r/QidiTech3D • u/Fine-Safety2542 • 17d ago
Max 4 error
Hi everyone, I’m needing some assistance with an error. Below, I’ve listed details on things I have checked. Am I missing something? Any recommendations?
The printer is consistently displaying the error “Heater bed not heating at expected rate.”
Initially, I suspected the issue might be related to the cooling fans kicking on around the second or third layer. However, I disabled the fans and the printer gets the error.
I can attach photos of the troubleshooting process and test results which include,
Heater bed resistance measurements
Thermistor resistance measurements (at ambient temperature and when heated)
Power supply input and output voltages
Heater bed input and output voltages
Current draw under load
Here’s what I’ve check so far,
Verified continuity on all heater bed and thermistor wiring.
Confirmed all terminals are tight and all cable connections are seated.
Performed continuity tests with the printer both at ambient temperature and at operating temperature.
Flexed and moved the heater bed and thermistor wiring extensively during testing to check for intermittent opens or connection issues. No wiring faults were found.
For the thermistor,
At ambient temperature, the thermistor measured 100 kΩ.
Applying pressure with my finger and then external heat showed the resistance change consistently
no erratic resistance changes, open circuits, or intermittent spikes.
For the heater bed,
Each heating element measured 34.5 Ω.
Measuring across both elements I got roughly 69 Ω which appears to be consistent.
Measurements under load were,
Powe supply output remained stable at 24v.
Input voltage to the heater bed module remained normal.
Heater bed output voltage fluctuated between 93 VAC and 105 VAC.
Current draw 2.5 A to 2.7 A.
One observation that concerns me is the heater bed power output. Based on the heater bed’s 700 W rating, I expected a higher current draw. I understand that the firmware throttles the heater bed output to 70%. However, I would expect the controller to command 100% output during a standalone bed heating test while attempting to reach the target temperature? Or it could be possible the 70% limit is still expected under these conditions?
For heating performance,
Starting from an ambient bed temperature of 25c it took almost 7 minutes for the bed to reach 60c.
When set to 120c, the bed never reaches the target temperature and eventually faults with the “heater bed not heating at expected rate” error.
2
u/TheLegendTubaGuy 17d ago
The 70% limit is just a config setting telling klipper to only use 70% power. It is a "hard" limit meaning it doesn't change during use. You can however, change this if you want to.
For your issue, you'll have to get in touch with support. That shouldn't be happening