I’ve just finished assembling a K8400 and ran into a problem with the printhead. Effectively with everything wired up I get a ERR:MAXTEMP message. Mechanically everything is fine, steppers are working, homing and manual positioning works fine and I’ve updated to the 1.4 single head firmware (using the old Arduino 1.0.6 as described).
To narrow it down I did some small tests, maybe this helps identifying the faulty bits:
Printhead connector disconnected:
Status shows 0/0° for the PH plus “ERR:MINTEMP” on the bottom line
PH connector plugged into PH PCB, Temp sensor and heating element disconnected from PH PCB
“109/0°” and “Vertex is ready”
as above with Temp sensor connected to MIDDLE terminal block
Same reading as above: “109/0°” and “Vertex is ready” . I measured the resistance of the temp sensor on its own (~100kOhm) and also across the terminal (also ~100kOhm)
as soon as I attach the heating element to the left terminal block the reading goes to “ERR:MAXTEMP”
I’ve also looked whether there is some solder bridges as I’ve read in another thread in this forum but couldn’t finde anything.
Does this description make any sense so far or are there other things I can try and test?
In point 2 with the thermistor disconnected you should get the same reading as in point 1. Moreover 109° isn’t a correct value. So it seems the problem lies on the U shaped PH PCB. Try disconnecting the PH connector and measure the resistance at the thermistor terminal.
In point 2 with the thermistor disconnected you should get the same reading as in point 1. Moreover 109° isn’t a correct value. So it seems the problem lies on the U shaped PH PCB.[/quote]
Thanks, that’s what I’m thinking as well. Could it also be a faulty wiring loom? Mismatched pins or something like this?
I just did that: The reading stays the same (I don’t trust the values of the Multimeter though) whether I measure across the terminal or the element alone. I also measured across the terminal with the temp sensor disconnected to see whether there’s a shortcut or something but there the reading stays at infinite.
I guess I have to disassemble the PH now and see whether I did a mistake or whether there’s a visible fault on the PCB.
That is definetly not an issue. I took the sensor and the heating element out of the PH and measured them that way to be sure.
The thermistor also reacts to temperature, I can see the display changing on the Multimeter when I touch the sensor.
How much restistance should the heater cartridge have? What I measure with the Multimeter (cheap one so I don’t trust the absolute values but it should be enough to distinguish the “region” so to say) and on my heater I’d say the restistance is very low.