Damaged New Duet WiFi - Repair Possible?



  • New user here. Experienced with Prusa machines, and RAMPS based printers. New to Duet. Building a Hypercube Evolution with Duet WiFi.

    Herewith a tale of woe, and a request for info and assist.

    While wiring up my Duet I managed to make two fairly disastrous mistakes on two separate days. Firstly I connected in two expensive Noctua fans for hotend and print fan and managed to burn out both. I had 5v fans and my Duet came with the fan voltage header set to Vin which in my case is 24v. Two brand new Noctua's ruined. Thoroughly disappointed in myself when I figured out what I had done. Set the fan jumper to 5v and paid out for two more Noctua's.

    Today the new Noctua's arrived. Having been once bitten I powered up the Duet and grabbed my meter to make doubly sure there was only 5v on the fan headers, before I connected the new Noctua's. Disaster struck. I had just registered 5v on the meter when I received a text message. Instinctively I glanced at my phone and one of my meter probes slipped slightly. Instantly there was a slight spit and a wisp of magic smoke. I shut off the power and removed the Duet from the HEVO.

    Clearly I have killed the board. When powered on the 3.3v LED remains off, so does the wifi chip blue LED. Looks like I may have killed the 3.3v circuit. Examination under the magnifier reveals two areas of damage, what looks like a converter and a 14 leg IC.

    I have highlighted the two visibly damaged items in red. Can anyone confirm what damage I have caused, and is it going to be possible to get this board repaired?

    Thanks in advance!

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  • No one can tell for sure... but probably.

    The slip very likely put 24V on the 5V rail on the board. This blew these two chips physically. The question is, did it harm anything else, something that does not show through the chip case. The only real way to tell is to replace those two and see what else works or not. Maybe, just maybe, the regulator blew without overvolting the 3V bus.

    I don't work for Duet, so I can't tell you anything about their repair. If you are even medium handy, and can get the chips, "ChipQuick" solder really does work, for "re-work".

    So... you might try a Mouser or DigiKey order, for those chips and some ChipQuick. Obviously, one of them is a regulator, and you could potentially use equivalent parts that came in the same case.



  • Oh, and the other blown chip MIGHT be the USB interface. It is in about the right area of the board, and a USB chip would have at least one 5V pin.

    You might want to NOT replace it... unless you actually plan to 'need' USB at some point. I don't believe I ever plugged anything into the USB of my several Duets. I did "initial connect" by editing the SD card.

    I do use one USB now, but only because I got a Palette Pro 2. Not a lot of people are going to combine that with a Duet.

    .

    Maybe just replace the regulator and see what happens. In fact, I think I'd start with the regulator, and using chipquick to just remove that other chip, and see what works/doesn't.



  • ive blown U2 on my board before, cpu was fine but i also had to replace the wifi module and the sd card, so if you power the board and the wifi module gets very hot rather quickly it is likely dead


  • administrators

    I'm sorry to hear of your misfortune. The other blown chip is U11, which is the mosfet driver. It's cheap to replace, and one user recently managed to recover his Duet by replacing it. However, if 24V got shorted to 5V then it's likely that more than 3.3V got fed to the processor, WiFi module and SD card. If the SD card isn't burned and is still readable in a PC then you may have been lucky. If the SD card is burned, then probably the processor and WiFi module are blown too. Does either of them get hot?



  • @dc42

    Thank you for replying so quickly. The SD card appears to be completely dead. Nothing on the board heats up when it's powered but from what you say it looks like my slip may have been terminal. I may try to replace the regulator and u11 later and try my luck. I've ordered a replacement Duet, and learned a painful lesson.



  • Thanks to all that replied, much appreciated.


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