Duet 2 Wifi power problem



  • Hi, this is my first post on the forum as I have always managed to sort out my problems reading the posts. But not this time.

    I have an Anycubic kossel with Duet 2 Wifi (v1.04c) bought in Nov 19 + Duex 5. Power is provided by a 600w ATX power supply providing separate 5v and 12v using the PS on pin.
    The printer has worked well for 7-8 months but I had a problem with it today. The printer initially turns on with 5v and the web server comes up fine.
    As soon as I press the ATX On button, everything goes off.
    To me it looks like the board has a short as the voltage drops when ATX is enabled and a message saying Vin has dropped briefly pops up.
    I can smell that something has overheated but there is no signs anything has burnt out.
    I have tried with all 3 fuses removed and only the positive wire and this still happens.
    Is there an obvious component I can replace that could fix this or is it time for a new board?

    Thanks in advance



  • hmm, have you tested the ATX PSU wihtout the Duet connected to it?



  • Good call bearer.
    I have an atx tester plugged in and everything is reading normal.
    I may have to go digging around for an old power supply to see if that fixes it. If not I may have to order a new one.
    I'll keep you posted.



  • Not sure I understood that post, the ATX PSU you were using is OK or not OK when you just connect the green PS_ON wire to ground on the PSU?



  • The power supply has voltages that are all correct 5v,12v etc.
    I have tried another atx power supply and unfortunately get exactly the same results. All works fine until I press the ATX Power On. The voltage drops and everything on the 5v turns off. If I press ATX Power Off quick enough the 5v carries on working. The board looks to be shorting out the 12v rail on the PSU. Something must have blown.



  • @memmop said in Duet 2 Wifi power problem:

    Something must have blown.

    yeah, just didn't make sense it keept doing it without the fuses in place.

    if you're inclined you can find the schematics here https://github.com/T3P3/Duet/tree/master/Duet2/Duet2v1.04

    editL the logical thing might be the wires for Vin are shorted; check if there is a single loose strand or something?



  • No the wires are fine.
    I've just wired it as a normal 12v psu and put the jumper for 5v back to int.
    Everything works fine. The motors, heaters, fans etc. Looks like the problem is with the Ext 5v/PS on connector.
    From this I looked at the schematics and the PS on circuit goes through TR7.
    It took some finding as it is tiny but I have found it and it is burnt out.
    IMG_20200703_195425.jpg
    IMG_20200703_195444.jpg

    I have another Duet Wifi that doesn't use PS on so I can swap them over.
    Thanks for your help with this.


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