hot temp run away

Hi

I have a problem with my orusa hot end, the temperature continues to climb regardless of what temperature I set it to.

Any ideas on what the problem is?

Regards
Keith

What model of hotend, thermistor, electronics, firmware, control software are you using ?

When you say it continues to climb, is that what is reported by the reprap control software you use, or something you notice by another way of measuring temperature ?

Please detail how your hotend thermistor (or other kind of heat measurement device) is plugged (pictures would be nice).

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Most of my technical comments should be correct, but is THIS one ?
Anyway, as a rule of thumb, always double check what people write.

Hot end: j head 0.5mm mark iv-b
Thermistor: stock
Electronics: Sanguinololu 1.3a
Firmware: arduino
Software: pronterface

I set the temp to 180 and to monitor. The temperature climbs steadily and doesn't stop at the preset set. This is confirmed by smell and hot end dripping, so there is a definite issue.

The thermistor has two wires that plug into the board in the top left corner of the board, connections and wires appear to be in good condition.

I haven't used the printer for a few weeks and never had the problem prior to yesterday. I uploaded the firmware thinking this would fix it, but nothing changed.

Help?

Here are the pictures

Since your able to read the temp, Im thinking the thermistor is fine.

Witch leaves the firmware, and FET and micro to check

It sounds like the firmware is fine, if it can read the temp and turn on the heater it should be able to turn it off.

If you just turn it on and leave it the hot end does stay at room temp? (ie its not always heating is it?)

If your up to some soldering swap your two FETs over and see if the issue swaps to the Hot build platform.

If it does its the FET, if it doesn't I'm suspecting the pin on the Micro (bad soldering or dead micro)

Thanks for the advice dust, will do the swap tonight and let you know.

When I connect the printer, and switch on monitoring the hot end just reads room temp, it only goes spastic when the hot end temp is activated.

Thanks again