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... https://reprap.org/forum/read.php?1,182678,182678#msg-182678 Tue, 08 Sep 2026 17:04:09 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?1,182678,182906#msg-182906 https://reprap.org/forum/read.php?1,182678,182906#msg-182906
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]]> davew_tx General Thu, 07 Feb 2013 18:28:09 -0500 https://reprap.org/forum/read.php?1,182678,182776#msg-182776 https://reprap.org/forum/read.php?1,182678,182776#msg-182776
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.]]> akhlut General Thu, 07 Feb 2013 10:47:32 -0500 https://reprap.org/forum/read.php?1,182678,182771#msg-182771 https://reprap.org/forum/read.php?1,182678,182771#msg-182771 VDX General Thu, 07 Feb 2013 10:27:40 -0500 https://reprap.org/forum/read.php?1,182678,182761#msg-182761 https://reprap.org/forum/read.php?1,182678,182761#msg-182761
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.]]> akhlut General Thu, 07 Feb 2013 09:44:39 -0500 https://reprap.org/forum/read.php?1,182678,182678#msg-182678 https://reprap.org/forum/read.php?1,182678,182678#msg-182678
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...]]> Idolcrasher General Wed, 06 Feb 2013 23:53:42 -0500