Power Supply Problems



  • Duet Community,

    I've just received a Duet 2 WiFi and 7" Panel Due, and I'm happy to be joining you guys (finally)!

    That being said, I do have one question: When connected to my computer via USB, everything works flawlessly (with the 3.3v and 5v LEDs illuminated). When connected to my power supply (measured at 24.2v), I only get the blue Vin LED illuminated, and there doesn't seem to be any signs of life on the logic level (e.g. WiFi). If connected to my 24v supply and USB, everything goes back to business as usual.

    Now I know what you're thinking. This guy didn't RTFM or look up his problem. The 5v jumper is in the wrong position! Unfortunately, things ain't gonna be that simple. The jumper is in the right position currently, but I've also tried it in the other position (EXT 5V EN). The only occurrence of a similar problem (where the jumper wasn't the solution) that I could find had a mention of a blown 5v regulator. Looking at the schematic for my board (rev. 1.04c), the 5v regulator module seems to be labeled "U3." I've included a picture of said regulator, although it looks completely fine to my untrained somewhat trained eyes.

    Hopefully I'm missing something glaringly obvious, which which ends up being a super simple fix.

    Thanks!!

    5V Regulator



  • @Zeezeehorn said in Power Supply Problems:

    rev. 1.04c

    should have a 7.5A mini blade fuse close to the Vin connector, if that isn't blown then U3 will likely be the failure despite lacking any obvious visual clues.



  • @bearer Checked the 7.5A fuse and it's not blown. I suppose I'll wait for a bit to see if anyone else can chime in, then start an RMA 😢



  • @Zeezeehorn with the fuse ok and int_5v jumper in place then the problem is the 5v supply circuitry which mainly consist of U3.

    @Zeezeehorn said in Power Supply Problems:

    If connected to my 24v supply and USB, everything goes back to business as usual.

    what voltage does the web interface show for Vin when powered by both Vin and USB?



  • @bearer Web interface reports 24.2V


  • administrators

    Can you confirm that you have nothing connected to the Duet, except VIN power? Just to be sure, disconnect the PanelDue.



  • @dc42 Correct, nothing else is connected. I'm actually yet to even connect the PanelDue, as I was intending to get the basic functionality working before adding it.


  • administrators

    @Zeezeehorn, I'm sorry that your Duet appears to have a faulty 5V regulator. Assuming it's genuine Duet, please contact your reseller for a replacement under warranty. Refer them to this email for authorisation.



  • @dc42 No worries, it happens. Is there any further testing I can do to help you guys out diagnose the problem for the sake of design revisions / QC?