bizhub 423 Focus

[blackcat4866]

The call started out pretty mundane: C0208, with paper loaded at the left side of tray #4.

bizhub 423 scanner focus.jpg

After clearing the error I was testing out the other trays, and I noticed that 50mm of the trailing edge of the legal paper was coming out black & blurry. Obviously it's a scanner focus problem, but the thing about focus issues is that it's so easy to make it much worse, before you make it better. I was happy to have an issue to wrap my head around. These samples are on ledger paper.

The mirrors were all set snugly in their mounts, and mostly parallel based on some rough measurements. The machine was not obviously mistreated, nor had excessive wear. The cables were tight, cable drums are secure on the shaft, cables not overwrapped, rails clean and lubricated, glides intact.

I came around to the CCD. While experimenting with the image width, I snugged only the two screws at the left of the CCD. Suddenly the black/blurry area was larger. Aha!! The loose screws at the right let the lens/CCD tip down .. so I need it to tip up. Ordinarily I wouldn't touch the painted adjuster screws. I suppose I could have shimmed it with mylar, but that's what those screws are for. Why nor use them?

With the CCD back at it's starting position, it took nearly 1 1/4 turns to the left screw, and 1/2 turn to the rear screw to bring back a good focus. I'm just wondering how it could get this far out of focus without clear physical damage. The paint marks were unbroken. =^..^=