I3 Prusa geetech HOT END faulty temperature readings

[Anghel Alexandru]

Hello all,

I have a Prusa I3 printer with Melzi 2.0 board.

I had some issues with the heater cartridge I took it out for cleaning once and I broke the thermistor or so. Since then I had this DEF error both on HEAT BED and HEAT END .
I now have replaced the thermistor with a 100Kohm one and when measuring at room temp I get about 100Kohm on both thermistors, for bed and HEAT END.

Problem is that I already reset the board a couple of times and no change. The HEAT BED works fine and when I start the printer the temp shows room temp or 0 degrees. But the HEAT END shows 245 degrees even when it's off.

That's the problem the HEAT END shows 245 degree's the thermistor works perfect it is new I triple checked it and gives a good value. I resest the printer several times by pressing the reset button for more then 10 second.
The red LED light after resetting the printer does NOT remains on, so my guess is that it can read the thermistors good ? But why does it says its 245 degrees when is actually 0 or room temperature ?

How can I fix this problem ?

Please advice greets

[William]

Hello all,

I have a Prusa I3 printer with Melzi 2.0 board.

I had some issues with the heater cartridge I took it out for cleaning once and I broke the thermistor or so. Since then I had this DEF error both on HEAT BED and HEAT END .
I now have replaced the thermistor with a 100Kohm one and when measuring at room temp I get about 100Kohm on both thermistors, for bed and HEAT END.

Problem is that I already reset the board a couple of times and no change. The HEAT BED works fine and when I start the printer the temp shows room temp or 0 degrees. But the HEAT END shows 245 degrees even when it's off.

That's the problem the HEAT END shows 245 degree's the thermistor works perfect it is new I triple checked it and gives a good value. I resest the printer several times by pressing the reset button for more then 10 second.
The red LED light after resetting the printer does NOT remains on, so my guess is that it can read the thermistors good ? But why does it says its 245 degrees when is actually 0 or room temperature ?

How can I fix this problem ?

Please advice greets

I think you can check if there is a short circuit in the HOT END thermistor,it there is not,you can exchange the HOT END thermistor with the HEAT BED thermistor to see if the HOT END thermistor though the value is normal.
Have a try plz.

[Anghel Alexandru]

hello,

not is not the thermistors like mentioned in the description. they are both 100kohm check them at connector so also the wires are not short.
I was wondering what the values should be on the heat end on the input pins on the melzi board, unconnected to the thermistor with power off so i can check

greets

[William]

hello,

not is not the thermistors like mentioned in the description. they are both 100kohm check them at connector so also the wires are not short.
I was wondering what the values should be on the heat end on the input pins on the melzi board, unconnected to the thermistor with power off so i can check

greets

Sorry,i learn a little about that board...But you can check if there are some issues on some ports of the board.
http://www.geeetech.com/forum/viewtopic ... 23&t=17030