Possessed Printer

[sithslayer78]

So my printer has been having some strange issues lately (refusing to start a print, random heater decouples hours into prints, noisy and jagged temperature curves, etc.). I tried PID recalibration, messing with retraction settings, and the good 'ol power cycle. Anyway, I start a print last night and I come back to this:

[img]http://i.imgur.com/XJkjo9A.jpg?1[/img]

Not sure what happened, and I've been getting holes like in the side of the print for days now. (Don't mind the E3D Sock, that's still a HE280)

[img]http://i.imgur.com/E2cL1hX.png[/img]

And that's the smoothest my temperatures ever get while printing.

This printer's got 120+ days of printing on it, It's already lived past the UPS that it used to be powered off of, and I've burned at least one fuse on the RAMBO previously. So I suppose my question is this: Is it time to replace the RAMBO? or is there something else that could be causing all of these lovely issues?

[IMBoring25]

The noise, decouples, and some of the print quality issues will probably be because of an intermittent connection somewhere in one or both of the thermistor circuits. That needs to be fixed.

To opine on the printed part it would help to know what it was supposed to look like.

[sithslayer78]

To opine on the printed part it would help to know what it was supposed to look like.

Pretty much the same, Here's an image:
[img]http://i.imgur.com/SitRXEb.png[/img]

[Jimustanguitar]

Does that dip in temp between 21-26 minutes correspond with when your cooling fans came on?

[sithslayer78]

Does that dip in temp between 21-26 minutes correspond with when your cooling fans came on?

I doubt it, since it was over an hour into the print before it failed there.

[IMBoring25]

That dip happens too quickly to be a real dip. I'm still saying thermistor wiring problem, which can also produce the noisy region and the sudden jump back up over the setpoint when clean contact is restored.

[626Pilot]

Flaky thermistor (or connection) for sure, probably a shaky PID tune as well.

Easiest thing to try: replace your thermistor.

Second easiest thing to try: replace the wires and all connectors between the thermistor and your controller. You can lash some two-conductor wire to your existing cable harness if you don't want to redo the whole thing. In my experience, it's usually the wire somewhere near the connector that joins the hot end to the main harness. It gets moved around all the time. If you want to redo the entire harness, McMaster-Carr has really good robotics cable. I don't use anything else.

Once you're done troubleshooting, my PID tutorial will get your temperature curve as flat as a board.