"LSU Error" message display in LCD device. SCX 4834FN

1. LSU defect - LSU LD dead due to manufacturing line over-leakage voltage

2. Mainboard Q11 devise defect - it can not output 5V voltage for controlling the LSU

Change the mainboard - if working do a firmware update you will get this on the samsung wepsite.

IF not put the old board back and replace the lsu. most of the times it is the lsu. you can also open the lsu and see if the moter is turning free. oil it a bit and sume times this sorts the problem out.