DC 700 mottle 80gsm stock

[Nzer]

Hi all

Have a DC700 shows mottle in 80gsm stock. Can reproduce best at 50 % half tone internal test prints More noticeable when using two or more colours, especially bad with magenta cyan 50% mix. Never completely goes away but does improve and deteriorate, Can hard stop to confirm image on belt good, pre fused print on paper shows defect. All heavier weights seem ok.

Tried several different papers all freshly opened xerox branded. Have tried / tested to date - Adj transfer voltages in custom paper settings, Ibt belt assy, 2nd btr, 2nd btr hvps, IOT nvm reset, mcu pwb. All hfsis o.k. No errors in temp or humidity sensor nvms

Any suggestion greatly appreciated.

[Jake2o]

Low toner concentration or worn developer.

[Nzer]

Thanks for your response, I have a bit more info after spending time at the machine, The Toner and ATC read well but have replaced a set of dev tanks, along with MOB/ATC sensor.

They are printing a large run of booklets of 8 2-sided A3 pages with one colour image approx A5 size the rest is black text. Last two mornings the colour image is pretty reasonable for plain stock but starts to deteriorate after about 100 booklets, by about 140 the image is completely mottled out. then any half tone prints or procon pages show the defect, procon on and off both affected. Cant confirm but seems that after the machine is left at rest for a long period it improves e.g.. overnight. (two mornings in a row first thing it looks o.k)

Found a Fuji Japanese bulletin about low image on long runs causing probs in the dev tanks and bead carry over, changed NVM as said to allow the machine to print toner bands internally to clean the toner/dev to help resolve this issue but no luck, this also does not explain why if I swap the stock to 100 colortech it looks perfect when the defect is at its worse. (maybe the colortech being smoother doesn't show the problem?)

Still looks like a secondary transfer issue to me. Out of nothing to loose strategy have tested by swapping out Dev Bias and BCR HVPS's, 2nd BTR lead. Toned machine up considerably. Ran 60 halftones in all colours to clean devs, possibly looked a bit better for a few prints

Plan of attack for tomorrow is hopefully get a good image in the morning, record all values in max setup then run to fail and compare values and hopefully something stands out.

Static Build up?

Any ideas appreciated as I'm nearly all out

[adriansto]

As baseline procedure do a good machine cleaning and change or deep clean all machine filters.
Same procedure for the RIP server.
What software version is on to machine ?

[Nzer]

Machine On latest Fuji Xerox Firmware 1.130.9 Both CC filters are new Suction/Ozone near new. Machine is spotless inside,was recently refurbed by Xerox, this client has only had it 6 months and run less than 50k, Total Count 1.7 Million, customer very rarely runs 80 gsm on more than a few pages at a time, they checked on samples left from a run of this job when they first got the machine and shows the same defect -they didn't notice last time as they only looked at the first few prints.

[adriansto]

Send me mail at stoadis@gmail.com.
I have two technical bulletins about this and I will send you

[Nzer]

Thanks for the bulletins, Have tried the custom settings for the paper in increments from min to max, and bias contacts, Had a complete transfer belt assy so that covers off the back up roll, all heavyweight seem o.k although this cust does not usually do long runs, Have hard stopped and am confident that it is pre fuser but I do have the half latch values so will try to see if helps - paper is just plain office paper.

Thanks Again will revisit tomorrow

[Nzer]

Revisited with little success, but think it has to do with running a large job with low toner down causing grief with the dev tanks,

Stopped machine when showing the defect, vacuumed around the front of the dev tanks and ran 40 A3 full colour 60% halftones, restarted job and got to approx 100 sets before image started to go off again, will test this job on another 700 to see what happens,

[Scarecrow]

Revisited with little success, but think it has to do with running a large job with low toner down causing grief with the dev tanks,

Stopped machine when showing the defect, vacuumed around the front of the dev tanks and ran 40 A3 full colour 60% halftones, restarted job and got to approx 100 sets before image started to go off again, will test this job on another 700 to see what happens,

So Nzer, is the image still ok on the itb when the problem reappears? Ok after transfer? When you changed to the colortech, the mottle is not there. Does it reappear when the 80gsm is run imediately afterward? Has paper type/brand been eliminated? You mentioned the image is fine until entering the fuser. Seems like that would eliminate everything in the development process. Are you sure the problem is not static prefuser? Found a baffle in a docutech that was not grounded causing jamming. Some plastics are are designed to be conductive. Could there be a problem of static build up (or drain) prefuser if the image is ok after transfer?

[Nzer]

So Nzer, is the image still ok on the itb when the problem reappears? Ok after transfer? When you changed to the colortech, the mottle is not there. Does it reappear when the 80gsm is run imediately afterward? Has paper type/brand been eliminated? You mentioned the image is fine until entering the fuser. Seems like that would eliminate everything in the development process. Are you sure the problem is not static prefuser? Found a baffle in a docutech that was not grounded causing jamming. Some plastics are are designed to be conductive. Could there be a problem of static build up (or drain) prefuser if the image is ok after transfer?

From what I can tell image looks good on the belt, Can see fault on paper post 2nd BTR before fuser (defect starts at contact point with 2nd btr), yes if swapping back to the 80gsm defect still there, tried three Xerox branded stocks and 1 non xerox - all new unopened, Yes still thinking it could be static, To date the only way to alleviate has been to leave the machine alone as three mornings in a row image is perfect, and once defect appears only thing so far that helped was by running heavy coverage half tone runs (in the 80 stock), not sure if this would help with static but must be stabilizing something, may try to get a probe on the 2nd btr to measure any change during the run and check for earthing on the the ppr path.

Thanks