¶ Issue Description
HMS_0700_4000_0002_0001：%0 %1 Filament buffer position signal lost: the cable or position sensor may be malfunctioning.
When using AMS, the buffer (or AMS hub) is connected between the AMS and the printer.
It has two sliders, two springs, and four Hall sensors. When the AMS pushes the filament into the extruder, the slider will move forward due to the pressure of the filament. Then, the first Hall sensor at the entrance detects whether the filament enters the buffer, and the Hall sensor above the second slider can detect the displacement and position of the slider and feed the signal back to the AMS and the printer. If the buffer signal is lost, the AMS will not be able to load the filament smoothly.
¶ Troubleshooting
¶ Check the 6-pin cable
Check whether the cable is in good contact with the AMS tail and whether it can be easily pulled out by hand. It is recommended to use the new 6-pin cable. The cable differences are as follows:
¶ Check and reconnect the 6-pin cable
Please check whether the pins of the 6-pin cable are open:
And try to reconnect the 6-pin cable:
¶ Check the internal connection of AMS
If the problem still exists, please refer to the following steps to check whether the AMS signal cable is loose:
- Press the PTFE tube release button from the back of AMS to unlock the connector and pull out the tube;
- After pinching the buckle from the inside of the lower cover to automatically pop open the PTFE tube release button, pull out the PTFE tube release button from the back;
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When pinching the buckle, use your other hand to hold the PTFE tube release button from the back of the AMS to prevent the spring from being ejected and lost.
- Remove the driven support sleeve assembly of the two middle slots to expose the two screw holes. When removing the bearing sleeve, be careful with the bearings at both ends to avoid losing them.
- Remove the two screws A that secure the AMS main frame.
- Lift the rear part of the main frame completely and place it vertically on the lower cover of the AMS. Note that there are cables connected, so do not operate violently. When lifting, it is recommended to lift the front part of the main frame first, and then push it forward to make room for the rear part of the frame.
When placing the AMS main frame vertically, avoid the electronic components of the vent to prevent them from being crushed.
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- Check whether the signal cable is properly inserted. If not, re-insert it tightly. Then disconnect the signal cable and power cable and lift out the main frame.
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- Check whether the signal cable on the mainboard is firmly plugged in. If not, plug it in again.
¶ Measure voltage and resistance
- If you have a multimeter, unload the filament to AMS, identify the channel to be measured (H2D right nozzle is the upper coupler, left nozzle is the lower upper coupler), and check that the slider of the AMS buffer is on the left, as shown below:
Then measure the voltage between the pins of the 6-pin cable (unplugged from the AMS).
Normal voltage should be as follows. Make sure the buffer slider is back to the left, otherwise the voltage value will be different.
| pin-pin | Voltage |
| GND-Buffe_A | 0.5~1.0V |
| GND-Buffe_B | 2.8~2.3V |
The sum of the two voltages is 3.0~3.3V (you can slide the slider to measure the voltage at different positions and add them within this range).
- If the measured voltage is within the normal range, the problem may be on the AMS side. Please measure the resistance of the 6-pin cable (plugged into the AMS). The normal resistance value is as follows:
| pin-pin | Resistance |
| GND-Buffe_A | 4~6 KΩ |
| GND-Buffe_B | 4~6 KΩ |
If the measured resistance value is abnormal, please disassemble the AMS and measure the resistance of buffers A and B to GND on the AMS mainboard. The normal range is 4~6KΩ. If the resistance value is abnormal, the AMS mainboard is faulty.
¶ End Notes
We hope the detailed guide provided has been helpful and informative.
If this guide does not solve your problem, please submit a technical ticket, we will answer your questions and provide assistance.
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