HMS 0300-0100-0001-000C: heatbed working at full load for too long
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HMS 0300-0100-0001-000C means the heatbed has been running at full power for longer than the firmware expects, and it warns that the temperature control system may be abnormal. Read the word “may” carefully. A bed working flat out is often a bed fighting a cold room, and that is a situation you can fix without replacing anything.
Affected machines: A1 series. These are open-frame printers with no enclosure, so the bed loses heat directly to the room. The warmer the target and the colder the room, the longer the heater stays at full power, and there is a point where the firmware decides that is no longer normal.
Where to buy
The room comes first
Measure the room. A bed asked for 100 degC in a workshop at 12 degC is doing far more work than the same bed in a room at 22 degC, and on an open frame there is nothing between the two. Below about 18 degC, expect higher bed targets to be slow and this warning to appear.
Then look for a draught. A window, an outside door, an air conditioning vent or a desk fan pointed at the machine all strip heat off a bed faster than still air, and a draught is worse than a generally cold room because it is concentrated.
Only after those two is the machine a suspect. Measure the bed sensor cold: around 100k ohm. A sensor reading high makes the controller believe the bed is colder than it is, so it keeps the heater at full power and produces exactly this warning from a healthy heater.
Printer warns that the heatbed has worked at full load for a long time
Cold room or a draught, a sensor reading high, or a plate that is not sitting flat
- Measure the room temperature. Below about 18 degC, expect this on high bed targets.
- Move the printer away from windows, outside walls, doorways and air conditioning vents.
- Check that nothing is blowing across the bed, including your own cooling fans on other machines.
- Confirm the build plate sits flat and fully seated, since a raised corner leaves an air gap that slows heating.
- Measure the bed sensor cold. Around 100k ohm is healthy; a high reading makes the controller overdrive the heater.
- If the room is warm, the plate is flat and the sensor is healthy, record the code and raise a ticket.
Consider whether you need the temperature you asked for. Many PLA profiles use 60 degC out of habit when 55 works just as well, and on a cold day that difference is the whole problem.
The related fault is heatbed heats too slowly. Our pages on bed temperature and enclosures explain how much the room affects an open printer, and the troubleshooting index covers the rest.
HMS 0300-0100-0001-000C FAQ
Is my bed failing?
Usually not. This is a warning that it is working hard, and a cold room explains most of them.
Can I keep printing?
Yes, while you watch it. If the bed also fails to reach temperature, treat that as the more serious symptom.
Would an enclosure help?
On an open-frame machine it would, though these printers are not designed for one. Fixing the draught is the simpler move.
Does the plate matter?
Yes. A sheet that does not sit flat leaves an air gap, and air is a very good insulator.
LayerWalker
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