Helge

I received a replacement for the power supply today. It's a GST220A24-R7B and so I set the power budget back to: Total: 200W Buildplate: 160W Extruder: 35W The UM2 now prints again like a charm. Did a few test prints with excellent results. The previously clearly visible flickering of the LEDs is reduced beyond recognition. It seems, as if strong visible flickering of the LEDs may be taken as a sign for a dying power supply.

Since all functions (nozzle heating, bed heating, bed movement, print-head movement) are working fine when executed alone, I think that there is no short-circuit in the wiring within the printer. I checked the heating coils of both bed and nozzle and they show reasonable resistance values. Could be a degraded or broken capacitor in the power supply but there are metal shields glued on in a way that makes accessing components in the power supply nearly impossible. I ordered a replacement already and will have a look at the broken one later on. LED flickering got worse recently so I suspect degraded components as a cause for the issue. I will keep you informed.

With a total of 150W I am able to heat up the bed. It looked quite promising and I started the first print. When all axis are active and heating is on, the power fails again (when homing, raising the build plate and heating). At a total of 115W a bit of movement is possible but the power blacks out after the head is in front position. I even lowered to a total of 100W, but it seems that peaks during stepper movement are now even too much for the power supply. I see the LEDs flickering so I think that this is a sign of power instability. Switching them off didn't help either. All together, I'm stuck with only one of the functions possible at a time. I'll get a new power supply and will report if it worked. I'm quite positive, that it's the power supply.

Great, seems to be solved! After updating the firmware and setting the power budget, the printer is able to heat up the build plate again. LEDs flicker (they did this already, starting a while ago when printing), so I think it's the power supply that is broken in some way. Heating slows down, but at least I am able to print until I get a new power supply.

Thanks for the quick response. Since I got my UM2 when it was quite new, I got the older power supply (GS220A24-R7B). My printer did about 3400 hours of perfect printing before the issue. The failure is permanent, so it doesn't just switch off for a fraction of a second but stays off until I unplug it and reconnect to mains. It happened first time when printing at very high temperatures (which I usually don't do) so I suspect this to be the initial cause for the failure. Right now, I can't get to a state where resistance increases because of higher temperature. I turn the wheel just one degree above ambient and the power fails. I will install the software you mentioned and see if this will fix the issue.

I tried to print in Co-Polyester which requires high temperatures (nozzle 250-280°C, bed 100°C) on my UM2+. After several tries, always resulting in warping, the printer stopped dead with a power failure while printing. Ever since, the printer has a power failure, whenever I heat up the print bed. I checked the wiring and the resistance of the bed heating. The measured resistance of 3.3 Ohm seems reasonable for a heating element with about 165W at 24V. The power supply provides 24V when switched on a while after the last failure. Power stays on until I try to raise the bed temperature above ambient temperature. When experiencing a power failure, the output of the power supply drops close to zero. It seems as if the power supply suffers from an overload condition. I just wonder if this is caused by a broken bed heating or if the power supply simply broke after that long print.