Build plate now lifts off FEP on Initial Layer??

[Keithy2021]

Hi everyone, newbie here!!

I've a Mars 2 Mono, approx 2 months old, printed about 6 prints, all great. I upgraded the firmware when I received the machine & its worked great until now.

Suddenly for some reason when starting a print the build plate lifts off the FEP by 21mm after setting Z to Zero (which has worked fine on all the prints with a piece of A4 paper) so the initial layer now prints on the FEP as the build plate isn't there to form on?

I've tried re-running the good prints but the printer is doing the same action on all the prints? I've done dry runs so I can see & measure the build plate lift, there's nothing I can find online & the forums to explain this, is there a fault now with the printer, maybe the Z sensor?? There's no adjustment on the printer. I've tried reloading the firmware but it says it's on the current one.

Stumped !!!!! 

Anybody else had this issue??

Thanks for any help !!

[cliffyk]

Here's a post I made a while back re: the alignment procedure and the difference between the mechanical process and using the "Z=0" firmware function--if the platen is properly aligned mechanically the "Z=0" function is not needed.

There are two "zero" positions for the platen. One is electro-mechanical, determined byte Z-axis limit switch--the other a "logical" zero position set in NVRAM by pressing the "Z=0" button. In operation the platen will always initially fall to the limit switch position first to determine the "real" end of travel, it will then rise to the logical "Zero" as set with the "Z=0" button. The logical zero position can only be attained via gCode positioning commands. Pressing "Home" will always send the platen to the limit switch controlled end-of-stroke.

It may be that he value stored in NVRAM has been scrambled, causing what you are observing.

Try resetting the logical zero point by pressing the "Z=0" button with the platen in the Home position (do not raise it manually).