Bed heater does not stay on

General Discussion
1

I have a strange problem with my setup.

I have a tronxy x5sa 500 pro. I have put a skr 1.4 turbo board in it, running Octoprint and klipper. I have replaced the bed leveling sensor with a bltouch. The bed heater if running with a mosfet.

My issue is that when I run a PID tune on the bed heater, everything seems to work fine. However, when I go to print or set the bed temp to heat up (60 c) the heater will not stay on. It comes on for maybe .5 sec then shuts off for .5 sec. The bed does not heat properly and I get an error that the heater was not heating as expected.

Any sugestions?

2

Please post your klippy.log

3

here is the log.

klippy.log (1.3 MB)

4

Some comments:

bed_mesh:

  • 2500 probe points seems extremely high.
  • At best it will not give any operational benefit (it is a 3D printer and not an electron microprobe)
  • Worst case it will create unwanted effects
  • bed_mesh should be created at heated and stabilized bed
  • Different bed temperatures for different filament should be meshed individually

→ For testing purposes and failure isolation, I’d take out the mesh at least temporarily

[heater_bed]:

  • Check the usual suspects like hardware defects (MOSFET, thermistor, SSR etc)

→ For testing purposes switch to watermark and see if the situation improves:

[heater_bed]
heater_pin = P2.5
sensor_type = EPCOS 100K B57560G104F
sensor_pin = P0.25
min_temp = 0
max_temp = 130
control: watermark
max_delta: 2.0

As the bed is slow to react to temperature changes, the benefit of PID is low anyway IMO.

Do the fault isolation step by step, i.e. only change one parameter at a time.

5

OK.

Changed to a 10x10 bed mesh, no difference.
changed to watermark control, works as expected. heater stays on.
changed back to pid, problem returns. on for .5 sec, off for .5 sec
will leave it on watermark for now, to get it working.
However what confuses me is that the pid calibration works, the heater acts normally during calibration, then does not under regular operation.

6

I’m running a SKR 1.4T in one of my printers as well and I can confirm PID generally works with this board. Could be many things, like unstable power supply, faulty MOSFET etc.

If you do not go to a very high load / temperature you could probably try HE1 to drive your bed. Just make sure the MOSFET does not start glowing red.