Need Help JFX200-2513 Starvation of Both Heads? No Errors

[bgraphics]

I've searched for similar issues with this printer on Signs101 and have turned up nothing. Double CMYK configuration. After a clean test draw, we begin printing and after several passes on a photo-realistic print (only just a few passes on a solid color such as C or M or Y or K), nozzles start to drop out. We see a white lines/streakiness. Stopping the print and doing a test draw, we see which nozzles are out - different every time. If we let the printer rest a few minutes and do another test draw (without cleaning OR wiping), test draw is fine again.

• No subtank errors (though we have replaced 1 subtank when we first thought it was just a cyan issue)
• No pressure errors (we see relatively stable pressure and have adjusted negative and positive pressures each day for the past month as we have tried to diagnose our problem
• Replaced all vent filters to both heads
• Raised environmental humidity to 41 from 35 when we thought this could have been an issue - but again, test draw is beautiful after machine just sitting for a while.
• Had our 2nd-ever water lack error on day 2 of the problem and filled up accordingly
• Traced the pressure lines and don't see anything abnormal
• Examined air purge ports and everything seems normal
• Unplugged and replugged machine
• Said some very intense prayers (and have said other things)
• Printed on Foamboard and Corrugated plastic w/ same results
• Looked at subtank [HASHTAG]#TEST[/HASHTAG] readouts and have only seen ---/---/---etc.

How do printheads tell the subtanks that they need ink? or do they? Haven't tried running the machine without subtank guards to witness what is actually happening during printing.

 

[Solventinkjet]

Did you run an air purge? Usually that's the first thing I do if there is drop out. I would also try to figure out how long it's been since you replaced the primary filters (in the ink supply box). Mimaki recommends replacing them once per year.

The sub tanks have magnetic sensors on the outside that reads the magnetic floats inside the sub tank. Each sensor has 3 sections; low, high, and overflow. When the sensor reads low, it tells the printer to fill the sub tank. When it reads high, it tells the printer to stop. When it reads overflow, it gives you an error and stops the machine from doing anything to avoid leaks. When you see ---/---/--- it means the sub tank has ink in it but is not low or high enough to trip the sensor. Essentially, all is fine. You can probably rule out the sub tanks.

I have seen a couple of machine were the pressure was able to be adjusted but it was too variable to work properly. When you adjust it, it should stay fairly steady. If it's jumping all over the place, there could be an issue there. But do the air purge first. A lot of the time, as time goes by, little bits of air get in and it build up over time which can cause flow issues. Then change the primary filters if they are older than a year.

 

[bgraphics]

Did you run an air purge? Usually that's the first thing I do if there is drop out. I would also try to figure out how long it's been since you replaced the primary filters (in the ink supply box). Mimaki recommends replacing them once per year.

The sub tanks have magnetic sensors on the outside that reads the magnetic floats inside the sub tank. Each sensor has 3 sections; low, high, and overflow. When the sensor reads low, it tells the printer to fill the sub tank. When it reads high, it tells the printer to stop. When it reads overflow, it gives you an error and stops the machine from doing anything to avoid leaks. When you see ---/---/--- it means the sub tank has ink in it but is not low or high enough to trip the sensor. Essentially, all is fine. You can probably rule out the sub tanks.

I have seen a couple of machine were the pressure was able to be adjusted but it was too variable to work properly. When you adjust it, it should stay fairly steady. If it's jumping all over the place, there could be an issue there. But do the air purge first. A lot of the time, as time goes by, little bits of air get in and it build up over time which can cause flow issues. Then change the primary filters if they are older than a year.

The machine is definitely older than a year and I haven't replaced those. Is it likely that they all would be exhibiting this problem at the same time?
I have run air purges on several occasions (on cyan only when we thought it was a Cyan issue). I will try the other channels. Yes, we did pull lots of air out at the time. It never fixed the cyan problem when we were running solid blocks of cyan.
Regarding the negative pressure, it seems to be maintaining pretty steadily and I would not say it is jumping around. Positive pressure definitely jumps around.

 

[Solventinkjet]

The machine is definitely older than a year and I haven't replaced those. Is it likely that they all would be exhibiting this problem at the same time?
I have run air purges on several occasions (on cyan only when we thought it was a Cyan issue). I will try the other channels. Yes, we did pull lots of air out at the time. It never fixed the cyan problem when we were running solid blocks of cyan.
Regarding the negative pressure, it seems to be maintaining pretty steadily and I would not say it is jumping around. Positive pressure definitely jumps around.

It would a pretty big coincidence if all the filters started failing at the same time. Normally you would see one or two channels have issues that tend to get worse as time goes by.

I would definitely run the air purge on all the channels. What should happen is mostly air comes out, then ink and bubbles, and then once the last bubble you see is about 2 feet down the line, the air will be purged. If that's not happening, there's probably an air leak somewhere. The fact that the positive pressure is jumping around could also be a sign of that. When running an air purge it uses the positive pressure. My guess is the negative pressure is working which fills up the sub tank but the positive pressure is failing which is used during the air purge and while printing to keep consistent ink flow to the head. Check all of your air and ink tube connections and make sure they are tight.

 

[Volkan CANSU]

Baza böyle bir hata geldi negatif pozitif basınç ayarları filtre değişimi kafa değişimi valf değişimi yapılmasına rağmen sorun düzelmemişti. Kep ayarlarını yeniden yapılınca sorun düzelmiş ti. Kep ayarlarını tekrar kontrol etmenizi rica ederim

 

[bgraphics]

Heard back from Mimaki USA... could be “the 2/3 way air valve that sits above the heads. There is a diaphragm in it that can fail and cause this issue, but will most likely give an error message but not always.” Confirmed there is only one that controls both heads. Seems to fit the scenario so passed this on to local tech since I feel I’m starting to get beyond my pay grade.

 

[bgraphics]

Wasn't the 2/3 way air valve. Replaced both subtanks - doesn't seem to the problem.