Need Help UJF-6042 MkII Head Temp. Control

[Biggady]

Hi,

Having a problem with our UJF-6042 MkII where it seems unable to get the heads up to temperature. Unless you override it by pressing 'enter' the machine won't print and will just display the message 'Head Temp. Control Please Wait...'.

Does anyone know what temperature the heads need to be before it will start printing? When I check the head temps they are getting up to between 46ºC and 53ºC.

I've drained and refilled the coolant just to check it wasn't due to the wrong ratio of coolant and water. The heater seems to be working correctly, and the water pump is definitely pumping - hard to tell if it's pumping as it should but seems to be the kind of flow I'd expect.

If anyone has any ideas they'd be much appreciated!

Also, a bit of a long shot if anyone knows where I could get hold of a service manual for this machine that too would be much appreciated!

Cheers.

 

[Solventinkjet]

The coolant is for the LED lamps not the head but it's good you checked it just in case. The only thing I can think of is the room temperature is so cold that the head can't heat up to the proper temp, unlikely this time of year, or the head heater is just failing to heat up properly. You only get an error when the head temp gets below -10C or over 80C. The tech manual, which I'm not allowed to give out sorry, only mentions this range and doesn't say what temp the head wants to be at to start printing. Did this problem just happen out of the blue?

 

[Biggady]

Hi

Thanks for the reply - much appreciated.

I thought on the MkII the water was used to warm the heads, and the UV unit was air cooled. Why is there a water heater if this isn't the case?

The problem has gradually occurred over a couple of weeks - at first it would just take longer than usual to start printing, but now it's got the point where it won't commence printing no matter how long it's left.

 

[Solventinkjet]

You're right. I keep mixing this model up with another one. I would suspect your water heater isn't heating up properly. Probably a bad heating element. The printer doesn't seem to have a timeout function so if it never reaches the proper temp, it just tries and tries forever.

 

[TD Digital]

This is normal and is usually caused by air. Put a syringe on the out port and pull a few syringes full to eliminate any air. I normally add coolant until I see it start to flow from the overflow line. Turn on and repeat. If it continues to happen then your hot water heater is probably starting to fail. This happens periodically on several of our MKII printers.

 

[Biggady]

Cheers TD Digital - I did manage to resolve the issue eventually, but I hadn't really been sure what had actually solved it.
One of the things I did do though (amongst other things) was what you suggest, by pulling coolant from the out and then putting it back in the in (minus any air) - it's good to know exactly what to do when it happens again, so thanks a lot for the help.

 

[Quicksign]

Hi .
I have the same problem as Biggady, on my Mimaki 6042 Mk II, which is nearly 3 years old
i have drained the tank twice now and refilled with the correct 2-1 mixture of de-ionised water and anti-freeze but still get the same message 'Head Temp. Control Please Wait...'.
I can override this by pressing enter and then the print quality is pretty good.
The company i bought the printer from says it could be the water pump or the head has gone but is it possible it's the water heater it's self as it is not getting hot.
Any help would be much appreciated.

 

[Biggady]

Hi Quicksign
I suspect it could be your heater - it definitely should be giving off a fair bit of heat, definitely enough that it should be obvious if it's on or not.
Probably others on here that would know if there are any other reasons as to why it's not turning on though.

 

[McKinneyPrintingCompany]

Hi - I'm having the exact same problem. Not sure if it's the pump or the heater, (or something else). I've listed my machines temps below, but, I unfortunately have no documentation as to what the ranges should actually be:

Head 1a = 45 C
Head 1b = 49 C
Head 2a = 49 C
Head 2b = 49 C

Water Heater = 67 C

LCD = 29 C

LED 4 = 29 C
LED 3 = 26 C
LED 2 = 26 C
LED 1 = 24 C

UV DRV 1_3 = 37 C
UV DRV 1_2 = 36 C
UV DRV 1_1 = 36 C

I replaced the anti-freeze with the correct 1:2 mixture as others have done, however, it still takes a long time to clear the 'Head Temp. Control' state. Most of the time I have to hit the enter key to get it to actually print, but, the prints themselves proceed without any issues except when doing multiple layers. I'm guessing between layers it's trying to maintain the temperature again which is causing long delays.

Was your issue the heater or the pump and were your temperatures similar?

Thank you in advance for your reply!

 

[Pablo583]

You have an air issue and the coolant isn’t circulating.

 

[McKinneyPrintingCompany]

Thanks for your reply. I thought the same as well and have been trying to take air out from the output port, but, so far nothing has changed. I also opened up the inside panel to expose all the tubing and at least based on what I can see, coolant is flowing. That said, I'm not ruling out air as the problem, but, so far I've not been able to find out where it is in the loop if it does exist.

