To reset the H4 condition on your Sharp AL1642 series copier press the following key's in sequence and as quickly
as possible (with 4 seconds for the first 4 keys)
Press "C" then the far left key (exposure mode) then the "C" key then the far left again.
So in other words C, far left, C, far left
Some model's use 2 other initial codes, so you may need to use one of these 2 alternate codes to get your display to go blank. The rest of the procedure is the same.
Alternate codes are: #, * , C, * or pound,star,C,star and also
#, Interupt, C, Interupt
If done correctly the display should go blank.
Now key in 14 as if you were going to make 14 copies.
Now press the print button.
The machine should reset and the code should be gone.
9 times out of 10 this is a false code that pops up due to power
surges or noise.
If the code comes back this means you have a heater lamp or thermal fuse (more common) failure in the fusing area and will need service.
Good Luck and Thank You for using Fixya.