Marlin temperature settings

We have the following problem,

The heater of the 3D printer 12v- 40w gets hot only after warming the thermistor manually above 5 degrees. After we heat it up manually there is no problem and we can print. However when we don't manually heat up the Thermistor then it will not heat up at all. The electronics and the 100 NTC G540 (thermistor) and extruder work like a charm after the manually heating so they are fine. We already have replaced the RAMPS 1.4 and the Thermistors with new ones.
The temperature in Pronterface and on the LCD screen are the same as we measure with an IR temperature meter.
When we don't manually heat then in Pronterface we can't activate the temperature and it shows T 0/0.


When I change the settings in Marlin to #define HEATER_0_MINTEMP 0 it still doesn't heat up. We have tried 4 different Thermistors and they all gave the same result so that's not it.

When we use these settings nothing works unless we pre-heat manually.
#define HEATER_0_MINTEMP 5
#define HEATER_0_MINTEMP 5
#define HEATER_0_MINTEMP 5
#define BED_MINTEMP 5

I hope someone here has some suggestions on how to fix this problem it must be some Marlin setting that we have to change or can it be Pronterface?

Thanks in advance

Edited 1 time(s). Last edit at 08/19/2015 04:51PM by ray23.

Did you selected\set the correct TEMP_SENSOR settings?

Edited 1 time(s). Last edit at 08/19/2015 07:49PM by Frans@France.

Usually the environment temperature is higher than 5°C. Are you printing in an icehouse?
The 100 NTC g450 isn´t listed in the marlin setting, so choose type 1 for starters.

What temp does the bed thermistor show in pronterface?
Did you define the right board type in marlin? ( 33 is EFB )
Did you use the right pins for the thermistors? (Above the z-stepper connectors)
-Olaf

@ Frans in france The sensor is not listed but even when you choose the wrong setting it should still heat up according to what I have read online, but the temperature is then off. Besides that we have tried all of the listed thermistors settings and no result.

@ Olaf We also don't understand why the thermistor doesnt give us room temperature (20°C no icehouse ;-) in Pronterface.
We have chosen setting 1 and all the others already and no result.
The boardtype is 33 EFB

We have placed the hermistors on
T0 extruder
T1 heatbed

The heatbed also gives 0 in Pronterface.

I'm puzzled what can cause this problem because we already have replaced the ramps 1.4 and the thermistors so they can 't cause the problem.

I hope you have some more suggestions thanks

Edited 3 time(s). Last edit at 08/20/2015 05:01AM by ray23.

If the used thermistor is not listed then maybe building your own table is the solution. Information about the procedure: [reprap.org]

Or if you have the specs you might calculate them:
Example spreadsheet [www.thingiverse.com]
or [github.com]
or Nophead's blog entry [hydraraptor.blogspot.fr]

When you manually heat up the thermistor, what is the lowest temperature you see on the LCD ( beside 0°C )?
Can you confirm your Ramps boards have 4.7kOhm resistors populated? ( three resistors beside the capacitors at the thermistor ports stamped "472" )
What is the resistance of the thermistors when NOT connected to the Ramps?
-Olaf

@ Frans@france thanks for the links it's a shame that in Holland I can't find one of the thermistors that is mentioned in Marlin, but the one we are using is being sold for usage with 3D printers.

@ Olaf When I hold the thermistor between my fingers I will get 5°C maximum.
I can confirm that R22, R21, R11, R1 and R7 are 4.7kOhm and the resistance is 472.
The resistance of the thermistor when not connected is 100

Thanks for your help guys I really appreciate it.

Ray23, if you can't get the right thermistors in Holland, what about one of these? [e3d-online.com]

Richard

@ RGN01 I like to order everything in Holland because of the paying system we have. I don't have a creditcard and it takes longer to order when I go abroad But I can get the right Thermistor in Germany however the Thermistor that I have bought here should also work just fine. Thanks for the suggestion.

Quote
ray23
@ Olaf When I hold the thermistor between my fingers I will get 5°C maximum.
I can confirm that R22, R21, R11, R1 and R7 are 4.7kOhm and the resistance is 472.
The resistance of the thermistor when not connected is 100

Do you try to use a PT100 directly on your board? That will not work.

---

Triffid Hunter's Calibration Guide

--> X <-- Drill for new Monitor

Most important Gcode.

I googled "100 NTC G450" and an Epcos 100k NTC G450 showed up ( thermistor, not thermostat )
But maybe they sent you something else, because a standard 100k thermistor would read around 80k-90k at room temperature, not "100"
-Olaf

Quote
RGN01
Ray23, if you can't get the right thermistors in Holland, what about one of these? [e3d-online.com]

Richard

Achatz in Holland should have the right thermistors, too.

Beste Groeten
Olaf

Edited 1 time(s). Last edit at 08/21/2015 03:25AM by o_lampe.

Or reprapworld in Den Haag, and pay using iDeal (http://reprapworld.com/?products_details&products_id/393/cPath/1591_1600_1613)

@ Olaf it is indeed a 100k epcos Thermistor I checked this with the supplier and this one is listed in Marlin so it should work I'm puzzled why it doesn't work. Thanks for the address in Holland.

@ wurstnasse We don't have a PT100 (I'm not sure what you mean by this ) we use a Epcos 100k and connect this to the pins on the ramps4.1

When you measured 100Ohm it is not an Epcos.

---

Triffid Hunter's Calibration Guide

--> X <-- Drill for new Monitor

Most important Gcode.

@Wurstnase it wasn't 100 but 90 my bad sorry about that.

Quote
ray23
@Wurstnase it wasn't 100 but 90 my bad sorry about that.

It should be >90000 Ohms at room temperature!

---

Triffid Hunter's Calibration Guide

--> X <-- Drill for new Monitor

Most important Gcode.

Yes 90k that is correct

Het bleek een fout in de arduino Mega 2560 te zijn. Nadat we deze hadden vervangen voor een andere was het probleem verholpen.

Edited 1 time(s). Last edit at 08/25/2015 12:39PM by ray23.