Quote Originally Posted by sbillis View Post
Can you be more specific? Where is the point exactly you mention? any photos?
See the attached image....parts manual showing some parts of the ADU section entrance guide. The red circled screws are the ones to remove. The Green circled areas are where I mentioned I place my screw driver in between and then gently pinch the upper and lower guides just a little bit. When the screws are replaced back in, the gap between the upper and lower guides should be a little closer. The front side usually can be left alone, it is usually the back side that needs to be "tweaked". The blue circled items refer to the shaft and tabs I mentioned that have the 1 mm gap above and below the shaft as clearance. As I said, be gentle and sparing on how much you pinch the plates together. Too much pinch and you could introduce unwanted drag, which can also skew paper.

ADU sample..jpg
Also I would like to ask something more:
- Centering sensos (PF and ADU) must be on or off?
- 3mm gap from PF does it matters?
- FD,CD,Centering,Restart Timin must be done with A3 paper(11x17) or 13x19 or anything else customers using and what wheight.
- Skew can be corrected from ADU mechanical adjustment or from CD Skew software adj?
and maybe must importand
- Side 2 Lens adjustment must be ON for heavy stock? 300gsm with manual duplexing, does it matter?
or is effective only for auto-duplexing?

thanks and sorry for long questions
Turning off the censors is strictly optional. You can replace these if they are defective. There are service bulletins which have mentioned this in the past. Turning those off will eliminate the random shift, but at a cost. Image centering is automatic when they are on, but turn them off and the operator has to manually adjust front and backside registration. As mentioned elsewhere, you can adjust all the trays to center them all with each other as well as in duplex, but it is time consuming and not 100 percent. Especially since the LU202 or PF units do not have any mechanical adjustment for side registration. You have to electronically center the trays with duplex, and then you can mechanically adjust trays 1-3 to match the LU or PF unit, followed by tweaking here and there to center all the trays with each other. After that, the user has to tweak on a per job basis if they require duplex registration to be centered. It is a bear to do. Some techs would rather just replace the sensors, but from personal experience, I have found that doesn't always solve the issue. Glossy paper seems to be an issue with these sensors.

The 3mm gap does matter. In all cases, I have found this made the most difference when dealing with skews from the PF unit.

In all adjustments, I have used 24 lb 11x17. Generally, most shops would prefer you use the cheap stuff rather than the more expensive stocks. Keep that in mind when doing test prints when servicing. With the exception of course when dealing specifically with quality issues on certain stocks. I try my best to avoid using the expensive stuff where possible.

Some skewing can be corrected through the CD Skew adjust. Generally, if you eliminate the feed skew, you will likely eliminate any skew through the ADU, including duplex. The exception would be uneven pressure on any of the rollers as the paper passes through the unit. I've been fortunate. Of the dozen or so machines in my city, I haven't had any ADUs that had been 'warped' or bent, aside from the entrance guide I spoke of above. The specs call for a tolerance of 2 mm on 11x17 duplex where skew is concerned. All my machines have less than half a mm duplex. Auto skew adjust is off in all instances.

Side two lens adjustment is strictly a duplex function. The machine will not allow you to duplex weights above 257 gsm, you will have to manually refeed that stock, even if it is 100lb glossy text, which could easily pass through without issue. Some customers have "cheated" using this type paper. It works, but they run the risk of the fuser throwing an abnormal low temp code. Usually I just follow the service manual regarding which adjustments to make as I make them. There are prerequisite adjustments for various other adjustments, those should be performed for best results.

In the end, I have had the best results by trying to get the machine mechanically squared, and then after doing what I could there, going in and doing the electronic adjustments as needed.

Centering is about the only issues we sometimes have, but generally, the customers are quite content to use image adjust within the driver or CWS to compensate for side 1 to side two registration variances.