I have my heatbead connected to P1.23.
So when I heat up the heatbed it goes sloooow and never reaches max temp. (usually just stops at temps just below 55 celsius)
So out the multimeter: heatbed resistance about 1.1Ohm. That should be fine?!?
But:
Voltage output at the regulator (1.23) only reads 11.17V !!!
Shouldn’t that be the same as the other two big mosfets (just above 12V)
Has anyone an idea what I do wrong?
Imported from wikidot
1.1ohm at 12v that should be about 10.9A, which is perfectly fine for Smoothie.
You shouldn’t worry about voltage being 1 volt lower than the power supply, that’s just normal.
*However*, P1.23 is the third big mosfet. That mosfet’s power input is shared with the stepper motors. This means that you are most certainly going over the maximum rated current of that input ( 12.5A ). For a heated bed you MUST be using the first or second big mosfet, and it’s power input. And you must always be sure to not go over the maximum current for any input, or output. Did you read the documentation regarding this ? It’s pretty complete …
Thanks, got it.
Which could explain some irratical behaviour when printing.
Wanted to power the heatbed independently anyway. Now that I use 1.23 just as signal pin for my HB and all is fine.
Again. Thank you