banding across

[tompika]

We have banding issue across(ws4500). It is in every seperate, in the same place, usually at light halftones, around 10%.
The blanket is new, the PIP is new, the doctor blade in the cleaning station is also new.
The stripes are in the same position in every separation, so it cannot be BID issue.
We have checked the PTE light it is working, we have checked the Exit fan, Exit suc. , Feed Fan, all work.
We have then checked the cleaning station flow rate, it is around 550 ml.
We have checked the cleaning station rollers, sponge(not new, it has 500k impressions) and wetting, they are fine.
What else to check? Is it writing head problem?

 

[mantman]

PIP and impression drum gears clean and lubricated?

 

[tompika]

yes, they are clean and lubricated, since the banding is parallel to the long side of the print (paper running direction) it is not a mechanical issue I think.

 

[mantman]

Well if not then exchange BID or try a new one. Had a similar problem close to yours and it was BID

 

[tompika]

We have changed the grids in the scorotrons and cleaned the inside of them with IPA and problem has gone! thanks for all the comments! have a nice day!

 

[mantman]

Bleh missed the parallel to long side. A better photo would helped faster

 

[Artos]

Check that the scorotron motor is working. It broke once for me and the print became streaky at intervals when the corona wire got dirty.