Help fixing extruder wire on Davinci 1.0A

You need to buy one of this
https://www.amazon.com/BALITENSEN-Ceram … +cartridge

Loose the black hex screw in left of the heating element on your picture and put new one in. Tape the cable with kapton tape so that hot end movement will not break the wire in the future. Be careful not to break thermostat wire during the process and tape the thermostat wire too after finish.

I think you need JST 2.54 Housing and Female Pin Header Terminal Connector Kit. Something like this.
https://smile.amazon.com/460-PCS-Sets-2 … ST+housing

You can also use solder iron if you don't think you will need JST housing kits for the future.

I took out the nut that holds in the heater cable, but I can't slide out the old heater. How do you suggest I get the old one out?

+1 or if you have small punch or similar object, you could tap it from the other side with light taps from a hammer. Due to the heat they usually get seized. If you can get some anti-seize compound and put on the new one before you install it. It will smoke a bit but if you need to remove it at some point it should come out easily.

The material inside that heater core is ceramic. Making dust from that stuff and breathing it would not be a good idea. Plus is should come out just by twisting with pliers. The punch was a last resort. You may also need to get a heat gun and heat the hotend with it as it could be seized from melted filament.

So I did this fix some time ago and it all worked well.. for a while. Then one day after running the printer for hours on a print, I got the following error while using OctoPrint:
Error:One heater seems decoupled from thermistor - disabling all for safety!
When I switched to using Repetier, I got:
19:44:07.749 : DebugLevel:14
19:44:07.760 : Error:One heater seems decoupled from thermistor - disabling all for safety!
19:44:07.766 : Error:Temp. raised to slow. Rise = 0.93 after 31154 ms
19:44:07.773 : Disabling all heaters due to detected sensor defect.
19:44:07.775 : DebugLevel:14
19:44:10.411 : fatal:Heater/sensor failure Printer stopped and heaters disabled due to this error. Fix error and restart with M999.

So I replaced the heater cartridge and it worked fine for a few weeks, until I ran the printer for a day. Then I go the same error. Am I burning out the heater or is something else going on. If I turn the printer off for a day and retry, I get the same error.

Thanks Carl,
Do you know what thermister would work with a davinci 1.oa?

check your hotend wire harness first, it it known to be problematic for Da Vinci 1.0 and can cause the issue as Carl described. If you have unreliable wire harness, the issue shows up more frequently as your hotend moves and sometimes reboot printer fix it, but you want to take care of it for good.

Well I got a couple of prints, but have had the following error again several times. This is what I did/tried
I replaced the thermistor, but since I did not have the plug that goes into the hot end, I cut the wire to the old one and soldered the new thermistor into the old wire with the plug. So I guess it is possible the plug is faulty
That worked only for a short time
Then I tried heating up the hot end and bed and jiggled the wires around to see if one of them were faulty. I was not able to determine that, however in the course of doing that, I untied all of the wires and let them sit freely. This did let me get a 2 hr print in, however my next print failed after 30 mins. You guys mentioned the wire harness, do you have any pics of what you've done to fix that? Any other suggestions?

17:00:10.644 : Printing layer 5 of 60
17:01:41.396 : Printing layer 6 of 60
17:03:12.326 : Printing layer 7 of 60
17:04:48.377 : Printing layer 8 of 60
17:06:19.821 : Printing layer 9 of 60
17:07:44.386 : DebugLevel:14
17:07:44.397 : Error:One heater seems decoupled from thermistor - disabling all for safety!
17:07:44.405 : Error:Could not hold temperature 250.00 measured 231.70 deg. C
17:07:44.411 : Disabling all heaters due to detected sensor defect.
17:07:44.413 : DebugLevel:14
17:07:49.443 : fatal:Heater/sensor failure Printer stopped and heaters disabled due to this error. Fix error and restart with M999.
17:07:49.508 : fatal:Heater/sensor failure Printer stopped and heaters disabled due to this error. Fix error and restart with M999.

Carl,
Thank you for your help. I just want to clarify what you are suggesting, since I've rewired the head several things so far. On the left in yellow is my thermistor to the pcb, red on the left is the heater to the wire harness (is that what you call it?). Top left, red and black is to my fan and right is my pcb out to the harness. You are saying I should figure out which wires in the pcb to harness (on right) come from my thermistor and replace them? How do I figure out which ones are the correct wires from the pcb? I assume you've run into this problem. I guess my first shot would be to leave the connector and just solder in a new piece of wire. Did you end up replacing your connectors? if so, how did you figure out the correct connectors to order?

Chip