Installing e3d Hotend

So last of this .. use one of your tables .. crank up the heat and put the measured temps in the script? Correct?

Use any table that is for 100K thermistor with 4K7 pullup. The simplest is to use the one you are already using if it allows you to achieve the temperatures you want.

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[www.hydraraptor.blogspot.com]

So I've installed and wired up the e3d hotend I had.
But, my problem is that I have something wrong, I think in the configuration.h file, but can't figure it out.

When I connect to the printer, with the extruder, not heated up, at room temparture it is returning a temp of 400 degrees.

I changed the settings in config_h to

#define TEMP_SENSOR_0 5
#define TEMP_SENSOR_1 0
#define TEMP_SENSOR_2 0
#define TEMP_SENSOR_BED 9 // 1 for Mendel90 kits 1-6, 9 for kits 7 onwards

But that doesn't seem correct. So is this the wrong config settings, or is something else the culprit here?

I think it must be a wiring fault because all 100K thermistor tables will give roughly the right reading at room temp as they are all 100K at 25C.

I think you must have wired the heater to the thermistor terminals to get a reading so high.

Edited 1 time(s). Last edit at 03/05/2015 05:31AM by nophead.

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[www.hydraraptor.blogspot.com]

Yep sure enough its the wiring, although not the thermistor. I actually got it to work fine by disconnecting the fan that is attached to the e3d hotend. So I must have this fan wired wrong. I had it wired to the heater and to the left pin "P", so I guess this is not the way it is supposed to be?

What did you ground the negative side of the fan to? Seems like it was the thermistor input line.

If you used the probe ground then it looks like you have the thermistor wires swapped at the Melzi. You should use the probe signal pin for fan ground as sharing the ground with with thermistor will cause a small error (not 400C at room temp though).

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[www.hydraraptor.blogspot.com]

I wired the ground (black wire) to the left probe (labeled P), and the 12v (red wire) to the left heater.

I suppose I could have the thermistor wires swapped at the Melzi, but I didn't change the Melzi wiring at all from before (when the printer was working with the Jhead end-no extruder fan).

You wouldn't notice the thermistor wires being swapped, the polarity only matters because it shares a ground with the probe. And I think the photo in the manual is incorrect. The wiring table is accurate. If you correct the thermistor polarity it should work but the reading may shift a bit due to the fan current dropping a small voltage in the ground lead to the thermistor.

The fan should be wired to the P and H terminals nearest to each other. At the Melzi end the spare ribbon wire intended for the probe can then be grounded using one of the limit switch terminals.

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[www.hydraraptor.blogspot.com]

That did it. Thanks so much. I would have never figured out that it was a wiring problem.