No 3,3Volts after mistake

  • Hello,

    i own a Duet Maestro, on building my printer i shortend the GND from "always on" Fan J24 with - from PWM Fan0 J25.
    Now i knew it was a terrible idea.
    The 3,3Volts LEd was off.
    I replaced the U2 low drop reg, because i measured on the Out only 0.6 volts
    but after replacing this part the 3.3 Volt rail is still dead.
    can someone give me tipps to repair my Board?


  • @dc42 @T3P3Tony - any ideas?


  • administrators

    If after replacing the 3.3V regulator you still don't get 3.3V on the 3.3V rail, then something is shorting it to ground. Remove the SD card if it is still in the socket, and if the 3.3V rail is still missing, check which chip or chips on the board are getting hot.

    Note, there are 2 different versions of the 3.3v regulator with different pinouts. The one used on the Maestro does not have R near the end of the part number.

  • The regulator has no "R" in the part number.
    I have removed the Sd Card an its still no power on 3.3V
    i had an Piezo orion to the Board connected when i damaged it and the Orion is broken.
    had to Power the Board half an hour but could not identify a chip that is very hot.
    It seem to me that i have not enough skill to repair the Board. thats to bad.

  • administrators

    Can you confirm that you have nothing connected to the board except USB power?

  • Today i tried it again.
    Only Power from USB.
    Sd Card removed.

    I found that U10 is getting very hot.

  • administrators

    U10 is the W5500 Ethernet chip. Looks like it has failed. If you have the right hot air equipment and vacuum pick tool to remove it, you could do so. I think the Maestro should boot up without it if you don't enable the network with M552 in config.g.

  • Thank you for help, but i think this it not possible for me.

  • Surely a nearby reprapper can help you out, or a makerspace or something?

    If recycling is your only other option hit me up with a chat and we can have a look at postage rates, but unless you happen to be my neighbor I fear the Norwegian postal rates are anything but reasonable.

    Best of luck!

  • The W5500 chip itself is a TQFP chip, it has legs, if you do not have the hot air equipment, you can simply use a knife to cut all the legs.

    After that, you also want to use a soldering iron to remove the legs from the PCB one by one, you need to do this just in case the knife bent the legs into short circuits.

    In the end, it's still a lot easier than hot air

  • @frank26080115
    thank you for your Idea. I removed the chip with a
    scalpel and the Board is back on Track.👍

    Will the Board can used normaly when i replace the W5500?

  • administrators

    @harbo said in No 3,3Volts after mistake:

    thank you for your Idea. I removed the chip with a
    scalpel and the Board is back on Track.👍

    Will the Board can used normally when i replace the W5500?

    Yes if you replace the W5500 then the Ethernet will probably work again, as long as you didn't cut through any traces when you removed the chip. You will need to remove the legs of the old IC if you haven't already, without lifting the PCB traces (caution: when heated, they lift very easily!). After that you can solder the new chip in place. Make sure you get it the right way round. You will probably get some solder bridges, which you can remove with solder wick.

  • Great news!
    (Its a trick I will add to my bag of tricks for when I find myself without hot air or IR:)

    Its never easy to predict cascading failure but if the board works without the W5500 and the new regulator then I'd say you have good odds with replacing the W5500 and getting the board fully functional.

  • Great. I will try it. I have nothing to lose.
    Now i must find a shop where i can buy the Chip for a private person.

  • administrators

    If you are in the EU, try If you are in the US, Mouser and Digikey sell them.

  • @dc42

    Thanks for the link to the shop.I ordered one an will look if i can solder it.

    A big Thank you to the Support from the Manufacturer and the Users of this Forum.
    It is magnificent.

  • I recieved the W5500 today and soldered in his Place.
    It was a bit tricky but the Board and the Network are alive.👍 ☺

  • I must say this thread was a fun read.... Congrats on fixing your board.

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