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If I set the temperature of my hotend with pronterface to 200 °C, the temperature never reaches that value. For instance, it almost reaches the target with a temperate of 196/197 °C and then starts to drop to 184/85 °C before it starts to rise again to 196/197 °C. It remains in this loop forever and thus I'm not able to start any print because the temperature never stabilizes enough.

I've tried to configure the PID (M303 E0 S200 C8) with 8, 12, 15 intervals not help the issue continue.

I've tried to change heatblock and thermistor not help

Its important to refer this behaviour occur in any tempurate if I fix 150º it never reaches 150º it go to 146/147º and then drops again 10/15º and restart the loop. Same thing if I fix the tempurature to 210º.

Also I've tested this in multiple versions of marlin 1.1.8 and 1.1.9.The version of marlin 1.1.8 have worked in the same print in the past.

I'm have not clue about what can cause this issue, maybe its a board malfunctions (mosfet) or a powersupply malfunction.

Somebody can help me on this?

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  • $\begingroup$ Did you change the Heater Block (square metal block) or the Heater Cartrige (the actual heating element)? What is your Printer? What kind of hotend you use? Did you save your settings after PID tuning? $\endgroup$ – Trish Dec 20 '18 at 12:06
  • $\begingroup$ Can you go higher than 200 °C when you set the temperature to 235 °C for instance? $\endgroup$ – 0scar♦ Dec 20 '18 at 14:06
  • $\begingroup$ Yes my printer could reaches higher temp then 200º easy. I've a heat cartrige of 50w the problem is stabilize that temp. I'm using 3dv6 clone with Trianglelab Thermistor Cartridge 260 from ali $\endgroup$ – mastervv Dec 20 '18 at 16:24
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Your description sounds indeed as if the PID is not correct. You can try autotune with M303 only if your heating cartridge is not absolutely overpowered. However, in such a case you typically also have an overshoot, which you don't mention in your description.

In that case you need to lower your duty cycle (by the BANG_MAX parameter in the firmware) a bit. Otherwise autotune fails, because your heating cartridge overshoots even at small gains.

Out of the box I would suggest you to increase your D-term and decrease your I term if it cycles like that. For most printers, I used, a ratio like that is sufficient: 4/1.5/25.

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  • $\begingroup$ Many thanks for your reply I not mention but have update my termistor (Trianglelab Thermistor Cartridge 260) and heat Cartrige to a new 50w aswell as the heat block. How I can check if the PID routine was failed? Because I'm using the value that came out of that routine. $\endgroup$ – mastervv Dec 20 '18 at 16:23
  • $\begingroup$ When heating up, do you have overshoots? Typically, in such cases and after Autotune you will just get PIDs leading to overshoot-undershoot-loops which indicate that the D-Term is too low. At least it was like this for me. Just set your Bang_MAX to 64 and try again. $\endgroup$ – dgrat Dec 20 '18 at 16:41
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    $\begingroup$ During autotune PID I'm seeing overshoots, tempurature raise over the setted temperature. But in print's never get overshots only undershoots. In case never have overshoots should I increase or decrease D-Term in PID parameters?? I'll set my bang_max to 64 now its setted 255. I'll drecrease $\endgroup$ – mastervv Dec 20 '18 at 17:33
  • $\begingroup$ your tip have solve my issue I reduce the BANG_MAX from 255 to 240 and them I've run the M303 whiout any parameters that have run the PID with round temp of 160 and gave me parameters which work for me. Many thanks for your help $\endgroup$ – mastervv Dec 21 '18 at 11:11

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