Single AMS 2 Pro + External PSU = Abnormal current

Bambu Lab H2 Series
1

Hi all,

I have a single AMS 2 Pro connected to my printer, currently running the latest beta firmware.

When printing, if I start the drying process (which is possible using the beta firmware), I receive a warning stating that I should connect a power adapter for better drying performance, since there isn’t enough current available through the 6-pin connector. Once I connect the external power supply, the warning disappears.

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However, if I leave the external power supply connected and try to start the drying function while the printer is idle (not printing), I get an “abnormal current on sensor heater 1” error. If I disconnect the external power supply, the error no longer occurs.

At the moment, the only way I can run drying with the external power supply connected is while actively printing. Once printing stops, I have to unplug the power supply to avoid the error.

I purchased the external power supply after installing the beta firmware, so I never tested this setup on a stable firmware version and have never experienced this issue before. Has anyone else with a single AMS 2 Pro and an external power supply experienced this behavior? I’m trying to determine whether this is expected behavior, a beta firmware issue, or a hardware problem.

Thanks,

FT

2

That’s almost certainly going to be a code bug. If so, they’ll fix it.

It’s “Beta” FW for a reason. Might not work exactly as advertised. :slight_smile:

3

I hope so. I just posted to check whether anyone with a single AMS 2 Pro and an external power supply has experienced the same issue. I’m also not 100% sure it’s not related to the power supply itself. It’s not the original one from Bambu, but it has the same specifications (24V and 4A).

4

Your problem description is a classic kind of software mistake. New feature is is added to the software and tested and it works as intended. But it keeps something else that used to work from working correctly. The old feature works if used as originally designed, but not when confronted by a system state that’s established by the new feature.

5

I did experience something similar on released firmware, but it was because Im an idiot and didn’t plug the power cord into the power strip behind the stand, I just routed the cord there.

I think RocketSled is onto the issue, a logic kind of thing that was overlooked.