Hi all.
Need to determine ( with little electronics knowledge or understanding ) if I can replace the IRLB8743 mosfet, used for the bed heater, with a IRFZ44N mosfet ?
reason : Printer runnning fine for 2 years. Marlin on Mega with Ramps.
Tonight at end of a 3 hr print I smell hot electrics.
6 layers to go so I let it finish.
Then the graphic LCD display shows 'Err: maxtemp bed' and I see the bed temp at 250C ( same as the max setting in the config file ).
I reset the Mega after the print completed and allowed it to cool.
First suspicion was a faulty wire to the bed thermistor. So powered-on and moved the bed ( Y axis on Prusa i3 style printer ).
There were no sudden changes to the thermistor reading as I would expect with a damaged wiring harness
Instead, the bed temp started climbing non-stop to over 70C before I turned off the power.
The mosfet on the Ramps board for the bed heater is very hot, so I suspect that it is faulty and is stuck in an 'always on' state.
I am unable to get a replacement IRLB8743 ( we are in Africa, and at the start of a long weekend ) but I do have a few of the IRFZ44N mosfets.
Can I use those instead ?
