Need Help UJF-6042 MkII Head Temp. Control

[McKinneyPrintingCompany]

Unfortunately, I don't have a great answer for you. I saw the same issue in regards to my temperatures appearing to always be in range and the problem growing progressively worse until an override was required for almost every print, (with the only consistent exception being that it always worked on the first print after a restart of the machine). I replaced the circulation pump, but, it only had a marginal and temporary impact on the issue which probably just coincided with the intermittent nature of the problem. I then replaced the heater and the problem became less frequent, but, I still saw it on an intermittent basis. I then flushed the coolant lines completely about half a dozen times, which, also seemed to have some impact as eventually the problem disappeared altogether.

Since then I've suspected it could have been two problems - an intermittently failing heater and a problem with the coolant loop itself, (potentially with trapped air), that when both started to occur at the same time, resulted in the eventual need to override regularly. That said, the temperatures appearing as if they were always in always in range was probably the most puzzling thing. I also could not identify any external factors like the room temperature and humidity being an issue as they have always been very consistent.

In regards to the machine hanging during the auto-startup and circulation process - I never had that happen. Do you have to hard power-off the machine to get it out of the circulation state?

If your issue is temperature related only, I would personally start with flushing the coolant loop a number of times and doing everything you can to ensure no air is trapped somewhere where you can't see. You might then consider replacing the heater and / or circulation pump as, (insofar as I can figure), they are the next highest provable and lowest cost components that might fix the problem. For my issue, the only other thing I could think of after that was the mainboard which is something I wanted to avoid altogether for obvious reasons.

 

[Biggady]

Looking at those temps, I'm guessing that you don't use your primer too often and that some of the nozzles have become blocked - the head will struggle to heat up if this is the case.

If you are able to clear the head (try using the PR200 cleaning solution if you haven't already) you should see the problem resolve itself, if not you are able to change the target temperature for that head, but this will unfortunately accelerate its demise.

 

[CloverCustom]

Thank you, that gives me at least some hope that I can get this to go away. I will try flushing out the water lines and see what happens.

When it does get hung up on wake up cycles, most times I can just press end for a second or two and it will then move the bed forward and go to the main menu screen.
Sometimes pressing end does nothing and the only thing I can do to get it out of that is the main power switch on the side.

 

[TD Digital]

You either have an issue with the hot water heater or the pump. If the tech who installed the machine didn't prime the pump prior to turning it on that can put tremendous stress on the pump itself. If you constantly get the head temp please wait and you are certain that there isn't an over abundance of air in the system then you probably need the hot water heater or pump. I've replaced over a dozen how water heaters over the last few years because of this.

 

[CloverCustom]

McKinneyPrintingCompany , How did you go about making sure the lines were flushed?
I am going to give that a try this weekend.

 

[McKinneyPrintingCompany]

McKinneyPrintingCompany , How did you go about making sure the lines were flushed?
I am going to give that a try this weekend.

Sorry for the delay.

I first stopped the pump via the standard fill-up process and filled the entire loop to as about as full as I could get it. Since I had the inside cover off exposing all the lines, pump, heater and reservoir, I could tell about how full it was, so, I filled it up until I could see coolant coming back around to the output. I then drew out from the output about 120cc's and put it back into the input once I was sure the syringe was completely clear of any air / air bubbles. I then started up the pump again and let it run a bit. I repeated the process of drawing-out 120 cc's, removing any air from the syringe and refilling it again about 10 times, (each time stopping and starting the pump through the water fill-up menu).

I know my process was not really by the book and it's possible some parts are unnecessary, but, I was not having luck following the standard procedure and I wanted to be absolutely certain I had all the air out.

I hope this helps.

 

[Quicksign]

You either have an issue with the hot water heater or the pump. If the tech who installed the machine didn't prime the pump prior to turning it on that can put tremendous stress on the pump itself. If you constantly get the head temp please wait and you are certain that there isn't an over abundance of air in the system then you probably need the hot water heater or pump. I've replaced over a dozen how water heaters over the last few years because of this.

