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[I hate wires] Further troubleshooting assistance needed -- 3D printer circuit

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  • [I hate wires] Further troubleshooting assistance needed -- 3D printer circuit

    1) Connector on motherboard for heater, pins generate 12 volts.

    2) White wires to extruder show proper conductivity (no short) and proper voltage with heater disconnected.

    3) Thermistor tested good over a candle-flame, registers heat. Connections to extruder board are sound.

    4) Attach heater to wires, voltage at motherboard drops to ZERO and heater does not heat.

    5) Further testing shows both "original" heater and "replacement" heater has identical resistance ratings.

    6) There is no step six proceed to step seven at this time.

    7) Applying voltage to heaters with benchtop power supply, heaters become very hot (as they should) within a short period of time.

    8) Returning known good heaters to machine, machine will not heat when reassembled. Voltage at connection drops to zero when heater load applied.

    9) Replaced extruder module with known good unit from identical machine across town -- will not heat. Repaired unit will heat in identical machine across town.

    10) XYZ has been unacceptably silent on the issue.

    So... Motherboard fault out on me somehow? That's the only thing I can think of. As soon as it senses a load it cuts the voltage to the heater.

    If that's the case it explains why XYZ went dark when I asked for additional troubleshooting.
    This is the ending.... still your need is driven on (driven on) as we trigger one more bomb...

  • #2
    I'd check the power supply. The 12 volt rail may be faulty, showing full voltage only under no load.

    At the end of the project, there is a profound difference between spare parts and left over parts.

    Location: SF East Bay.


    • #3
      If bypassing the controller board and running 12v directly to the heater makes the heater work then the board is probably bad.


      • #4
        I still have my other PLA-only machine operational, this is seriously backing me up I need to print ABS.

        I emailed them my findings they assure me the problem is the "heater wire assembly" and they are sending me a new one overnight. I emailed them back and asked if there could be a problem with the board, they assure me the fault is in the "heater wire assembly." When asked about the possiblity of a board fault they go around in circles about the "heater wire assembly" and refuse to elaborate on what it is. idea what that even means but I'll wait and see. Now watch them send me something like the heater PSU or some kind of SSR or what not. They are VERY Asian this may come down to a case of ADHD on my part and translation challenges between us.

        That said if I get this piece and the fault continues I'll pull the trigger on a different machine from a different supplier -- I want a dual-head out-of-the-box solution anyway. If it comes down to it the DaVinci machine will make an excellent source of wee stepper motors and drive pieces. *evil grin*
        This is the ending.... still your need is driven on (driven on) as we trigger one more bomb...


        • #5
          I've owned two different TAZ 3D printers, one was decent but too small. Current and last machine.... MakerGear M2, it just works.
          Retired - Journeyman Refrigeration Pipefitter - Master Electrician - Fine Line Automation CNC 4x4 Router


          • #6
            When I've tried communicating technical problems to Asia it usually takes me about 3 or 4 emails to get them to absorb all the details. And that's when they actually want to help. I'd ask them for a motherboard schematic.


            • #7
              From your statements, the power supply is not holding up under load.

              If you are sure the load (heater) is ok, then the power supply has a problem. That sort of problem is perfectly possible, but less common, so you need to be certain that there is no issue with the wires, etc.

              Having the assembly work on a different unit, but not on this one is a very good test, though. If "everything" is same, wires, heater. etc, and it works in one but not the other, power supply is almost certain as the problem, unless some visible fault is present that only affects one unit.
              2801 3147 6749 8779 4900 4900 4900

              Keep eye on ball.
              Hashim Khan

              It's just a box of rain, I don't know who put it there.


              • #8
                Not necesarily the power supply, but rather whatever component functions as the switch between the power supply and the heater. The device has failed and is acting like a high resitance. When there is no load the 12V is there, but under load the 12V at the heater terminals goes to 0.

                Can you point us to a schematic of the board that drives the heater?


                • #9
                  I asked for one was told this is "XYZ Exclusive And not for public viewing, sir."

                  Little bit more information.

                  Machine has a heated bed as well, also driven off 12 volts. That heats up just fine, comes up to the programmed setpoint real quick.

                  The extruder however, the heater is driven from a different connection on the MB.

                  Now the connection for the heat-bed draws power, heats up nicely and doesn't seem unstable. 11.8VDC

                  The one for the Extruder says 11.5VDC at the meter, and drops to zero when I put a load on it.

                  So, electrical-wizards... My next leap-of-logic is to disconnect the heated bed and see if the heater for the extruder comes up. If it does... that tells me something. What... I don't know.

