Mutoh 1641 SR-Black Printing Green

[Red Alpha]

Hello I have had my printer ( Mutoh 1641 SR) for about 3 years and lately I have noticed that my black looks green especially if its a large area like a banner with a black background. I'm getting a good nozzle check and have played with the color values. I can get a good black if its a small area like 2 feet or less. I replaced the cap top about a month ago because I have was having issues with Cyan and Black dropping out. The drain tube to the waste ink bottle isn't clogged. What else can it be?

 

[Superior_Adam]

what is the color code your sending over for the print. I use either true RGB black 0/0/0 or CMYK 60/40/40/100 for a good true deep rich black. Try one of those and see. A lot of the black is turning greenish it is the color in the art adding too much yellow I believe.

 

[Red Alpha]

what is the color code your sending over for the print. I use either true RGB black 0/0/0 or CMYK 60/40/40/100 for a good true deep rich black. Try one of those and see. A lot of the black is turning greenish it is the color in the art adding too much yellow I believe.

I tried RGB 0/0/0 and CMYK 50/50/50/100 and it seems to be ok for small prints but I printed a couple 4x8 banners with a black background and it looked green

 

[unmateria]

So u begin having a good black but after 2 feets begins a greenish black?
Can u make a new profile using just unidirectional printing instead of bidirectional? (To give the dampers more time to recover?)
Have you re inserted the bags of ink? Sometimes the rubber seal gets damaged doing that and its very little air entering, but enough to ruin the correct pressure

 

[Red Alpha]

So u begin having a good black but after 2 feets begins a greenish black?
Can u make a new profile using just unidirectional printing instead of bidirectional? (To give the dampers more time to recover?)
Have you re inserted the bags of ink? Sometimes the rubber seal gets damaged doing that and its very little air entering, but enough to ruin the correct pressure

Yes about the turning green. Today I changed the input in Flexi to RGB Adobe 1998. I didn't realize that even though I was usine RGB 0-0-0 that flexi was outputting it to a CMYK that wasn't a good black. I forget the values. I shared my computer with tech support form the supplier I bought it from

 

[unmateria]

Dont know flexi, but usually rips doesnt like anything but srgb or fogra39. Anyway if the black is comming good at first and after some feets it changes, usually u have an ink starvation issue. Usually bad pressure from not perfect dampers, a failing cap top seal, a rubber seal on the ink cartdriges/bags or an o-ring failing. If its beginning to fail (just a little air enters the system sometimes), u can debug/try if it is that just printing slower (unidirectional or giving a delay between passes for example). If it prints good, you have an ink starvation issue.

 

[unmateria]

Btw, I made all profiles for my rolls for 1641sr and the black/grays print amazingly good. But I have to adjust all manually because autoadjusts really sucks. Have you tried to use custom adjustments in each user type instead of using auto ones?

 

[Red Alpha]

So after all that I think the problem is with the after market cap tops. This last one I isn't getting a good seal and I think this might be the problem.