i3 pro C dual extruder MINTEMP error

[thegreen4me]

I have the i3 pro C and I have a problem which has just started. All 3 thermistors were working fine until today and suddenly the thermistor for extruder 1 now only shows 0 degrees and thus, a MINTEMP error. At first I unplugged all thermistors and checked each individually with a multimeter; all 3 showed a reasonable resistance. I then deliberately plugged the thermistor from extruder 1 into the port for extruder 2 and vise versa. It still showed 0 degrees for extruder 1 and 34 degrees for extruder 2, proving that the problem was not a bad thermistor.

I read in this thread that you can short the connection to the thermistor and it should show 358 degrees: http://www.geeetech.com/forum/viewtopic ... 13&t=17030
I tested that and when shorted with a jumper it did show 358 degrees and when I removed the jumper it immediately dropped back to 0 degrees.

The fact that I individually tested the thermistors plus the fact that switching them did not switch the problem extruder suggests the problem is with the control board, not the thermistors but the test I did with the jumper suggests there is nothing wrong with the board. I am now 100% stumped by this problem. Please help.

[William]

I have the i3 pro C and I have a problem which has just started. All 3 thermistors were working fine until today and suddenly the thermistor for extruder 1 now only shows 0 degrees and thus, a MINTEMP error. At first I unplugged all thermistors and checked each individually with a multimeter; all 3 showed a reasonable resistance. I then deliberately plugged the thermistor from extruder 1 into the port for extruder 2 and vise versa. It still showed 0 degrees for extruder 1 and 34 degrees for extruder 2, proving that the problem was not a bad thermistor.

I read in this thread that you can short the connection to the thermistor and it should show 358 degrees: http://www.geeetech.com/forum/viewtopic ... 13&t=17030
I tested that and when shorted with a jumper it did show 358 degrees and when I removed the jumper it immediately dropped back to 0 degrees.

The fact that I individually tested the thermistors plus the fact that switching them did not switch the problem extruder suggests the problem is with the control board, not the thermistors but the test I did with the jumper suggests there is nothing wrong with the board. I am now 100% stumped by this problem. Please help.

It's weird.I think we can rule out the two thermistors problem now.BTW,did you test the E1 port or E2 port?

[thegreen4me]

By e1 and e2 you mean extruder thermistor 1 and extruder thermistor 2 ports on the control board? I tested both. e2 is working flawlessly the only issue is with e1. I have been poking around with a multimeter for a while now and I found one more interesting thing that could be a clue. When I short either of the two working thermistor ports, I get 0.9 milliamps of current from the signal pin to the ground pin. When I do the same to the port that is not working, I get 10 milliamps. That seems excessively high for a thermistor port.

[William]

By e1 and e2 you mean extruder thermistor 1 and extruder thermistor 2 ports on the control board? I tested both. e2 is working flawlessly the only issue is with e1. I have been poking around with a multimeter for a while now and I found one more interesting thing that could be a clue. When I short either of the two working thermistor ports, I get 0.9 milliamps of current from the signal pin to the ground pin. When I do the same to the port that is not working, I get 10 milliamps. That seems excessively high for a thermistor port.

Ye，i mean that before.You can also test the voltage of the two thermistor ports,to see is it is the normal value,and the value is 5V around.

[thegreen4me]

I bought a new gt2560 control board, put it in and everything works now! I am however very disappointed in geeetech. They simply refuse to honor their warranty. I spent weeks trying to contact them about getting a replacement board. I tried contacting them by email, skype, and their site's livechat. They did not ever respond to me through any of those methods. Eventually I gave up hope of them ever answering and just spent $40 of my own money on a new board. Oh well, at least I got my printer working again and I learned not to trust this Chinese company.