New Duet WiFi not reading thermistors correctly



  • Hi Guys, I just got my Duet WiFi this morning and I was excited to see it. So I installed it, and already having a working config.g for the rostock max v2 I was quick to setup. After I connected it to my WiFi I turned on the printer to start printing, but alas I have an issue.

    ; Thermistors and heaters
    M305 P0 T100000 B4061 R4700 L0 H30 ; NTC-3950 bed thermistor, beta adjusted for 60-100C
    M305 P1 T100000 B4388 R4700 L0 H30 ; Semitec 104GT-2, beta adjusted for 220C.

    Is what I have listed for the Thermistor settings.

    Should I change something or did I get a defect?



  • How is it not reading correctly?

    If it's 30C too high, remove the H30.



  • I removed the 30 just to test and now it reads like -48 or something ridiculous.



  • Just for testing purposes, I changed H to H125 and I got a positive reading, albeit only 3.7c it still flashes to error. For now I am just testing USB power, didn't wanna turn on the main just yet.



  • Please check this thread:

    https://www.duet3d.com/forum/thread.php?id=247

    Specifically my comments regarding the VSSA fuse.


  • administrators

    @sLpFhaWK:

    Hi Guys, I just got my Duet WiFi this morning and I was excited to see it. So I installed it, and already having a working config.g for the rostock max v2 I was quick to setup. After I connected it to my WiFi I turned on the printer to start printing, but alas I have an issue.

    ; Thermistors and heaters
    M305 P0 T100000 B4061 R4700 L0 H30 ; NTC-3950 bed thermistor, beta adjusted for 60-100C
    M305 P1 T100000 B4388 R4700 L0 H30 ; Semitec 104GT-2, beta adjusted for 220C.

    Is what I have listed for the Thermistor settings.

    Should I change something or did I get a defect?

    You don't appear to have said what problem you have.



  • @sLpFhaWK:

    I removed the 30 just to test and now it reads like -48 or something ridiculous.

    His problem seems to be very low temperature readings.



  • Sorry you're right i didn't list my actual issue.

    my temps are negative then flashing to error. i guess i blew that fuse, how i have no idea but now i don't know how to fix it.

    i read elmorets link and i don't have any of those fuses on hand and even if i did i'm not comfortable performing surgery on a day old board i paid a lot of money for.

    can't even go back to the rambo because all the connectors are now different. 😞


  • administrators

    It does sound like the VSSA fuse has blown. It's the rectangular white ceramic component in the box labelled F1 behind the WiFi module. If you have a multimeter, you can check it by measuring its resistance with power and thermistors disconnected. It should read just a few ohms.

    To get it replaced, I suggest you contact whoever you purchased the board from. But you also need to fix the fault in your wiring that caused it to blow. Typically it is a short between a thermistor wire and a heater wire.



  • @dc42:

    It does sound like the VSSA fuse has blown. It's the rectangular white ceramic component in the box labelled F1 behind the WiFi module. If you have a multimeter, you can check it by measuring its resistance with power and thermistors disconnected. It should read just a few ohms.

    To get it replaced, I suggest you contact whoever you purchased the board from. But you also need to fix the fault in your wiring that caused it to blow. Typically it is a short between a thermistor wire and a heater wire.

    i contacted Tim Elmoret already. maybe if i purchase a second duet wifi from him i can send in this and he can swap it out for me?

    Tim that work for you?



  • First it is important to confirm that it is the VSSA fuse - have you performed dc42's check?

    As for a repair, I will talk to the manufacturer about that - Filastruder is just a distributor, so we need to operate under Think3DPrint3D's guidance.



  • i haven't been home all day to check it.

    when i'm home i will definitely check it per davids instruction.



  • I was actually just taking to David about this the other day. I do electronics repairs on the side and would be happy to offer a Duet repair service for folks in the US. Fuses, drivers, or even the MCU would be no problem.

    If there is any interest in something like this, just let me know.

    @elmoret:

    First it is important to confirm that it is the VSSA fuse - have you performed dc42's check?

    As for a repair, I will talk to the manufacturer about that - Filastruder is just a distributor, so we need to operate under Think3DPrint3D's guidance.



  • I tested that fuse and nothing happened, so I'm assuming it's that fuse.



  • Hey W3DRK,

    Where abouts are you located? I noticed your offer a wide regarding performing electronics repairs and I'm potentially interested, obviously dependant on (amongst others of course) the fairness of your pricing to perform light duties such as replacing the VSSA fuse on a Duet WiFi – in on a roll the past few months -- if we include today's mishap, I've got four boards all in need of the VSSA fuse replacement. I honestly am at a loss for words on this topic -- I seem to have a real knack for popping these little guys.

    While on the subject, I was hoping maybe David or another of the geniuses (being serious -- no sarcasm whatsoever here I promise) her can answer a quick question in this subject -- I know from a recent thread where I pleaded for answers regarding my temperature sensing issues that one the VSSA fuse is popped, that none of the thermistor inputs will work until corrected, though in an effort to at least get back up and running whilst my pack of boards is in the hospital, I'm left wondering:

    if the VSSA fuse also is tied in to the ability for the WiFi boards to read via another means such as PT100? I have a number of the little breakout boards that plug into the duet wifi expansion port (not sure of the proper name for that particular port, but I think it's 10 pins maybe 12 pins IIRC). It weighed be pretty cool to at least be able to get online using one of the platinum sensors temporarily, at least.

    Thanks as always, and hope everyone is getting on better than I have been lately. 😉

    Jonathan


  • administrators

    The PT100 and thermocouple daughter boards do not depend on the VSSA fuse.

    If you are blowing VSSA fuses, that strongly suggests that you have a short between a thermistor wire and a heater or fan wire. Possible causes include:

    • Your print head or effector is running into some metalwork that is shorting connections together
    • You have a short circuit (perhaps intermittent) inside your heater cartridge between the element and the case, along with contact between a thermistor wire and the hot end metalwork


  • I thank you for your reply, but while what you are saying is undoubtedly true, in my case that was an issue once or twice, but more recently I've come up with creative ways of causing these sorts of shorts to occur; the most recent of which was that a print was about to begin and the leveling routine had begus when i rnoticed there was a glob of filament just below the nozzle so I paused the machine and, with apair of tweezers, carefully went to pinch and remove the excess filament to avoid it mucking up my first layer. When I contacted the nozzle with the tweezers, I witnessed a small quick spark (which shouldn't have happened – not sure if the reason might have been static electricity in my body when approaching the nozzle that somehow instigated this zap of charge sufficient to blow the fuse -- but that's what happened nonetheless) ...annoying....

    thanks and have a nice day.

    --jonathan


  • administrators

    Interesting! I would be surprised if static electricity could be sufficient to blow the VSSA fuse because I wouldn't have thought there was enough energy in a static discharge. I will research the topic. It does seem very plausible to me that driving filament through a Bowden tube and then extruding it can build up static charge. Perhaps it would be a wise precaution to ground the hot end metalwork to prevent charge building up. To do this safely would require a separate ground wire to be run to the hot end from the ground side of the power supply output.


 

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