I'm running a RAMPS 1.4 kit that I assembled myself from ultimachine.com with Kliment's Sprinter firmware and Pronterface/ReplicatorG.

Initially I connected my heater to pin D9 on the board and realized D9 is for the fan. In ReplicatorG, I could get the heater to heat up by clicking on fan enable, the LED for D9 would turn on and I could see the thermistor readings.

Now, whenever I have my heater on D10, it won't turn on and the red LED for D10 doesn't turn on when I send commands from either ReplicatorG or Pronterface. However, it does turn on if I first preheat the heater by connecting the heater to D9, pass current through it by clicking fan enable for a few minutes, disconnecting, shutting down, switching heater to D10 pins, restarting and reconnecting. The heater works only after carrying out this sequence.

Any advice on what could be causing this would be appreciated

-ak

Edited 1 time(s). Last edit at 01/15/2012 11:19PM by d4rwen.

Whats the temperature reading from a cold heater? Sprinter wont enable if if it reads below 5C. Probably a safety measure written by someone from a warmer climate. You can change that value in config.h, but if you're ambient temperature isn't really that cold you might want to calibrate your temperature sensor.

Ah yes, it looks like this was due to a faulty thermistor. The ambient temperature reading was 0 degrees Celsius (suspiciously low since my thermostat is set at 21 degrees Celsius and I don't feel like an icicle). It seems like the thermistor was open circuited until I forced the temperature up very high by connecting the heater to the fan pins. Then the thermistor's resistance lowered enough to get an ambient temperature that was far above 5 degrees Celsius.

I replaced the thermistor and it works like a charm.

Thanks for the suggestion