YIKES! Rapid Temperature Runaway Upon connecting to Host Program

Good Day All,

My original RepRap Pro Huxley setup (644 Melzi Board) has a horrifying affliction.

Sometimes, not always, upon connecting to a host program (such as Repetier) the hotend will rapidly build temperature to dangerous levels.

This is completely without input. The host program will even display the absence of a set temperature; but the temp will sky rocket.

I am not sure what is causing this. A weak or damaged mosfet? The problem is certainly intermittent, and has occurred with different extruder and hot end configurations.

I appreciate you thoughts...

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FabberForge - Printing Happiness

[www.fabberforge.com]

That is strange. But de-soldering one of those MOSFETS is going to SUCK...unless you have a hotair rework station handy.

The next time it does this meter out the gate to see if it's getting 5V. If it is then it isn't the MOSFET...something else.

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- akhlut

Just remember - Iterate, Iterate, Iterate!

[myhomelessmind.blogspot.com]

... desoldering even SMT-chips with many pins is relative easy when pushing a thin Nickel-foil (e.g. the small stripes out from the common anti-theft radio-labels) under the pin while the solder is fluid ...

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Viktor
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Solder-wick usually makes short work of the pins for me. I just don't know if he has any on hand.

It's that heatsink soldered to the pad beneath that might be troublesome - doesn't seem like there is a whole lot of "meat" there to get an iron on.

But then again it might just pop off once the pins are de-soldered.

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- akhlut

Just remember - Iterate, Iterate, Iterate!

[myhomelessmind.blogspot.com]

I had this on a RAMBo in my M2 Mosaic. never figured it out, and was within the first few prints (bigfoot!) of unboxing it.

Noticed and smelled it.
Saw the temp on Printrun at 320 while only trying to achieve 195.

Powered everything down just as the brass tip was drooping out of the PEEK.
Prop'd it up while it cooled, then reset the Z, because it did get longer.

Been fine ever since and my trust for leaving it unattended is slowing building up.

Dave