SOLVED Print Core Wiring

[LouisvV 0]

One of my prints came unstuck during printing and the failure caused the material to build up around the hotend. It was quite a job to get the material off of the print head and in the process I have pulled out the heater and sensor wiring from the print core chip. I have tried re-wiring it myself by comparing the pattern to other print cores I have but when I came to use it the hot end went up to around 350 degrees before ending in an error. 

 

Is there a wiring diagram of the print cores anywhere or are there any other issues I should be looking at when reinserting the wires back into the chip?

[gr5 2,170]

You may have damaged your electronics inside the print head.

 

You wired it up properly otherwise it either would not heat up or it would not read back a temperature.

 

What you did wrong is you created a short somehow.  There are 5 contacts - there are 4+3+2+1 or 10 possible shorts.  Check every combination.  The left two pads should be the heater so around 25 ohms.  The right two pads should be the sensor so around 109 ohms at room temperature.  ALL other combinations should show as an open (certainly > 200 ohms).  The short would have to be less than 5 ohms to cause the heater to not stop heating up.

 

MOST likely location for the short is between where the right hand heater wire is right next to the left hand sensor wire.  There's probably a tiny tiny strand of wire bridging the gap there.

[LouisvV 0]

You were right!

 

The fabric conduit around the outside had frayed down a bit and the two wires were contacting down near the plastic so it wasn't easy to see.

 

Thanks for the help and hopefully it will keep working well! I may have tidy up the wires a bit to stop it happening again.

[gr5 2,170]

Cut off any wires that aren't behaving. Or twist them together and add a little bit of solder to hold them together.

[gr5 2,170]

I just hope you didn't damage any of the circuit boards in your printer - either the one in the print head or the "marlin" one underneath.

[LouisvV 0]

I hope so too but so far, so good.