Temp Sensors Hi - I'm getting an odd temp reading on the extrude head of my reprap mendel. The reason I'm at this point is because I was getting MINTEMP warnings and realised something was awry - so I replaced the resistor first then the thermistor, hit the temp buttons and the thermistor went pop as it reached 200c - might have been a dodgy component - kinda doubt it though and has never done that before. I seem to get through resistors but not thermistors. Startup is using:- M304 H0 B3480 R4700 T10000 M304 H1 B3960 R4700 T100000 M105 gives me:- ok T:47.0 /-273.1 B:20.6 /-273.1 @:0 I'm pretty certain the room temp is closer to 20.6 than 47! So to test I swapped the board connections over and sent the following:- M304 H1 B3480 R4700 T10000 M304 H0 B3960 R4700 T100000 M105 gives me:- ok T:23.1 /-273.1 B:19.3 /-273.1 @:0 These look closer to reality and understand thermistors are more accurate at working temps so I'm fairly happy with these. Meter readings (@200k) on sensors are:- Bed 12.5 Heater 128 The question is, can I run the printer with sensors switched and why the odd readings? Thoughts? https://reprap.org/forum/read.php?1,286141,286141#msg-286141 Mon, 16 Mar 2026 20:32:51 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?1,286141,286141#msg-286141 Temp Sensors https://reprap.org/forum/read.php?1,286141,286141#msg-286141
The reason I'm at this point is because I was getting MINTEMP warnings and realised something was awry - so I replaced the resistor first then the thermistor, hit the temp buttons and the thermistor went pop as it reached 200c - might have been a dodgy component - kinda doubt it though and has never done that before. I seem to get through resistors but not thermistors.

Startup is using:-

M304 H0 B3480 R4700 T10000
M304 H1 B3960 R4700 T100000

M105 gives me:-
ok T:47.0 /-273.1 B:20.6 /-273.1 @:0

I'm pretty certain the room temp is closer to 20.6 than 47!

So to test I swapped the board connections over and sent the following:-
M304 H1 B3480 R4700 T10000
M304 H0 B3960 R4700 T100000

M105 gives me:-
ok T:23.1 /-273.1 B:19.3 /-273.1 @:0

These look closer to reality and understand thermistors are more accurate at working temps so I'm fairly happy with these.

Meter readings (@200k) on sensors are:-
Bed 12.5
Heater 128

The question is, can I run the printer with sensors switched and why the odd readings?

Thoughts?]]> spezzer General Sun, 29 Dec 2013 12:08:13 -0500