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Extruder and bed do not heat up
#1
Just got a davinci 1.0 and installed repetier 0.91 on it.
LCD indicates bed and extruder temp are both 0.
RepetierHost says bed temp is 20C and extruder is -20C
Heating either the bed or extruder shows no change in temperature; direct IR temp measurements show no change.

Is there something I need to do to set up my new installation?
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#2
I just read the thread on the heated bed sensor initializing with defect.
I turned off my printer, hit my extruder with a hot air rework gun for a minute, then turned my printer back on and now the extruder reads the expected temperature.

The same fix for the heated bed must also be applied to the extruder thermistor!
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#3
Ok thanks for the information - and pushing issue in tracker - will work on it next week for one and two extuders

but just to clarify it is not a fix - it is a workaround for hardware problem - I do not know if it is done on purpose by xyz or if they have different sensor supplier that have slow response time sensor - I am not electronic expert but this behaviour seems weird for me
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#4
Agreed it's not a real fix. I played with the extruder some more; after turning it off, it reaches -2C in about 5 minutes; I didn't have to time to let it run longer but will try that later.
So I believe there is a calibration issue; for example I was able to extrude ABS at 215C (same ABS reel takes 235C on my thing-o-matic).

To determine if the thermistor is bad one would need to know:
1) What type
2) Remove the thermistor and run some actual tests at 0C and 100C

OTOH, as I understand how thermistors are used, they are part of a voltage divider. Perhaps the fixed resistor value is incorrect?
Any schematic for the thermistor hookup?
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#5
yes I guess there is some issue with the thermistor table for some sensors
http://reprap.org/wiki/Thermistor
from another point of view the feedback from nepenthy was the temperature after warm up was same as extruders and then stable - and no need to warm up after, the temperature should quickly drop to -20 if no heat when printer is power on
is your extruder temperature drop after you stop the warm up ?
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#6
That is correct, the temperature begins to drop and goes into the negative range.
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#7
so that is different behaviour I think - and this means wrong thermistor table for sure
I think doing a preheat won't help a lot - as it means you need to print right after power on the printer - the best is to find /change the table in configuration.h
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