Extruder switched off. MINTEMP triggered

Hello,

the original RAMP1.4 board burned out, so I got this one on ebay [www.ebay.com]. I thought it would be a simple replacement,
am I wrong! Now every time I run Pronterface, I get this error, "Extruder switched off. MINTEMP triggered." and something about machine shut down.

Even tho the two board identical, when I took a closer look of the board, it says"RAMSP1.4A" (I believe the RAMSP is a typo on the board) and the D10, D9 and D8 outputs are replaced by 10 Heat1, 9 heat2 and Heat Bed 8 respectively.

When I check the config.h in Marlin, there isn't one for RAMPS1.4A. I have tried the followings:

1.) the original config file that worked fine the motherboard was set to 33. Tried 34, 35, and 36. They all give me the same error.
2.) used a multimeter to check the extruder thermistor. It seems fine.
3.) used a multimeter to check the heat bed thermistor. It seems fine.
4.) Tried 3 different Mega boards. Same Error.
5.) Tried with and without any wires on RAMPS board. Same error.
6.) Tried short out extruder T pins. Same error.
6.) Tried close and open the extruder T pins


What should I do now?

Thanks in advance and Happy New Year!!

Edited 4 time(s). Last edit at 01/01/2016 11:24AM by rich1812.

Can't be sure it's the same thing but i had the same error for a megatronics v3 board with everything seemingly configured right. A month or so after i went to have it looked at and the guy just grabbed the latest marlin and it worked so could be something in the marlin version messing with the temp sensors but i can't be sure. did you get the newest version?

Thanks for the reply. I am not sure which version I have since I downloaded it a year ago. But I will give it a try.

I might have found the solution. But before I jump the gun, I need to confirm this is the right solution.
In the Marlin configuration.h
This block
// The minimal temperature defines the temperature below which the heater will not be enabled It is used
// to check that the wiring to the thermistor is not broken.
// Otherwise this would lead to the heater being powered on all the time.
#define HEATER_0_MINTEMP 5
#define HEATER_1_MINTEMP 5
#define HEATER_2_MINTEMP 5
#define BED_MINTEMP 5

now I changed HEATER_0_MINTEMP to 0, The error is gone ! Now my concern is if this will cause any harm to the heater. And it is weird that I have been using the HEATER_0_MINTEMP 5 for a whole year, I never had this error. Weird!

If it's been working fine for a long time, it seems more likely that it's caused by the thermistor briefly disconnecting and the temperature dropping below mintemp, if there's a break in the wire.

Setting it to 0 = disables the mintemp, effectively? Seems dangerous. If your thermistor disconnects (and not intermittently), this will happen: [forums.reprap.org]

edit: Nevermind, I derped. You just got a new board so this seems unlikely. Be careful though! Grabbing a newer version of marlin with thermal runaway protection is a good idea.

Edited 1 time(s). Last edit at 01/01/2016 07:07PM by nallar.

Thanks or the reply. I spoke too soon. After setting the HEATER_0_MINTEMP to 0, even tho the error message is gone, now I connected everything back, double check all wirings and wires, everything seems fine. But neither the bed nor the extruder heater will turn on . I am running out of ideas here. I try not to blame the board since it is a new board, what else could it be? Ahaaaaaaaaa!!!

Edited 3 time(s). Last edit at 01/02/2016 12:43PM by rich1812.

I've just gone through most of that above and discovered that the thermistor to ramps plug was sloppy. Pressed it home and all is now good.