Printhead change Mimaki CJV150

[Christirol]

Hello,

I need help!

I recently performed a print head replacement on my Mimaki CJV 150 and switched from 8-color to 4-color ink. I also replaced the waste ink pump, capping station, and dampers.

**Current Issues:**
1. Only 4 channels were flushed during setup; the other 4 remain on standby (no indicator lights, though the display detects them).

2. The initial nozzle test looked semi-okay: CMYK showed, but magenta produced zero droplets. Cleaning cycles did nothing.

3. After removing/reinstalling the damper to inspect, **yellow also stopped working**. Further cleaning left only black ink functional; all other colors vanished.

4. In frustration, I reran the 8C→4C setup. This time, different inks were selected:
- MCK now works (without yellow).
- The other 5 ink channels failed to flush again.


- Did I damage the new print head?
- Could replacing the dampers *again* help?

Thank you so much for any guidance!

 

[Smoke_Jaguar]

When doing 4 color, the cartridges deplete one at a time, allows hot-swapping. You're fine. Just need to install the line bridge connectors that common the like-colors together.

 

[gregjordansr]

Mimaki printers really said, "Congratulations on your new print head, but here’s a side quest of despair." Definitely sounds like air, clogged dampers, or misaligned setup, don’t give up yet

 

[Smoke_Jaguar]

Note how the M is bridged to the other M, Y and Y, C and C, K and K, if those junctions are not installed, you're going to have nothing but headaches.

 

[Neil]

I also replaced the waste ink pump, capping station, and dampers.

There's your problem, I'll bet. Most likely the capping.
When inks drop out like that it's because ink isn't getting pulled through the head when you do a cleaning.

 

[Christirol]

Thank you guys, i did not install the bridges between the tubes, so it just printed whatever tube was filled allready and i got mixed results whenever i changed ink cartridges and i have lots of air in some of the tubes ....

I will test again tomorrow!

 

[Christirol]

Update:

The bridges between each tube were a gamechanger, now i have 6 from 8 colours, sometimes even 6.5 colors...

And i think the blue damper is damaged, because it sucks the air in when blue should be printed

Thanks again, i think i will get all 8 colors in a few days

 

[Smoke_Jaguar]

Yeah, those bridges are critical for four color mode. Ends up being nice having a cartridge buffer on each of the 4 colors. Can run only 4 cartridges and be fine, great for when waiting on ink to come in.

 

[Christirol]

I almost have it guys
Thank you so much, just a tiny bit, just had 30 minutes with the printer today, changed 1 Damper and now it prints like thid with 1 time of ink fueling
I'm 75% sure its just air in my channels.

 

[Smoke_Jaguar]

Manually filling the dampers might help. Tape the ink valves with some masking tape and use a syringe to gently pull ink through the damper port to evacuate all the air. Still going to be a bit of air, but tends to be under 1/3 of the damper level.