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Author Topic: M999 Error  (Read 251 times)

dwilton

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M999 Error
« on: November 11, 2013, 04:50:10 PM »
Well I have assembled my Duo but I keep getting an M999 error.  I checked wiring, then metered the two thermistors.  One thermistor is reading about 8 ohms and the other one is reading about 80 ohms, which I am assuming is a bad thermistor.  Is that correct?

Thanks,

jit

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Re: M999 Error
« Reply #1 on: November 11, 2013, 10:52:24 PM »
Are you sure you are measuring the thermistors and not something else?  Thermistors are in the tens of thousands of ohms (90K ohms is typical for my thermistors, but it varies a lot with temperature).  Heater resistors are down in the range of ohms (between 3 ohms and 7 ohms, I think, depending on the model of hot-end).

To eliminate one possible source of confusion, measure resistances directly at the Azteeg terminals (screw terminals for the heaters, header pins for the thermistors).  Leave it wired up, and reach in with your probes.  It is safe to do this if you have removed all sources of power from the Azteeg;  shut down the power supply, unplug the USB cable, and wait a bit first.

(This may be obvious to you, but might fool some people who don't have a lot of experience with electronics:  If your meter has a range select switch, and you select the 200K ohm range, and the readout says 80.0, it's telling you 80,000 ohms...)
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dwilton

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Re: M999 Error
« Reply #2 on: November 11, 2013, 11:39:19 PM »
My bust, yes they were in K ohms.  One measures (now that they are at room temp) 60K and one measures 112K.  Yes, they have been removed from the circuit, just measuring the resister.  I watch the temp display on Repetier Host and the temperature starts out normal then jumps up to 300 degrees and starts jumping around (that is the thermistor measuring 60K).

jit

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Re: M999 Error
« Reply #3 on: November 12, 2013, 04:26:23 PM »
It doesn't sound right that they should be so different at the same temperature.  You could try swapping hot-ends;  maybe the other one will work better.
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whosawhatsis

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Re: M999 Error
« Reply #4 on: November 13, 2013, 09:11:20 PM »
Typical "room temperature" is roughly 90K (depending on the temperature of your room), and the resistance will decrease as temperature increases (they are NTC, or Negative Temperature Coefficient thermistors). I would disconnect the wires at the screw terminals on the X carriage and measure those to see if there's a problem with your thermistors and rule out a bad connection in that location as the cause.
« Last Edit: November 13, 2013, 09:13:31 PM by whosawhatsis »

dwilton

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Re: M999 Error
« Reply #5 on: November 14, 2013, 02:18:59 AM »
OK, when I bypassed the thermistor crimp connectors, everything seems to work fine.  Anyone know where I can get replacement connectors?    Somehow I don't think the alligator clips are a long term solution.  :D

whosawhatsis

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Re: M999 Error
« Reply #6 on: November 14, 2013, 02:32:11 AM »
Check the connection between the screw terminals and the wires that run to the crimped connectors. That's the most common cause of connection problems with the thermistors.

dwilton

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Re: M999 Error
« Reply #7 on: November 14, 2013, 02:59:11 AM »
It happened consistently after a couple minutes of heating (supporting a problem with the hot end theory).  I snipped the crimp out and put in two alligator clips between the resistor and the red wires going to the screw down block and everything works.  Now I just need a permanent replacements for the mechanical clips that I cut out.

 

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