Hotend Will Not Heat Up

Hello Friends;

I have only one issue that is keeping me from printing my first 3D part. Obviously, nothing can be printed without a functional and dependable hotend. All of my other components are working except this. I am hoping someone had a similar problem and is willing to walk me through. I am a newbie this is my first attempt at building a 3D Printer.

PROBLEM
Hotend will not heat up.
When printer is turned on and connected to Proneterface I attempted to heat up the hotend by depressing the “set” button for the heater. Almost immediately I got the following status message:

BACKGROUND
I am building this 3D Printer entirely from scratch.
These are the components I am using in the build:
ARDUINO MEGA 2660
RAMPS 1.4 SHIELD
V6 BOWDEN EXTRUDER HOTEND
This is the software I’m using:
Marlin 1.1.9
Pronterface (Printrun 1.6.0)
Windows 10

This is my Marlin settings:

Pronterfaac indicators
One thing I’ve noticed is the hotend temperature show 0degres C before I connect the printer to Ponterface. However, as soon as I connect the printer the hotend temperature Pronterface shows is -15 degrees C. This is probably why I get the MINTEMP error.

I tested the thermistor and it reads 100 ohm indicating to me that its is properly functioning.

QUESTION
How do I correct Pronterface hotend temperature to read a more correct room temperature of approximately 24 degrees C?
I would appreciate any help anyone can offer.

Please let me know if additional information is needed.

Thank you,
Calvin

Have you set the correct thermistor type in the Marlin FW thermistor table?

Also, did you check for any shorts or cable breaks between the thermistor and the Ramps board?

Edited 1 time(s). Last edit at 07/07/2019 03:50AM by Ohmarinus.

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http://www.marinusdebeer.nl/

-15 indicates one of two issues

1) the thermister is not plugged in, or has a broken wire, or is plugged into the wrong place on the controller.
2) the mega is damaged and not reading its ADC correctly.

You cant heat up when the thermister doesn't read a sane temperature

I appreciate the quick response. Thank you.

Is there a way to test the Mega board independently? The thermistor is brand and and has correct independent readings. I'm not sure how to test the Mega's handling of the ADC. I've replace the complete MEGA and RAMP components twice now and get the same reading.

you did select the correct MOTHERBOARD in configuration.h? as with that wrong, it looks at the wrong pins for temperature
It should be #define MOTHERBOARD BOARD_RAMPS_14_EFB

The analog input on the mega can be tested with basic arduino knowledge eg [www.arduino.cc]

The thermistors are on A13 (T0) A14(T1) and A15(T2)


To be absolutely sure please provide a photo of your controller and indicate where you plugged in The hot end thermistor (Should be T0 plug)

Quote
cdaileyjr

I tested the thermistor and it reads 100 ohm indicating to me that its is properly functioning.

Thank you,
Calvin

You say your thermister is reading 100ohms have never seen one the reads 100 ohms at room temp.
All my thermister's read 100K ohms at room temp.

Quote
cdaileyjr
The thermistor is brand and and has correct independent readings.

Explain how a thermister can have an independent reading, does it have its own display. What thermister do you have.

Edited 1 time(s). Last edit at 07/07/2019 05:45PM by Roberts_Clif.

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Computer Programmer / Electronics Technician

I apologize, its 100 Kohms. I get my reading by connecting the multi-meter to the thermestor.

I've attached a pix of my setup. To simplify things I only have the heater and thermistor plugged in.

Why is your hotend across D9 and D10??

It should be on D10 and the + right next to it

Great observation! I correct the hotend wiring. However, because of the distorted room temperature Iof -15 degrees, I still get the MINTEMP error which prevents the hotend from heating up.

Is your ramps fully down on the mega? (ie you cannot see the metal pins between the ramps and the mega)

Are you sure all pins went into the appropriate plugs? It is possible to force the ramps on and miss a block of pins

I really appreciated all of your comments and suggestions.
I just went a purchased a complete MEGA and RAMP set up again.
Guess what, I now get the proper initial room temperature setting of 23 degrees C. And it heats up to the selected PLA temp.

I guess I will never really know what went wrong the first time.

I will now put everything back together again. I will let you know how things go with the printing phase.

Thanks again to you all.

Calvin