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MAX TEMP Error - Runaway Temperature -

Finished construction of printer and turn on. After about 2 minutes the temperature of the hotend rises until it reaches 300 which triggers a MAX TEMP alarm and makes a loud repeating beeping. I have confirmed that the temerature is in fact correct with my handheld IR probe. Tried selecting PLA profile in the LCD and that has no effect. Fans are all working. The fan that blows air over the fins of the hotend (extruder fan) is on at 50 and above, and the print fan doesn't turn on with everything plugged into the rambo board... I tried turning on the print fan manually with a 12volt battery and that added another 30 seconds before temp climbed to 300.

It seems the rambo board is running max power to the hotend and doesn't stop. It even climbs past 300 unless i manually turn it off.

Answer this question I have this problem too

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I had the main power plugged into the extruder/bed input and the extruder/bed plugged into the power input. So backwards. Anyways swapped that around and changed a 5 amp fuse to fix it. Back in action.

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chris will be eternally grateful.
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