HP L26500 banding randomly

[JoeBoomer]

Printer has been banding intermittently for the last day or two. After some trial & error and further analysis, it looks like I'm dropping nozzles as printing progresses. It initially seemed to be the Magenta (#5) ph, but it looks like I'm having problems with Y & K too (based on ph test print).


I replaced both Magenta & Light Magenta printheads earlier today, but ph test prints came out just as bad. I replaced Y & K printheads earlier this week.


Setup

L26500
10 Pass
3M IJ 180c-10 Control Tac
Printing solid color right now (1795C)

Environment Temps
70ºf @ 30% Humidity

Printer Temps

Drying: 129
Curing: 249
Vacuum: 29

Drying Temp Offset: 4
Warming Offset: 0
Heat Airflow: 40

===============

Update:

I just replaced ph cleaning kit and funnel. Test print looks roughly the same. The area with the dropped nozzles is the same location. It's actually happening on multiple ph's too.

I'll update as I go, but if anyone has any ideas fire away.

Thanks team!

 

[P Wagner]

Printer has been banding intermittently for the last day or two. After some trial & error and further analysis, it looks like I'm dropping nozzles as printing progresses. It initially seemed to be the Magenta (#5) ph, but it looks like I'm having problems with Y & K too (based on ph test print).


I replaced both Magenta & Light Magenta printheads earlier today, but ph test prints came out just as bad. I replaced Y & K printheads earlier this week.


Setup

L26500
10 Pass
3M IJ 180c-10 Control Tac
Printing solid color right now (1795C)

Environment Temps
70ºf @ 30% Humidity

Printer Temps

Drying: 129
Curing: 249
Vacuum: 29

Drying Temp Offset: 4
Warming Offset: 0
Heat Airflow: 40

===============

Update:

I just replaced ph cleaning kit and funnel. Test print looks roughly the same. The area with the dropped nozzles is the same location. It's actually happening on multiple ph's too.

I'll update as I go, but if anyone has any ideas fire away.

Thanks team!

It sounds like you are losing nozzles during the print run. Assuming that they return after a period of inactivity, here is what I would suggest doing (sequentially, in order):

1) Reduce the curing heat. You should not need anywhere near 249 degrees for that media. You could be losing nozzles from this being too hot.
2) Turn on the Gutter (left side). This is called color bars in some RIPs. This will exercise all colors on a band in each pass.
3) Enable the InterSwath Delay value in the printer (ink menu > Image Quality Maintenance > InterSwath Delay). The maximum value is 0.4 seconds for self adhesive.