Random heater failure - dual extrusion

[snowygrouch 1]

I have problems with dual extrusion prints failing. The main extruder motor

just stops getting signal from the board at random points in the Z level. (I mean it is not trying to turn, this is not a plugging issue).

Wherafter it will not start again in the same print.

This is traced to the same hotend just randomly cooling down. So the Ulticontroller shows that it knows that T0 is supposed to be 210 deg...but it shows the temp cooling

down to ambient anyway. So at this point I guess the firmware safety

stops the extruder going because it knows it cannot print.

So the unticontroller screen will read something good at the start for T0 and T1 temps like

209/210 208/210

Then at a random point (same gcode !) in Z level (like 4mm or 7.5mm up etc)

It will just go to something like:

190/210 208/210

170/210 208/210

150/210 208/210

..... 208/210

50/210 208/210

etc

Weird...as it clearly knows its supposed to be heating both of them...but doesnt or cannot sucessfully heat T0....I check the very basic stuff like all wires screwed

in and so on, but dont want to do a full electronics stripdown without feedback.

Ideas ?

C.

 

[gr5 2,210]

Well it's obvious to me at least that there is nothing wrong with your temp sensor but something wrong with your heater cable. This is easier to debug and trace than temp sensor. When it starts drifting down, check the voltage under the UM to see if the relay is broken or if it's the wiring. Also jiggle the wiring under the board and along the path to the nozzle heater.

 

[snowygrouch 1]

Yep I just swapped the heater connections on the main board, and the controller quite

happily heats up the #2 heater cartridge - so the board is ok.

The TC`s on both hotends are also fine.

I dont know much about typical failure modes of heater cartridges, if this can be caused by

the board giving voltage spikes or switching on/off too frequently or suchlike.

But looks like just a failed heater cartridge. Just strange to me that it "kind of" worked for

a fair while then just stopped. When it did work it was totally ok...then just BAM...off.

I suppose I will have to order a new one at some unbelievable price :shock: and try it again....

I did have to jiggle the wiring around alot when I installed the 2nd hotend. Perhaps it was

all too much for the heater cartridge wiring...

C.

EDIT:

Yep thought so....32 Euros PLUS tax....for a 40w 18V heater unit....similar

parts typically being sold everywhere else for about 400% less than that.

HELLO UMAKER !!!! NO FRIENDS ARE MADE BY SHAMELESS MARKUPS

Anyone sucessfully using an alternative for these ?

 

[calinb 11]

Hmm...I've done some testing of a hot end that has only a sightly more powerful heater (lower resistance) than the UM cartridge heater and my power supply/drivers could not power it reliably. (I had to reduce PID_MAX in Configuration.h to use the hot end.) Here's the line:

#define PID_MAX 256 // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 256=full current

Can you confirm that, in running each heater singly and alone (as in single extrusion mode), one of the heaters behaved faultily?

Weird...as it clearly knows its supposed to be heating both of them...but doesnt or cannot sucessfully heat T0....I check the very basic stuff like all wires screwed

in and so on, but dont want to do a full electronics stripdown without feedback.

Ideas ?

C.