Need Help Mimaki JV150-130 - Right half of Magenta disappears after sitting idle. Prints perfectly while running. Head, cap, pump and dampers already replaced.

[cobo_design]

Hi everyone,


I'm hoping someone (especially Solventinkjet or Smoke_Jaguar) can help me troubleshoot a very strange issue on my Mimaki JV150-130 (DX7).


I've been chasing this problem for several days and I'm running out of ideas.

Symptoms​

• Only the right half of the Magenta nozzle bank drops out.
• The missing nozzles are always in the same area.
• The printer can print perfectly for an entire day with no banding or missing nozzles.
• The problem usually appears after the printer has been sitting idle or after the automatic power-off (30 minutes).
• Sometimes a Normal Fill Up Ink brings the magenta back to 100%, but other times it doesn't recover at all.
• During a Normal Cleaning, I can actually see the magenta firing normally at first, but after a second or two the right half changes from a normal stream into a very fine mist/spray.

Things already replaced or checked​

• New DX7 printhead (approximately 1 year old).
• New cap top (aftermarket).
• New pump.
• New dampers.
• Flat cables disconnected, cleaned and reinstalled.
• Cap position adjusted.
• Cap height adjusted.
• Air Pull Position adjusted.
• Several Normal, Hard and Ultra cleanings.
• Fill Up Ink.
• Overnight nozzle soak with cleaning solution.

Additional observations​

• If I push cleaning solution through the magenta inlet with a syringe, fluid comes out of all nozzles, so the nozzle plate doesn't appear to be completely clogged.
• Moving the Capping Position actually improved the nozzle test, which makes me think the problem could still be related to capping or pressure.
• After printing continuously for hours, the nozzle test becomes almost perfect.
• After the printer sits overnight or powers itself off, the magenta drops out again.

My questions​

1. Could this still be a capping station alignment / cap slider issue even though the cap seals well?
2. Could a cracked manifold or manifold O-ring create these symptoms?
3. Has anyone seen a DX7 where the head prints perfectly while running but loses half of one color only after sitting idle?
4. Does the mist during the cleaning cycle point more toward a pressure problem, manifold issue or an internal head failure?

I've attached nozzle checks, photos and a video of the cleaning cycle.

PD. In the attached printhead photo, there appears to be a buildup of dried magenta ink on the magenta side of the nozzle plate. It almost looks like the ink is drying or accumulating in that area. I'm not sure if this is normal or if it could indicate poor capping, ink misting during cleaning, or an internal pressure issue.

Does the magenta buildup on the nozzle plate suggest poor capping, ink misting, a manifold issue, or an internal head failure?

Any ideas would be greatly appreciated.

Here's the link for the video:

 

[Smoke_Jaguar]

Head might be delaminated.

 

[cobo_design]

Head might be delaminated.

Thanks for your reply. What makes you think it's delamination instead of a manifold or capping issue? The printer can print perfectly for hours once the magenta recovers, but after sitting idle it drops out again. I'd really appreciate your thoughts.

 

[Smoke_Jaguar]

Capping being off is also very likely as the head will bleed air into the head as the uncapped edge is exposed to air, since the magenta is at the extreme edge of the head. Same case with delamination, though, much more unlikely with a new head but the edges are where strikes do damage first. Follow procedure to align cap and check head for strike damage.

 

[Solventinkjet]

The fact that it's firing strongly and then whimpers out like that tells me it's an ink flow issue. It could be a delamination like Smoke mentioned. Usually with delamination you will see cross-contamination in the nozzle check though. Is magenta bleeding into the cyan or vice versa?

Dampers would normally fix minor ink flow issues but since yours are new, you either might have a defective one or there's some other ink flow issue. Do you see any air in the ink lines above the damper?

 

[cobo_design]

The fact that it's firing strongly and then whimpers out like that tells me it's an ink flow issue. It could be a delamination like Smoke mentioned. Usually with delamination you will see cross-contamination in the nozzle check though. Is magenta bleeding into the cyan or vice versa?

Dampers would normally fix minor ink flow issues but since yours are new, you either might have a defective one or there's some other ink flow issue. Do you see any air in the ink lines above the damper?

No air bubbles at all. The ink lines are completely full. Both dampers are full of ink. Manual syringe flush with cleaning solution flows evenly through the entire magenta nozzle row. Yellow on the same dual-channel damper prints perfectly, but magenta now doesn't fire a single nozzle even after multiple normal Fill Ups and cleanings.

 

[cobo_design]

Capping being off is also very likely as the head will bleed air into the head as the uncapped edge is exposed to air, since the magenta is at the extreme edge of the head. Same case with delamination, though, much more unlikely with a new head but the edges are where strikes do damage first. Follow procedure to align cap and check head for strike damage.

Thanks for the suggestion. I checked the capping alignment carefully.

The cap top leaves a centered seal mark on the head, and when the printer is powered off the head sits firmly on the cap. I don't feel any rocking or uneven pressure when I press on the carriage.

I also checked the ink system:

• Brand new dampers.
• No air bubbles in any ink line.
• The yellow channel that shares the same damper prints perfectly.
• I can manually flush cleaning solution through the magenta channel with a syringe, and it flows evenly through the entire nozzle row.

Initially, a Normal Fill Up would temporarily restore the magenta channel, but now it won't fire a single nozzle even after several Fill Ups and cleanings.

I also don't see any cross-contamination between magenta and cyan in the nozzle check.

At this point, would you still suspect a capping issue, or does this sound more like a failed head (or possibly the slider board)?