I have found out that the HUB motor will not allow the filament to enter the extruder from any of the ports.
I removed the power cable and then re-inserted it and the system came alive.
I was able to print one more project.
Has someone come across this before?
Iām having the same problem.
Had all 4 feeders fail within 3 weeks of each other. got them replaced and bought a new main board to go with them just incase. The old board was faulty too so it was a good decision. However on the new board i get all 4 feeders flash the double red lights. Device tab in Bambu studio shows No AMS.
All cables are connected tightly
Maybe try replacing cables?
I bought the cable replacement kit that was supposed to contain a 485 ( comms cable ) but it didnāt have one
Contact Bambu, when arenāt backed up with 1000ās of orders their customer service is actually quite great. Also what about external cables, is it possible one of them has been damaged? If the problem cannot be fixed Bambu may send you a new AMS.
Sadly enough it started again. Checked all connections. No luck. Every time it happens with pulling back filament. The device shows that suddenly the exeternal spool is used and filament couldānt be pulled back. But the external spool is not used. It was pulling back ASA filament from a print that was just done. I tried to load filament to the tube, let it purge and see that it was done. Then follow the messages on the display to pull out the filament again. But it didnt resolve the issue. On the devise tab it still shows that the exteral filament spool is used and there are no spools in the AMS show on the display. Teddy, are you able to assist? 
Just now I disconnected the AMS and let the X1C perform a device self-test. When the test was done I connected the AMS again, the spools where recorgnised (it read all the NFCās of the spools again) and the error was resolved. Dontās know how and why this happens. For now it seems resolved. Lets hope it stayes that way.
The same problem occurred with my two AMS units, all flashing red. Using the diagnostic instructions provided by Bambu Labs, I tested sig-A and Sig-Bās resistance to each other and to ground, then sent the results to Bambu Labs. I had to replace the motherboard and communication board on each AMS. My hub tested ok. After replacing the components everything worked as expected.
Just had the same problem with the red blinking lights on the AMS. Funny thing is that they will do this sometimes in the middle of a print and still print. I changed the Bus cable, the power boardā¦and it was fine and then in the middle of a print again, all the lights started blinking. I may try to replace the cables next.
No way. This actually fixed it for me. thanks for posting this!
I have been messing with this issue for a couple months and although I feel like an idiot after finding the solution I thought Id hop on here in case someone is dealing with the same. After orderinga new 6 pin communicatio cable for my AMS I have no realized that the cable is single direction. Meaning one end of the Cable has a label āCā which must be connected to the AMS for proper communication, if you have it backwards you will get the four flashing red LEDS. SO there you go. try reversing taht cable before you tear your printer apart.
I just updated my firmware on my Bambu Carbon X-1 and now the AMS is all blinking redā¦ thus how I found your post. Iām not sure where to begin as I am a newbie. Iāve turned everything off and on and it will not let me remove 2 of the filaments. I will be trying to go through each thing but I am not comfortable taking my machine apart. Ugh.
I just went through a bout with red blinking lights again. It was the connectors on the back of the printer. One for the hub and the other one connecting to the AMS. Reseated the connectors, the AMS did fine for a week before it did it again.
I bought this stuff.
A little dab will do ya. Its been fine now for three weeks. 
Time will tell.
Update: I just plugged the back into the other AMS slot and everthing went back to normal. I eventually reset everything and moved back to the first slot and working fine. Thanks for the help.
Iāve had this issue, intermittently, for the last few months. I noticed if I print anything thatās not PLA, I get the red blinking lights on all 4 AMS units. My thought is, my 110v 15amp circuit may be pushed too far for my 2 X1Cs and all their AMS units (6 in total) to print higher temp materials, at least at the same time. I have my H2D and 2 AMS and HTs on a dedicated 20amp circuit, and no issues thus far.
I asked ChatGPT for the info below, so grain of salt, but Iām sure itās not far off. If I kick off 2 prints simultaneously, with say ABS for both, my theoretical max amperage draw could be around 9.5amps each for bed heating during startup.
Iāve never tripped the breaker, so this conjecture might be misguided.