                  If it doesn't I wonder if that heated bed connection has enough balls to drive the nozzle (12vdc @ 35 watts) in addition to the heated bed... 12VDC at 40 watts.

                  I mean what is the worst that could happen --

                  This is the ending.... still your need is driven on (driven on) as we trigger one more bomb...


                  • #10
                    It looks like the heater is controlled by an 8-pin MOSFET Q1, and there appear to be some LEDs indicating presence of 12V, 5V, and 3.3V. You might be able to measure some of these components to see that the resistor values are correct, and you should be able to see the LEDs light if things are OK. The MOSFET would be more difficult to test in circuit, but if you can determine which pin is the gate, it should have at least 4 or 5 volts on it when the output is (supposed to be) on. If you have a small soldering iron, you could re-solder the SMT components near the heater jack.

                    Another test would be putting various loads on the heater connection to see if it incorrectly senses an overcurrent at some point. A small 12V automotive lamp would be a good test, although an incandescent load draws a lot when cold and might trigger the overcurrent protection. Best would be a 10-15 ohm resistor which would draw about 1 amp and 12W.

                    Good luck!
                    Paul , P S Technology, Inc. and MrTibbs
                    USA Maryland 21030


                    • #11
                      Pretty simple you take the power for the heated bed and connect to the Extruder, if it works the board is bad and PSU is fine. This is assuming both are 12 volts, some like mine use 24 volts on the Extruder.
                      OR jumper from the PSU 12 volt source to the board and power the Extruder off that when the HBP is also powered on.

                      I have owned several Chinese made machines with boards that had bad solder connections, a little work with a soldering iron and your good to go.
                      Last edited by wmgeorge; 10-28-2015, 05:59 PM.
                      Retired - Journeyman Refrigeration Pipefitter - Master Electrician - Fine Line Automation CNC 4x4 Router


                      • #12
                        I got through to someone at XYZ they are going to call tomorrow morning and walk me through a diagnostic procedure. We'll see how that goes.

                        Busy at the moment, I'll post some more pictures of the main board after dinner.
                        This is the ending.... still your need is driven on (driven on) as we trigger one more bomb...


                        • #13
                          Further developments: They will be calling a second time tomorrow with more information. Turns out the machine has a diagnostic mode that dumps to an SD-micro on the underside of the board. They are looking over the data and at the moment are leaning twords a new motherboard.

                          When I attach the extruder heat to the the heated bed terminals I get heat. Both systems heat up quickly.

                          Problem is the extruder overheats as the signal from the thermistor goes to the defunct extruder heat terminals.

                          Now on paper I could switch the thermistor signal wires so the thermistor on the extruder controls the heated bed terminals.

                          HOWEVER this leads to software issues because now it thinks the heated bed is over heating and goes into shutdown.

                          This can be worked around by flashing the board and installing a custom Repiter Host firmware... as many other pissed off XYZ owners have done. Now I understand their frustration.

                          Waiting for XYZ to call back before I start perma-modding the machine. Lets see what they come up with.
                          This is the ending.... still your need is driven on (driven on) as we trigger one more bomb...


                          • #14
                            I have seen a similar problem on computer power supplies. the connections in those little connectors can become heated and eventually the metal oxidizes and creates a high resistance joint that does exactly what you are experiencing. My guess is that the connector is toast and must be replaced (probably means motherboard in your case). You can test this to some extent by using automotive bulbs in a series/parallel configuration to get the resistance you need. Then watch the voltage build up across the connector - indicating an oxidized metal connection.
                            Glenn Bird


                            • #15
                              I do NOT understand why the heated bed which only sees 180-200 degrees has those heavy duty screw lugs and heavy insulated leads. Same voltage, same amps as the extruder.

                              The extruder heater is powered by that dainty little Molex connector and much thinner wire.

                              If this was a case of cost-cutting then both systems would be powered off of Molex connectors not just the extruder. To me this shows a willful level of planned failure of a critical part.

                              Funny how XYZ is trying to position itself as the premier entry-level home grade printer... they've signed deals with Walmart, Barns and Nobel and other consumer-side retailers to market these things.

                              NO ONE is going to pay $500 for a machine that fails suddenly in a very technical way. That's on top of the rape-level charges for material of their own branding.

                              I'm starting to not like these guys very much, especially considering I've already TOLD THEM I WANT A REPLACEMENT BOARD and they want to play "diagnostics" with me. I'll send the other board back even, just get me back up and running already. :P
                              This is the ending.... still your need is driven on (driven on) as we trigger one more bomb...