Thermistor reading error

Hey all,

Getting the dreaded “-15” hot end temp. Tried spare hotend with its own thermistor, spare keyplate, spare ribbon cable and same result. Melzi was literally just replaced before i flashed to 4.0.4. Any ideas?

Edit: should add, parts were all genuine stock from cocoon

-15 means that the firmware is receiving 0 in its input (or close). You can check this on Tuning / Diagnosis. The value under PF1 (in red) should be 0 or near 0. If the value change a bit, it means that, probably, there is some cut somewhere.

The printer does not have a Melzi board. It is a custom board made by Wanhao.

Still replaced with wanhao branded part from cocoon.

Edit: and now E-motor issues. Argbbllee. Gonna call it a night. The gods have spoken.

Have you look at the small PCB behind the printer? Maybe the cable is loose, or this board has a problem.

The interface keyplate for the E-motor, thermistor, hot end heater and fans? Yup, first thing i checked - i’d actually blown one previously being a jackass replacing a gummed up hotend while it was live, so i had spares (couldn’t get in Australia, had to order from the US so i doubled up :slight_smile: )

Also i’m an idiot, the -15 thermistor was bed, not hotend, so i’ll have a look at that tomorrow as it’s most likely cabling (got spares). Still aggravated with the e-motor though. If i run it to load, it kicks in for a second, then stops. Motor runs fine on Z controller though. This was actually the cause of the re-kit - put in a flexion, then decided to toss in a new nema since i was having extrusion issues I couldn’t resolve with calibration and kill two birds with one stone. Got rocking behaviour on the new motor, then stopped, then the old one no longer worked so i thought i’d blown something again (although still not sure how). Went through everything part by part right up to the entire mainboard…which meant i had to reflash as the new board was definitely not the same firmware as the LCD. Been a conga line of aggravations tonight!


So it is not the interface PCB behind the printer.

It is very difficult to follow what you are doing.


Installed a new flexion and motor. New motor would not run right, stuttering issues to non-movement. Went back to original stock motor, that one exhibited same issue. Ran the gamut from testing the motor on a z axis controllers / swapping out cables, swapping out keyplate, finally replacing board - at which point the clash between the flashed LCD and non-flashed new mainboard made the touch screen have issues, and since i was running an older ADV++ anyway, I flashed the whole lot up to 4.04. That’s when i noticed the thermistor error in the subject line (tentatively resolved, i’ll plug another in tomorrow to test) and the motor is still being an asshat.

Hope that makes sense, it’s nearly 3am here.

Before that, was the printer working? And with which firmware?

Yes, and 3.0.3.

Ok, running a HOME command ignored the Z stop, then read a thermal error when the switch is down, time to crack the case and check the board, they may have sent me a differing version to the original '17 stock. (Definitely have not confused board thermistor and Z stop, i have a very distinctive cable on the former)

Apparently yes, i am that daft. Fixed. Working on e motor now, should this have its own topic?

You sound like an Aussie, and I hope that you can sort out the problems with your printer. I don’t have any technical benefit to add to your problem or solution, sorry, but given your predicament, I’d love to watch a live stream of you stuffing around with it. Would be bloody hilarious.

I promise i’m actually a lot more proficient than it looks, yesterday just ran a train on me :stuck_out_tongue:

Lockdown must be causing brain damage.

@ian.taylor4 Not sure it is the right place to make such comments. I prefer if you don’t.