Total Amperage at 110V (US standard voltage)
Total Estimated Amperage
| Scenario | Total Amps (approx) |
|---|---|
| Typical Load | 2.3 A + 0.18 A ā 2.5 A |
| Peak Load | 9.1 A + 0.36 A ā 9.5 A |
So before you changed the Power Board you had power and red flashing lights? Even though the Power Board was bad? I am just asking because when I was working on my AMS a while back I actually heard an electrical arc sound when I was plugging in the connectors to the power board and thats when the red flashing lights started. I changed the Main Board thinking it had to be that since I had power but red lights. So i just went ahead and ordered the new Power Board a few days ago and I am waiting for it to deliver but wanted to do a little digging while i wait. I think we have the same issue but wondering if you still had power but the board was bad!! Thanks
I would say that the power board was good. The connectors on the power board were dodgy. So i used dielectric grease to make a better connection electrically.
This dielectric grease has stopped my red blinking light problem.
Hpe this helps.
TL;DR: Wiggled stuff inside printer, accidentally fixed the issue. Not confident itās fully resolved, but it has completed a few dozen filament swaps successfully now.
Printer: X1C
Print hours when symptoms appeared: ~1500
Length of time problem was ignored: 6+ months
Did problem resolve itself: no
Symptoms: Print starts fine using filament from AMS and may change filaments 1-2 times, but four flashing lights appear regularly during a print job. Turning printer off/on usually, though not always, returns the AMS to a temporarily-working state. If using only one color, print usually (est 80+%) completes successfully even if connection with AMS is lost.
Preliminary troubleshooting steps taken:
1.) Applied DeoxIT D100L from bottle to 4-pin and 6-pin connectors on the back of the printer, buffer, and AMS.
2.) Replaced 6-pin cable after step 1 did not remedy issue
Result: Initial improvement likely placebo, issue remains
Story:
It got to the point where not being able to use support material was holding up a few projects and I needed to finally address this issue. I followed the troubleshooting guide (Linked above by mfetting. Iām unable to include links for some reason) and found that the resistance for GND-sigA and sigA-sigB were in spec, but GND-sigB was ~5.37 k-ohms on the port on the AMS and ~5.95 k-ohms on the port on the printer. I opened up the AMS and determined it was the AMS main board that was out of spec, rather than the AMS power board.
Not keen on throwing parts at it without understanding the root cause, I didnāt feel confident that the measurements were far enough out of spec to cause these issues and talked to one of the EEs at work. He said it was probably fine, and after describing the symptoms, suggested it was likely something in the connection chain, given the intermittent nature and how the issue somehow resolves itself by power cycling the printer. He suggested hitting the contacts on the board with a soldering iron to re-flow the solder, that it could be a cracked solder joint that wasnāt visible.
When I got home the red lights were flashing on the AMS, so I started wiggling the external connectors, starting at the AMS. When I got to the 4-pin going into the printer, the lights changed from red to white. Interesting.
I turned the printer off, took the back off, noted the connections on the two boards looked fully seated, took one of the spare 4 pin cables I had and cut it in half, stripped the wires and tinned the ends. I plugged it back into the port on the back of the printer and connected alligator clips to the wires. GND-sigB was open at that point, so I started methodically wiggling the external 4-pin plug, and the other two in the printer on the AMS interface board and the MC (machine controller) board.
I thought I had a pattern figured out of what made resistance go up and what made it go down, but nothing was really repeatable and eventually I couldnāt make it go up at all, it was solid at 4.34 k-ohms, unless I fully unplugged a connector, right in the expected range from 4-5 k-ohms. I left the back off so it was easy to access again and started a print with about 50 filament swaps and it ran all night without issue (aside from the usual issues with the spool being too light and causing feeding issues).
Conclusion:
Wiggling the connections on the printer side of the connection chain appears to have brought the resistance reading into spec. Iām not confident that the issue is fully resolved but itās of some comfort that my issue is likely a connection issue rather than a dead board. The printer so far has completed a few dozen filament changes, which is a few dozen-1 more than pre-wiggling.
Thanks to those who shared their experiences previously, some were helpful. Hope this helps someone else.
Picture from mid-wiggling session before resistance value had stabilized. I switched to alligator clips as I wasnāt certain the leads pictured werenāt contributing to the fluctuating readings.
checking / replugging all the connections worked for me (think it was one of the ones inside the ams itself).
