Another Bambu Lab A1 Malfunction

In October 2024, I wrote about my Bambu Lab A1 3D printer heatbed temperature malfunction. Because the malfunction occurred within the 30-day replacement window, I was able to return the printer and have a replacement printer sent to me.

I have had a great experience with my replacement Bambu Lab A1 3D printer until November 2025 when I started witnessing that the printer would randomly lose all power. Sometimes it would happen during the pre-print routines (e.g., bed leveling, bed heating, filament purging), and sometimes it would happen in the middle of a print. Despite the main power switch remaining in the ON position, the printer would lose power, the fans would turn off, the screen would go blank and unresponsive, and the Bambu Studio slicer would lose communication with the printer. Initially this occurred infrequently, but it seemed to occur progressively more frequently over time to the point where most of my prints would fail due to unexpected power loss.

Because of the prior heatbed temperature malfunction in October 2024 and the current power loss malfunction in November 2025, I have started to question the durability of Bambu Lab 3D printers. Nevertheless, I bought another Bambu Lab A1 for three primary reasons. First, I enjoy participating in the Bambub Lab ecosystem where things just work (that is, until my printer breaks down). Second, I have meticulously set up air purifiers both inside and adjacent to my Bambu Lab A1 third party enclosure and didn’t want to re-configure my setup with a different printer’s form factor. I had considered upgrading to the Bambu Lab P2S, but that will have to wait. Third, Bambu Lab was in the midst of their Black Friday sale, and the A1 printer was on sale for $279 (normally $399).

Meanwhile, I asked ChatGPT to help me diagnose the problem, in hopes that maybe I could acquire parts to fix the older printer. After describing my scenario, ChatGPT concluded that there was an 80%+ likelihood that the power supply unit was responsible for the power loss. The other possibilities were a loose power connector (15%), a mainboard power regulator failure (5%), or a firmware or software issue (<1%). It encouraged me to contact Bambu Lab Support and stated that even though my printer was just past the 1-year warranty period, they might still help me out. I had previously written about the Bambu Lab Warranty, and at the time I had focused on the language related to returns, refunds, and replacement within a 30-day window. Looking more closely at the general warranty language dated November 18, 2025, it also says that there is a “2-year warranty for for consumers from the EU, Switzerland, Norway and Iceland” and a “1-year warranty for the rest of the world (any country not mentioned above).”

I submitted a support ticket to Bambu Lab, and they directed me to the Bambu Lab Wiki for “Printer Circuit Failure Troubleshooting - A1”. I confirmed that all indicator lights were in their normal status.

• The TH Board indicator light was constantly green
• The MC Board green light blinked every 5 seconds
• The AP Board had one green light blinking once per second
• The HMS indicator light was constantly on

Based on questions from Bambu Lab Support, I also confirmed that the fuse was NOT blown, and the power switch had good contacts and no corrosion. Also, I measured the AC power input at terminals #4 (neutral wire) and #5 (live wire) of the power module, and the multimeter reading was 123.8 volts—a normal value in the United States.

Bambu Lab Support asked me if the main power indicator light would turn off when the machine is powered off, and I confirmed that it did. They also asked me to confirm that the 24V power module indicator light was a steady green light (normal state) when the machine is powered on, and I confirmed that it was steady green. They also asked me to verify that connections for terminals #1 through #5 on the power supply were properly inserted, and as far as I could tell, they were. Based on this information, they decided to send me a power switch assembly and noted that despite my printer exceeding the 1-year warranty period, “This component is a special free replacement.”

To me, this gesture from Bambu Lab went a long way toward mitigating my frustration with my 2nd A1 printer malfunction in 13 months. Also, ChatGPT was correct in encouraging me to contact Bambu Lab Support based on a history of them supporting printers past the warranty period. Although I still question the durability of Bambu Lab printers, I must admit that I have received very good support that has exceeded my expectations.

However, one main question remains. Although ChatGPT seemed at least 80% confident that the power supply unit was to blame, Bambu Lab Support sent me a free replacement part for a power switch assembly which ChatGPT suggested was a much less likely culprit. I updated ChatGPT with my recent interactions with Bambu Lab Support and asked if they perhaps wanted to first have me replace the power switch assembly because it was a less expensive part, and ChatGPT agreed with my assessment. It went on to say that it still felt that the power supply was still the most likely culprit and suggested that I replace the power switch assembly as instructed by Bambu Lab Support and see if that fixes my problem. If I still experience power loss after replacing the power switch assembly, then that makes the power supply unit the only remaining rational explanation. ChatGPT communicated to me that this is probably just the normal troubleshooting algorithm they go through. Bambu Lab Support has not commented on their protocol, but the ChatGPT response seems to make logical sense.

So now I anxiously await receipt of my free replacement power switch assembly. I hope it fixes the power loss issue but realistically expect that I may have to reopen the support ticket and ask for further assistance, with possible replacement of the power supply as a result. Stay tuned for what happens next!