One color pair doesn't prime up after the print head replacement

Open Discussion
1

Hi everyone! I’d like to see if anyone had any experience of one color pair being stubborn and not priming after print head replacement. The machine is Stylus Pro 9890. The stubborn pair is LC/VLM. After the head replacement, I have run several cycles of Power Clean and individual color pairs clean. When that didn’t help I performed an initial fill that brought up all color pairs except this one and till now there is a blank nozzle test for these two colors.
Any advice to troubleshoot it further would be highly appreciated.

Thanks!

2

Dear Alex,

this indicates a blocked/locked damper. Did you replace the ink selector unit with the head replacement. That is required.

regards
-Walker

3

Hi Walker,

No, the ink selector wasn’t replaced. The print head had a partial nozzle failure on the yellow channel and the rest was functioning properly. I have replaced the print head only and now see LC/VLM pair not priming at all while the rest of the channels function as they should. I suspect the cap seal or ink evacuation tube from that channel may be blocked or the damper is blocked. Visually there is some ink in the damper for this channel but it is not being drawn into the head. Is there a way to create suction in the CAP station for just one problem channel manually with head parked to create the necessary draw? Or maybe a way to assure there are no plugged lines coming from this channel into the pump?

Thanks

Alex

4

The problem was solved with manual priming of the damper with a syringe. First I made sure the cartridges were pressurized to avoid creating a vacuum in the dampers.
Then I have inserted a fitting connected to a syringe via a flexible capillary tube and drew about one cubic centimeter of ink. Then I have disconnected from the damper and drew a bit of air into the syringe to have a cushion above the fluid level.
After that, I have primed the tube with the ink by pushing on the plunger and then connected the tube to the print head connector for the same color and injected some of the ink. The air cushion was helping to avoid applying excessive hydraulic pressure to the print head. Having a soft towel under the head helps to avoid the mess as ink leaves come out from the nozzles.
After that, I have re-attached the ink selector to the print head and ran the power clean cycle. All channels came back and were firing at 100%.