A1 + AMS Lite Communication Issue - Can't Figure It Out

[Trident_Productions]

A1 printer on 01.07.02.00 firmware
AMS Lite Flashing 4 red LEDs

I have had this printer since ~Xmas 2024 and have printed probably hundreds of things in that time, without any real issue.

However, about 2 weeks ago, I had just completed a print and was going to start a new one. I get to the point where I am going to send the print to the printer, and it fails. I noticed the LEDs on my AMS lite had begun flashing all 4 red. In doing the basic troubleshooting, I’d gone to reseat the AMS cable and found the plastic sheathes covering the pins on the cable had been damaged, and the pins were bent. I gently bent them back into place (using the plastic sheath bit that was still in place so as to not actually touch the pins) and tried to reseat them gently. No dice, so I purchase a new cable from Bambu and swapped it out yesterday using the tutorial here. Easy enough to do, and I reassembled the AMS without much fuss. Plugged it back into the printer and powered on. AMS lights up Spool 1, 2, 3, 4, then solid white on all 4 spools. I think I’m home free and then after about 5 seconds, I get the red flashing on all 4 spools. Video of the lights immediately after power on hosted over here.

I’ve already taken the AMS board out of the base of the printer, made sure there were no damaged pins and put it back in.

Rebooted countless times. Even dropped down to firmware 01.03.00.00 to see if that made any difference. The issue persists, and I am losing my mind trying to figure out what the issue is, as I really don’t want to keep buying parts or just straight up replace it.

I haven’t tested with an actual print just yet, but it appear the printer will function fine using the external spool, so I am leaning towards something with the AMS itself. Anyone have any ideas?

[Shadows]

Hello!

Let me know if these are your problems.

• Loose or partially seated communication cable (often USB-C underneath the printer), which carries sensor data from the AMS.

• Firmware or Bambu Studio version mismatch, where certain versions incorrectly sync AMS assignments or expect an external spool.

• PTFE routing or tight filament path, which causes the feeder motor to fail during loading and produces feed or communication errors.

• Slot-specific feeder or sensor problems inside the AMS Lite, where one spool position repeatedly fails during multi-colour prints.

I hope this can get resolved quickly.

Cheers,

[Trident_Productions]

@Shadows

• Loose or partially seated communication cable (often USB-C underneath the printer), which carries sensor data from the AMS.
  • All cables have been disconnected and reconnected.
• Firmware or Bambu Studio version mismatch, where certain versions incorrectly sync AMS assignments or expect an external spool.
  • Latest on both
• PTFE routing or tight filament path, which causes the feeder motor to fail during loading and produces feed or communication errors.
  • Issue happens with or without the PTFE tubes connected
• Slot-specific feeder or sensor problems inside the AMS Lite, where one spool position repeatedly fails during multi-colour prints.
  • Can’t get to this point, as this happens on power up, before prints can even be attempted

Sadly, none of what you suggested was an issue.

[Shadows]

That’s really odd, I’ll look a bit closer..

Uno momento

[Trident_Productions]

Any other ideas? Still sitting with flashing red LEDs

[Shadows]

I’m a bit stuck at the moment sorry, I’ll keep on thinking and hopefully we can resolve this soon..

Cheers,

[Neiljt]

Do you have the Ams in the correct port ? there are two , do you have the correct ams firmware installed ? ( not the ams pro firmware ?) there are two,

AMS lite can not be detected by the printer | Bambu Lab Wiki

A1 Series AMS Connection Guide | Bambu Lab Wiki

[Trident_Productions]

There are two ports, but it has worked before in either

[Bullocks]

Intermittent [works, then doesnt] I would suspect cables and connectors. But it looks like thats the rigor you’ve already done.

There’s some pretty extensive cable testing here, AMS lite can not be detected by the printer | Bambu Lab Wiki although I’m not sure if anyone but support can help interpret the results

[Trident_Productions]

I just picked up a multimeter today, and surprisingly enough, the resistances I measured were all spot on to what you’d expect to see from the unit if it was fully functional.

I’m truly at a loss.

[Bullocks]

Disconnect AMS, hang up an [external] spool, and see if it can process a print fine without the AMS?

You mentioned 2024, how many hours? Mine have started developing Issues© between 2500-5000, but like minor, spring retention failure or single motor failure, not fatal like this.

[Trident_Productions]

Honestly, I have no clue how many hours, is there an easy way to figure that out?

I’ve never had an issue in the past with an eternal spool, but I’ll see if that works.

[Neiljt]

Bambu Lab A1 | Multi-color 3D Printer | Bambu Lab UK Store

Watch the offical unpacking video from the store if you have lost the manual, 5 mins 30 sec

There is also a new updated wiki

A1 | Bambu Lab Wiki

[Trident_Productions]

Yep. I still have my manual, but I have already done all this. And the wiki confirms what I already knew; it does not matter which AMS port is used, as there are two of them.

Plug the AMS lite 4-pin connector into the port on the A1 mini. (either one)

Based on the response to my support ticket, the AMS Mainboard is likely at fault.

[Neiljt]

A1 mini FAQ | Bambu Lab Wiki

[Trident_Productions]

I do not have an A1 Mini.