The Velleman 15 power supply is rated at 100 watts, or about 6.6 amps. Mine overheats and shuts down (briefly) during long prints.
I measured the resistance of the heater bed to be about 5.5 ohms. So, the heater bed alone draws about 2.7 amps when switched on.
The nominal heater bed résistance is about 7 ohms, and draws about 2.1 amps.
The difference of 0.6 amps (0.9 watts) seems small, but could this be why my power supply overheats and shuts down? Could the problem be the heat bed instead of the power supply?
If I replace the power supply with a 15 volt 150 watt power supply (10 amps), does the output require a ferrite core high frequency filter? I would assume not because it is a switching regulator supply that has a ferrite core instead of an iron transformer. So it is more efficient and runs cooler than a conventional supply. Also, it is a goodr filter for high frequencies on the AC side.
The supplied power supply is a SMPSU, just like the one you’ve replaced it with. The ferrite is necessary, to filter out any noise that might be superimposed onto the DC output. This noise can interact with the electronics on the main board.
It is strange that the supplied power supply resets. Is the room temperature >30°C? If you wish, you can return it for inspection/exchange.
Please call (817) 284 77 85 for RMA#
In order to run a job with the original power supply I turn off the heated bed to reduce the load. That requires using tape on the bed for adhesion. When the supply shuts down it is very hot to the touch. It only shuts down briefly, then immediately resets - but of course the job is interrupted and the print ruined. My guess is that the supply has a protection feature that stops it from overheating to the point where it will damage itself. The thing that tipped me off that the supply was failing was that the LED light ring above the extruder blinked, but the room lights did not blink. The second time it happened I saw the blue light on the supply blink.
I plan to return the supply to Dallas when they answer my email. If I don’t hear from them after the weekend, then I’ll call during business hours. I can’t be the only one who has had power supply problems. Adding a second 24 volt supply for the heated bed would solve the problem, and allow much faster heating of the bed. But it requires using the 15V bed output to switch the 24 volt supply.
I noticed that 12V fan is also run on 15 volts, at least when it is running at 100%.