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    Troubleshooting a possible electrical failure

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    Duet Hardware and wiring
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    • KP0005undefined
      KP0005
      last edited by

      While playing around wirh aluminum hwatsinks and a powered Duet Maestro, I encountered a short and a bright spark. I powered off the machine, removed the short, powered it on again and went checking for malfunctions. Fortunately, everything appears to be working an the PCB doesn't have any charred spots.

      Basically, how do I find out exactly how badly I screwed up? From what I can tell, I shorted the motor voltage supply (24V) to the heater voltage supply (12V).

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      • KP0005undefined
        KP0005
        last edited by KP0005

        Here's what m122 gave me:

        m122
        === Diagnostics ===
        RepRapFirmware for Duet 2 Maestro version 3.1.1 running on Duet Maestro 1.0
        Board ID: 08DAM-9F9GA-J24TD-6J1DA-3SS6J-TN1GV
        Used output buffers: 1 of 24 (11 max)
        === RTOS ===
        Static ram: 21924
        Dynamic ram: 95612 of which 44 recycled
        Exception stack ram used: 356
        Never used ram: 13136
        Tasks: NETWORK(ready,472) HEAT(blocked,1304) MAIN(running,1996) IDLE(ready,84)
        Owned mutexes:
        === Platform ===
        Last reset 00:09:06 ago, cause: power up
        Last software reset at 2020-07-23 18:27, reason: User, spinning module GCodes, available RAM 13392 bytes (slot 2)
        Software reset code 0x0003 HFSR 0x00000000 CFSR 0x00000000 ICSR 0x0400f000 BFAR 0xe000ed38 SP 0xffffffff Task MAIN
        Error status: 0
        MCU temperature: min 40.3, current 41.3, max 44.5
        Supply voltage: min 0.0, current 24.2, max 24.3, under voltage events: 0, over voltage events: 0, power good: yes
        Driver 0: standstill, read errors 0, write errors 0, ifcount 10, reads 21832, timeouts 0
        Driver 1: standstill, read errors 0, write errors 0, ifcount 10, reads 21832, timeouts 0
        Driver 2: standstill, read errors 0, write errors 0, ifcount 10, reads 21832, timeouts 0
        Driver 3: standstill, read errors 0, write errors 0, ifcount 7, reads 21835, timeouts 0
        Driver 4: standstill, read errors 0, write errors 0, ifcount 10, reads 21832, timeouts 0
        Driver 5: ok, read errors 0, write errors 0, ifcount 0, reads 0, timeouts 21842
        Driver 6: ok, read errors 0, write errors 0, ifcount 0, reads 0, timeouts 21841
        Date/time: 2020-07-23 23:08:58
        Slowest loop: 40.74ms; fastest: 0.13ms
        I2C nak errors 0, send timeouts 0, receive timeouts 0, finishTimeouts 0, resets 0
        === Storage ===
        Free file entries: 10
        SD card 0 detected, interface speed: 15.0MBytes/sec
        SD card longest read time 2.6ms, write time 0.0ms, max retries 0
        === Move ===
        Hiccups: 0(0), FreeDm: 169, MinFreeDm: 166, MaxWait: 31775ms
        Bed compensation in use: none, comp offset 0.000
        === MainDDARing ===
        Scheduled moves: 19, completed moves: 19, StepErrors: 0, LaErrors: 0, Underruns: 0, 0  CDDA state: -1
        === AuxDDARing ===
        Scheduled moves: 0, completed moves: 0, StepErrors: 0, LaErrors: 0, Underruns: 0, 0  CDDA state: -1
        === Heat ===
        Bed heaters = 0 -1, chamberHeaters = -1 -1
        Heater 1 is on, I-accum = 0.2
        === GCodes ===
        Segments left: 0
        Movement lock held by null
        HTTP is idle in state(s) 0
        Telnet is idle in state(s) 0
        File is idle in state(s) 0
        USB is idle in state(s) 0
        Aux is idle in state(s) 0
        Trigger is idle in state(s) 0
        Queue is idle in state(s) 0
        LCD is idle in state(s) 0
        Daemon is idle in state(s) 0
        Autopause is idle in state(s) 0
        Code queue is empty.
        === Network ===
        Slowest loop: 32.88ms; fastest: 0.01ms
        Responder states: HTTP(0) HTTP(0) HTTP(0) HTTP(0) FTP(0) Telnet(0), 0 sessions
        HTTP sessions: 1 of 8
        Interface state active, link 100Mbps full duplex
        === Filament sensors ===
        Extruder 0 sensor: ok
        
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        • A Former User?
          A Former User
          last edited by

          @Matej101 said in Troubleshooting a possible electrical failure:

          From what I can tell, I shorted the motor voltage supply (24V) to the heater voltage supply (12V)

          The Maestro doesn't have different motor and heater voltages so if you're using a 12v heater then its presumably an external power supply?

          KP0005undefined 1 Reply Last reply Reply Quote 0
          • KP0005undefined
            KP0005 @A Former User
            last edited by

            @bearer

            I use two different power supplies for my printer.
            24V to power the Duet
            12V to power hesters and fans
            Since all PWM channels are doing the switching on the ground side, it's just a matter of connecting the "+" wire to the 12V supply instead of the Duet.

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            • KP0005undefined
              KP0005
              last edited by KP0005

              and the two PSUs have connected grounds to make this work

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              • Phaedruxundefined
                Phaedrux Moderator
                last edited by

                If it's powering up and responding as expected that's a pretty good sign. You could post some up close high quality photos of the board in case we can spot something damaged. But you may have got lucky.

                Z-Bot CoreXY Build | Thingiverse Profile

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                • A Former User?
                  A Former User
                  last edited by

                  You might have cut down the lifespan for the 12v supply and anything else connected to that, but I don't think the duet cared.

                  KP0005undefined 1 Reply Last reply Reply Quote 0
                  • KP0005undefined
                    KP0005 @A Former User
                    last edited by

                    IMG_20200723_233741.jpg

                    This is the affected area.

                    I believe I shorted one of the surfacr mount components to the top pin on the hotend heater connector.

                    The component likely had 24V on it, because during the short, my 12V LED strip shone much brighter than it does normally.

                    The bottom pin is the switched ground, so it has been connected to the 12V supply via the heater element.

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                    • A Former User?
                      A Former User
                      last edited by

                      Oh, right, but I still stand by my previous statement, the duet probaly didn't care, but as you noticed the LED strip would have a shorter runtime due to the extra voltage, but its hard to quantify. Any fans or other 12v stuff would have the same issue.

                      The only potential damage to the duet would be from the additional current involved, but most places connected to Vin are quite large on the Duet, and the current wouldn't have passed through any component on the Duet. So again, I don't think the Duet cared much about that particular short.

                      1 Reply Last reply Reply Quote 1
                      • KP0005undefined
                        KP0005
                        last edited by

                        Thanks for the reassurances 😃

                        In the meantime, I'll try to continue using the board and report any issues I can find.

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