Hi,
I have a problem with extruder sensor constantly reporting 738 deg.
if I put Bed sensor connector in extruder connector and it correctly registers 21 deg.
I checked all the wiring and connected sensor DIRECTLY on the connector and I still have this issue.
I ordered new extruder sensor and I have exactly the same issues. Even when connected directly on connector it reports 738 deg 
Please help.
The temp you are seeing indicates a short.
Unplug therm 1 from the board.
Check the resistance on the wires not the board.
At room temp you should see around 100K ohms of resistance.
How can I get a short if I connect sensor directly to the board connector (no wires).
At first I thought I got the malfunctioned sensor but the brand new replacement I got acts the same so I’m puzzled.
The bed sensor read 105K ohms at room temp (and it shows correct 21 deg) and the old and new extruder sensor read ~9 ohms (and they both show 738 deg).
Is it possible I got lucky and got two bed sensors in a row or can it be something else?
It is possible that you got 2 defective thermistors.
When you unplug therm 1 does the temp go to 0C?
If it does then swap therm 1 and therm 2 to see if the error follows.
When you say you got 9 ohms on the extruder thermistor did you measure it through the wires or on the thermistor with out any wires connected?
Yes - when I unplug the therm 1 sensor I get a reading of 0 deg.
If I connect bed sensor (by default connected to therm 2) on therm 1 I get correct room temperature reading; same as if connected on therm 2. And vice versa - if I connect extruder sensor (old or new) on therm 2 I get 738 deg.
So I should report again to support and wait 14 days on new sensor ;(
I got K8200 for my birthday in beginning of December and it is still not working ;(
Ok,
Since when you unplug therm 1 and the temp goes to 0C this says the control board is ok.
Once again you have a short in the wiring.
You need to check the wires that go to the connector and the wires that go to the thermistor.
From your earlier comment it sounds like you have not checked the wires to the connector under the shrink tubing.
Hi WrongWay.
Thank you for helping me. I really appreciate it.
Both Therm1 and Therm2 are work correctly with the bed sensor; showing correct room temperature - so board is working correctly.
Can you please explain how can I have a short in wiring if I connect extruder sensor directly on the board (with no wiring whatsoever!) ?
I get incorrect reading on Therm1 and Therm2 with the Extruder sensor.
Again I have no wiring - I connect sensors directly on the board.
I also get incorrect resistance reading on both extruder sensors (only 9 ohms).
Thank you again.
DAVID
Ok,
Now I understand.
It is strange but it sounds like you have (2) defective thermistors.
Sorry for the confusion.
Hi,
Today I receiver my 3rd replacement sensor from Velleman.
To my surprise it all acts the same
If I read the resistance on the sensor I get ~7 ohm on all sensors. No wiring! I just put sensors on the multimeter.
I would really appreciate if someone can explain what I am doing wrong and how to repair it.
Thank you,
DAVID
David,
Are you sure your meter is reading correctly.
It’s very strange that you have 3 different thermistors that read the same.
If you have a 100K resistors check it with your meter the connect it across the leads of therm 1.
DO NOT TURN ON THE HEATER while this is connected.
You should get a reading around 23C.
This will check your meter and the board.