Pro6500

[WaveyDavey]

We have a 6500 in a print for pay enviroment,
the machine gives very poor coverage on light yellow or anything that has a light yellow content. the problem looks like bands and I would associate it with dirty coronas or scorotron grid.
all these items are changed and the problem is still there. KM are saying that the all 6500's will do this at anything below 30% tint on yellow!
is this correct? do others have the same issue or have you been able to resolve it?
customer is miffed as they say it was fine when new but I am not sure.

anyone have any comments would be great

Thanks

[Si@danwood]

Hi there, the most likely cause is the write unit.I had this problem only the other day.I suggest you take test prints of all four colours using pattern 53 set to 40 to determine which colours have this issue(normally is yellow) then swop over the write units with another colour (NOT BLACK) remebering to run i/o 46-00 to set up the write unit alignment.On my machine the yellow then came good so i have ordered a replacement unit.Also check to see which revision of write units are installed ! The identifing mark is a little sticker on the unit itself ,the latest which is RED.Prior units were marked purple,blue,green, none .The lastest prior to Red being purple (hope this makes sense)....Good Luck Si

[Haroldbfix]

We have a 6500 in a print for pay enviroment,
the machine gives very poor coverage on light yellow or anything that has a light yellow content. the problem looks like bands and I would associate it with dirty coronas or scorotron grid.
all these items are changed and the problem is still there. KM are saying that the all 6500's will do this at anything below 30% tint on yellow!
is this correct? do others have the same issue or have you been able to resolve it?
customer is miffed as they say it was fine when new but I am not sure.

anyone have any comments would be great

Thanks

If the banding are from front rear and only happens when running half tones. Try this attachment it will save you life.

[WaveyDavey]

thanks for the replies guys.
We had already fitted the new version write units which did improve things quite a bit but the underllying problem still exists.
thanks for that doc Harold interesting reading, where did it originate?

[random]

Perform the following adjustments in this order.

• Auto Drum Potential.
• Auto Gamma Adjustment Screen (select “0” and execute adjustment.) See SM pg. 281
• All Printer gamma Offset adjustment* See SM pg. 258,259.
• Gamma Sensor Adjustment. See SM pg. 262, 263.
• Calibrate Print Controller.

1. drum potential is done at auto-gamma so you can skip this adjustment.

If you don't calibrate the controller you should run another auto-gamma after which you should check your offsets again.

[Haroldbfix]

thanks for the replies guys.
We had already fitted the new version write units which did improve things quite a bit but the underllying problem still exists.
thanks for that doc Harold interesting reading, where did it originate?

We fought this issue on several machines. "Random" was very helpful with pointing us in the right direction. The rest of the info came from various posting, a bulletin, and personal research. You might say it was a team effort.