I use a Balco i3 with 5.1 board and the 4.0.6 firmware. with BLTouch 3v1
It worked very well for a time. I like the FWare.
I decided to adjust again my Bed PID since I use another glass plate on top . Has then worked fine too. But now after maybe 20 minutes printing on a 100°C Bed T°, the indicated T° on screen slowly goes down to 96 and initiates then a stop because of a too big difference between set and resulting T°. It is proved that the T° runaway detection works.
New external 25A Mosfet : no difference
New original bed and thermistor : no difference
The PWM signal on normal behavior at the beginning varies from 45 to 100% full load and keeps the T° stable at 100+0-1°C which is perfect . If I had used a scope from the beginning , I would not have bought a new bed and ….
When the indicated T° drops , I can see the PWM ( and by thus also the MosFET current monitored on a Scope meter ) going to 100% load. Of course , the real bed T° goes to Max…. At indicated 96°C : failure.
The thing I have difficulties to understand is the fact that preheating the bed to 100°C works perfectly for hours and the PWM is perfectly working fine… until I decide to print.
I tried Cura 4.6, & Prusa Slicer 2.2.0 with and without PID settings in the GCode…
What do I miss somewhere….?
Thanks in advance