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Jul 2016

At this point I think testing the current going to both hot ends is needed to pin down whether correct wattage is present. Since you have the necessary 24 volts the next step is the current. If something in the heating circuit is defective you should be able to to see it when testing both the voltage and current. Since the voltage is fine the next step is checking the current. Try putting an amp meter in series with the wire connected to the hot end. Most voltmeters these days have a setting for testing the amperage. You should set it to 10 amps for testing I am just worried that the current going to the hot end is higher than 10 amps and you burn out your amp meter. If anyone else has the specs to ensure he doesn’t burn his amp meter please chime in.

Both have the same current in and out,

However the left nozzle that can heat to a higher temperature uses 1.39 at first then declines to 1.34 and then when its 5C from the target temp then fluctuates 1.00-1.32 and the right one uses 1.43 all the way, do you think the heating cartridges are not accepting what power they need?

After thinking about it, if both are pulling the same current, and one gets hotter, it has to be a heat sinking problem. The law of conservation of energy says the energy has to go somewhere, and it apparently isn’t staying in the hot end of the setup, unless the thermistor is lying.

You know what you have a point. Don’t know why I overlooked that fact. It is getting slightly more current than the left extruder so it should be getting just as hot as the left assuming nothing of the right extruder is different than the left. In that case a faulty thermistor which gives an incorrect reading would definitely lead to this issue. The only way to verify this is to switch both thermistors and put the right thermistor in the left hot end and the left one in the right hot end. Good catch Ed!

Also, I think your motherboard can not handle it. I think you should shut of the right nozzle, To make sure and try to give the left nozzle all the attention.

I’d agree with this except that when he tested both the voltage and current to both nozzles. The right nozzle ( the one that doesn’t achieve the desired temperature) does get the same voltage but more current. So in theory it should be hotter than the left nozzle. The running idea is that the thermocouple is not telling the truth for the right extruder. it seems that is causing the heating element to continually use the same current as if it was heating from cold start. The only way we can check is to swap thermocouples from left to right and right to left to see if the problem goes away in the right extruder but presents itself in the left. If that’s the case then we identified the problem to be the thermocouple.

I just realised you replied to my post about the upgraded 80w hot end. In that case if you were talking about the upgraded hot ends not working with the motherboard then I agree with that statement and you can disregard my last reply.

I would try swapping thermocouples and plugs at the PCB to see if the problem follows to the other side while heating, that way you know if it’s a faulty thermocouple or not.

Likely, you have broken your heater cartridge when doing the replacement. They have very tiny wires, and are very delicate.

If the same current and voltage is flowing into both heaters and one is hotter, either the themocouple lies, OR the heat is going somewhere it shouldn’t.

The thermocouple would lie if:

  1. It is defective.
  2. It isn’t attached to the aluminum block with thermal integrity.
  3. The wiring is faulty.
  4. The A-D converter in the microprocessor is faulty (not likely)
  5. The firmware interprets the reading incorrectly (not likely)

The heat would be going somewhere if:

  1. There is too much heat conductivity from the hot end through the tube to the feeder block (across the thermal barrier built into the tube).
  2. Too much cool air across the hotend from a fan.
  3. Operation in very cold conditions (not possible for only one of two extruders).

Swapping components is a good way to troubleshoot.

I agree with you on that one. Try swapping the sensors to test them and you should see if the problem moves to the left hot end after the swap.

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Mini Wang-Flashforge

1) Improve the installation method of the extruder to have better temperature protection. Because if the extruder is cooled down by the fan, the power will be waste. So, if the temperature is well reserved, 40W is strong enough;

2) If above method does not workable for you. We suggest you change a power supply with larger power, say 400W, then you can have a 80W cartridge heater. Because our current power supply is about 320W, if all electronic components work at the same time, the power supply may not able provide enough power.

Hope this helps. Thank you.