I still have problems with my temps, I have installed a new pump , which is working fine and also installed a new water heater but this does not seem to be getting hot or even warm, there doesn't seem to be much air in the system , so any suggestions as to why the heater is not working, any help would be appreciated.

 

[McKinneyPrintingCompany]

I still have problems with my temps, I have installed a new pump , which is working fine and also installed a new water heater but this does not seem to be getting hot or even warm, there doesn't seem to be much air in the system , so any suggestions as to why the heater is not working, any help would be appreciated.

When you touch the lines or the heater unit itself after operation, does it feel warm at all. Do you think it's doing anything?

 

[Quicksign]

When you touch the lines or the heater unit itself after operation, does it feel warm at all. Do you think it's doing anything?

Hi,
No the heater or the lines are not even warm.
It doesn’t seem to heating up at all.

 

[McKinneyPrintingCompany]

I think your right - it doesn't sound like it's working. I could always tell especially when touching the heating unit itself that it was putting out some kind of heat. You might check your power connections to the heater. One thing I noticed when changing mine was that it could be really easy to miss one of the connections, but, that is just a guess outside of saying that unit you got is bad.

 

[lubo1972]

Hi, any update about heating problem? We have it from long time and now machine also stuck on circulation forever. After weekend we found a lot of missing nozzles on white and yellow.

 

[Smoke_Jaguar]

Circulation is just to keep the white ink mixed up, are you having a temperature issue or circulation issues? Or maybe both?

 

[lubo1972]

We have both problems. Head Temp Contrl. is take forever until we press Enter. Other problem, when machine is at sleep and start Flushing, Circulation or other cleaning process it never turn off after that or it takes hours!

 

[Smoke_Jaguar]

Temp control takes a while in general, but you might want to flush and replace all the antifreeze/coolant. Make sure to use propylene glycol, NOT ethylene glycol and not RV antifreeze (which is mostly ethanol these days). You can adjust intervals for cleaning/flushing cycles as well, but note that auto maintenance, when working properly, only uses trivial amounts of ink.

 

[lubo1972]

I flushed at least 600ml of cooling mixture and put new one. I am using Mimaki's antifreeze diluted with water 1:2. New problem just found today, because I am not main operator of the machine! Machine didn't make circulation over the day when we print! Before printer make circulation every 2-3 hours, now - NOTHING! There is something wrong with all cleaning procedures! Technician don't have any idea what is wrong!

 

[Smoke_Jaguar]

I wonder if circulation got turned off, seen people do that before to stop printer from 'wasting ink'.

 

[lubo1972]

No, it doesn't turned off. just machine don't do it! When printer is in sleep mode it makes circulation but didn't turn off after that! Same with FLUSHING and other cleaning cycles. Something is wrong with some sensor or mainboard or who knows! technician don't have any clue about that problem! Thing goes very bad with white because of no circulation at all over the day!

 

[Smoke_Jaguar]

Yeah, circulation is key with white inks. Do the circulation pumps get hot or do they seem to be bound up? Sometimes the tubing in the peristaltic pumps gets a bit too stretchy and can completely jam up the works. Doesn't help when they're running all 4 pump bodies on one poor stepper motor.

 

[lubo1972]

Now circulation works time to time. I hear knocking sound of pumps. But problem with not turning off is same. We decide to change machine for next model. Hope that Mimaki fixed those problems.

 

[patuga]

I have an 6042 Mk2e installed in 2021 (one of the first ones installed in our country) and have a similar same issue. In my case, one of the channels is 10ºC cooler than the others, and therefore print doesn't start until i press enter. From what the technician told me, some printheads have problems with their thermistors, and in order to fix this issue the print head needs to be replaced. if the problem is detected within 18 months after installation, they will replace it for free. otherwise, we're out of luck.
Problem seems to have been fixed with a recent revision of the heads. but still, it sucks that mimaki doesn't honor this issue, even though they detected it and just kept quiet about it.

In our case, printer works fine, but there are people who are not so lucky. if the temperature goes to crazy values like +100ºC, printer will just refuse to print with an error code, and printhead needs to be replaced, even if there's nothing wrong with it.

i'm hoping there's a hidden option on the maintenance menus that allows you to configure an offset for the temperature to solve this issue.