Hot end temperature not rising beyond 140 C

Hello all,
For Mono Mendel,

I am facing problem with Hot end temperature. It is not rising beyond 140 C.
Checked the thermistor resistance which is around 85K for room temp.

Can anyone help?

[reprappro.com]

Here is what I got :


SENDING:M503
echoteps per unit:
echo: M92 X87.489 Y87.489 Z4000.000 E660.000
echo:Maximum feedrates (mm/s):
echo: M203 X300.000 Y300.000 Z3.000 E45.000
echo:Maximum Acceleration (mm/s2):
echo: M201 X800 Y800 Z30 E250
echo:Acceleration: S=acceleration, T=retract acceleration
echo: M204 S1000.000 T1000.000
echo:Advanced variables: S=Min feedrate (mm/s), T=Min travel feedrate (mm/s), B=minimum segment time (ms), X=maximum xY jerk (mm/s), Z=maximum Z jerk (mm/s), K=advance_k
echo: M205 S0.000 T0.000 B20000 X15.000 Z0.400 E15.000
echo: M206 X0.000 Y0.000 Z0.000
echo: M208 X210.000 Y210.000 Z140.000
echoID settings:
echo: M301 P12.000 I2.200 D80.000 W125
echo:Thermistor settings: M304 Hh Bb Rr Tt, H0=Bed, H1..n=nozzle, b=thermistor beta value, r=series resistor, t=thermistor resistance as 25C
echo: M304 H0
B3988 R4700 T10000 M304 H1
B4138 R4700 T100000
FPU Enabled no

how about some machine details

What type of controller?

what type of thermistor do you have

what are your thermistor setting in your configuration.h

Have you verified the temperature with an external temperature probe? Ie have you determined if its just reading wrong or really not heating up?

Mono Mendel should be the middle iteration of RepRapPro Mendel, with a Melzi board. Thermistor settings that are actually being used will be the EEPROM output posted. The legacy settings on the site I linked match except they show a beta of 3960. If the hot end or thermistor has been swapped that would be useful information.

If you have no thermocouple you can run some filament that should barely melt at the temperature you're indicating and try pushing it through by hand. You could also (with the power off to the machine) unhook the heater circuit from the Melzi and check its resistance.

What's written on the Melzi could also be relevant. The R parameter on the M304 command there is 4700 which is right for what the design was supposed to be, but some of the Melzis got 10k pullup resistors. If I remember how that works, the error should be in the other direction if that were your problem.