an email to warranty@duet3d.com and CC your reseller. Include a link to this forum thread and the details of your original purchase. You'll receive a reply with a form to fill out.