pronterface - wrong temperature reading

Hi there,

I just finished building my reprap last week and printed a calibration part without any major problems. Today when I turned on pronterface I got incorrect temperature readings for both my heated bed and my hot end. According to pronterface, the ambient temperature of my living room is around 300 degrees Celsius.

I have to admit, after the printer had cooled down after my first print, I unsuccessfully tried to take of my hot end for some small adjustments and i wasn't very gentle. I figure it didn't come off because the filament was attached to the hot end. So today I figured i would let the hot end get up to temperature to remove it.

I thought, maybe I damaged the hotend thermistor in my rough attempts to remove it, but as far as I know that shouldn't affect the heated bed temperature reading.

I'm using sanuinololu 1.3a, grrf 100k resistors. I don't know if this is a problem or not, but my LM7805 voltage regulator gets pretty hot. I figured that is to be expected because well, it's regulating voltage.

I attached a screenshot of the pronterface screen with the wrong temperature reading. your help will be greatly appreciated.

Did you check the cennections on the board. That looks like you shorted the temp pins together. Since both are now reading way off. Or pulled/broke one pin connection.

The ADC's can get weird with one floating pin. So a broken extruder thermister could scree up all the ADC inputs. So try unplugging each thermistor one at a time and change your firmware settings to disable the one unplugged. That will tell you if one is broken. If it goes back to normal with one but not the other... Well replace that one.

Just a thought.