AR-M350U CQ problem

[nathansipe]

The machine is making a shading across the bottom 3 inches of the page. The shading runs from lead edge to trail edge on the front side. The only problem is on the bottom of the page and gets more severe as more copies are made.

Customer had a line across the bottom of the page, so a coworker replaced the drum unit and transfer unit with rebuilt units Friday while I was on leave. It made good copies and he left. They called yesterday saying now it is shading where the line was. I cleaned the laser slit glass, and any other toner from machine. I thought it would be main charge, so I changed main chargers again but nothing changed. It is not an optical problem via the test prints. I also copied a blank piece of paper and it still does it. Image is on the drum. I dont think its laser related or it would be shaded in the other direction since the laser writes across the drum.

Ideas?

[Lawrence]

I would look at your DV and DV unit. How many copies are on the machine and how many copies on this batch of DV? We always change Drum and DV together especially on this model. After 100k on the DV they dust like crazy.

DV units for this model are dirt cheap. Just make sure you check the doctor blade gap. Ive had a few right out of the box with incorrect gaps.

I had a ARM350 that was a lemon from the start and it used to do that. All we could do was change the DV and hope it lasted longer the next time.

[johnbla]

Agree with Lawrence

Dv Mag roller needs to be cleaned until shiney...

[Jaws]

The left door is not closed all the way.
The back latch is probably hooked but not the front.
Went round and round on a few until I figured it out.

[mtech]

Check this out. You changed the drum, did you change the blade? As was said, do the developer and drum and blade at the same time. There is a very weird thing that I have seen many times with this model. After a full PM (DV, drum, blade, main charge) you get dark shading! Almost all grey background! The copies look worse than before you did the PM. CHECK THE TONER CARTRIDGE! if it is below 25% change it and run a hundred copies and you will be amazed! Sharp refused to acknowledge this but I swear it is real! I have ran into this a bunch of times. Nothing worse than doing a complete pm and seeing gray background all over. This got me good the first time! Spent hours trying to figure it out! A friend I talked to said he had a similar issue and thought that after a toner change it went away. I tried it out of desperation and holy crap it worked! I do not know why and Sharp was no help. Good luck ( change that blade and clean behind the drum first as you did not mention you did that) good luck!

[blackcat4866]

Unless the specs are way out of wack I have to disagree Jaws. Its usually a light area (poor transfer at the machine rear), because the customer only closes at the left front corner. Usually accompanied by significant skew.

To get dark copies the gamma or exposures would have to be cranked to overcompensate.

How do internal test prints look (sim 64-1, personally I get the most information from pattern 64 or 83)? =^..^=

[mtech]

Some of the P series machines I worked on had issues where the mag roller would turn black with a coating of toner, but Sharp changed the toner a bunch of times to fix this.

[tmaged]

If the mag roller is dark at all, replace the DV unit & DV. Only use OEM toner on these & you should be good.

BTW, you can usually change the main charge voltage to get by for a little but. Change 8-2. The default is usually like 651, change the main charge AE to 800 & the printer main charge if they're printing to it. Don't forget to change it back after replacing the DV unit & DV.

[nathansipe]

Thanks for the help guys. I will use this info for future machines, because the customer opted to just buy a new machine from us. Thats always a sure fix.