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MK4S high flow nozzle and lack of power  

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Krulle
(@krulle)
Member
MK4S high flow nozzle and lack of power

Hi,
yesterday I converted my MK4 to the MK4S and encountered the problem that the self-test for the heating of the nozzle fails and when ignoring it, the error #26204 (thermal runaway) occurred when printing (after approx. 1:30h).

I did some research and came across the parameters for the test in the source code: The nozzle must be heated from 80 °C to at least 195 °C within 42 seconds (20 °C less with a silicone sock) and my printer doesn't manage that. Without the sock it reaches ~190 °C after 42 seconds and with the sock just 162 °C. I suspect that the heating power is not sufficient here and that the temperature has dropped too much during printing due to the conversion to the high-flow nozzle.

After today's tests, I can confirm this: With the normal nozzle the PWM is ~70-80%, with the high-flow nozzle it rises to 100% with long movements and the temperature drops from 235 to 229/230 °C.

Is this a fault in the design or is there something wrong with my heating cartridge? Has anyone had similar experiences?
The printer has currently been running for ~408 hours.

(The fact that the housing of the LCD does not harmonize with enclosure is currently just another step in my pissed-offness. What the hell they doing?)

This topic was modified 1 month ago by Krulle
Posted : 10/11/2024 9:27 am
Volker
(@volker)
Estimable Member
RE: MK4S high flow nozzle and lack of power

I made a similar experience: without the silicon sock the print stops after a certain time with "thermistor error". The nozzle temperature dropps.
Since then I print with the silicon sock. Another option would be to reduce the max. volumetric flow - but thats against the purpose of the high flow nozzle. Maybe the regulation parameter will be adjusted with a firmware. But most likely the electrical power of the heater is not sufficient.

Posted : 14/11/2024 6:00 am
Pepan
(@pepan-3)
Eminent Member
RE:

Did you changed settings of printer (with sock / without sock) when you used the sock? Heating test failure should not have anything to do MK4S upgrade. Heater block is the same, heater is same and thermistor is in heater block. Maybe when you changed the nozzle, didnt you move (or damage it / wires) with thermistor or heater?

This post was modified 2 weeks ago 2 times by Pepan
Posted : 27/11/2024 11:32 am
Volker
(@volker)
Estimable Member
RE: MK4S high flow nozzle and lack of power

It's simple a put on/off test. With silicon sock no problem; without thermistor failure once the high speed (infill) has started.

Posted : 27/11/2024 6:27 pm
Krulle
(@krulle)
Member
Topic starter answered:
RE:

If you jump over the same issue, test resistance of thermistor and heaters: https://help.prusa3d.com/article/multimeter-usage_2117

My problem was the heater and his resistance (16.8 ohm) was too high. As a result the heat output was no longer sufficient. Support sent me a new heater and the problem was solved.

Posted : 27/11/2024 6:36 pm
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