 

[Quicksign]

Hi,
Your temperatures don't seem to bad,
According to my Mimaki Engineer, Heads 1-4 should be around 48 degrees and the Hot water Temp should be around 60 degrees..

The heads on my printer were around 28-29 and water heater around 29.

I have changed the coolant and taken air out as much as i can and i still have a problem

I have ordered a new Pump and water heater and just waiting for the heater to come before i change both and hopefully this will sort it out.

 

[McKinneyPrintingCompany]

I did the same today and ordered a new pump via overnight shipping. Hopefully it will get here quickly and that will fix the issue, but, I'll let you know what happens.

- Thanks

 

[McKinneyPrintingCompany]

So, I received and installed the new pump a few days ago and have seen some improvement, but, occasionally it still does get stuck in the 'Head Temp. Control' state for a short time. That said, the issue has improved and the temperatures always look within range, (even when occasionally hanging), so, I'll probably wait for a better indication of the problem before ordering anymore parts.

 

[McKinneyPrintingCompany]

It seems my issue has changed in consistency to hanging now each time I try to print. With that said, there are two exceptions. Every time after a reboot, it will print after the expected, (normal), Head Temp Control time without the need for an override. Any subsequent prints, (regardless of the time that has elapsed after the initial post-reboot print), always hang.

I've also recently noticed that the simple act of cycling through the 'Water FillUp' menu, (without actually doing a water fill-up), seems to result in the same ability of the machine to start the printing process without an override. Unfortunately, any subsequent prints, (including the same print, but, subsequent layer), results in a hang. I can hear that it stops the water pump when I cycle through the Water Fill-Up menu, but, since I replaced this already, I'm guessing there is some other conditional that's being cleared allowing it to print one-time as normal.

As such, given I had no other obvious ideas, I went ahead and ordered / installed a new Heater Assy. Unfortunately, I have to report the issue is still exactly the same.

When I go back and look at the temps after it hangs, everything appears to be in the proper operational range:

Head 1a = 45 C
Head 1b = 49 C
Head 2a = 49 C
Head 2b = 50 C
Head 3a = 50 C
Head 3b = 50 C
Head 4a = 49 C
Head 4b = 49 C

Water Heater = 61 C

LCD = 29 C

LED 1 = 25 C
LED 2 = 26 C
LED 3 = 26 C
LED 4 = 26 C

UV DRV 1_2 = 35 C
UV DRV 1_2 = 35 C
UV DRV 1_3 = 35 C

Currently I'm thinking there's either a problem with the way the machine is interpreting the temperatures, (which could indicate a PCB problem), or, there is condition, (other than the temperatures), not being met that is necessary for the 'Head Temp Control' state to be cleared. Coming from an engineering background, I find this very frustrating to troubleshoot without access to any kind of real technical documentation and the process of just guessing at replacing parts is getting expensive. If anyone has access to any technical documentation related to this issue that they could share - I would greatly appreciate it.

Thanks!

 

[dudeinthemoon]

You definitely overthinking the issue. If you already changed coolant and I hope you did recommended proportions (1 coolant + 2 distilled water) and filled at least 450ml, removing air and adding little more liquid after there was nothing left to do with the printer. Now the main thing its the room temperature, try to increase it a little, just for experiment. I think you'll be surprised. But don't listen to me, try to investigate, when it was working normal last time? Try to remember what was changed since then? It might be just opened window or something changing the room temperature. It is a common problem, and in all cases it was just the temperature lower than usual. It happens usually on summer when windows are open or AC is running

 

[dudeinthemoon]

And you always can skip head heating just pushing the enter button

 

[McKinneyPrintingCompany]

And you always can skip head heating just pushing the enter button

Thanks - I think that's what I'll have to accept doing for now. I generally make sure its heats up the first time by checking the temperatures and then override the process for subsequent prints.

 

[McKinneyPrintingCompany]

You definitely overthinking the issue. If you already changed coolant and I hope you did recommended proportions (1 coolant + 2 distilled water) and filled at least 450ml, removing air and adding little more liquid after there was nothing left to do with the printer. Now the main thing its the room temperature, try to increase it a little, just for experiment. I think you'll be surprised. But don't listen to me, try to investigate, when it was working normal last time? Try to remember what was changed since then? It might be just opened window or something changing the room temperature. It is a common problem, and in all cases it was just the temperature lower than usual. It happens usually on summer when windows are open or AC is running

Your probably right about my overthinking as it still could be something very simple. That said, my environment is pretty well fixed at 72 F and 45% humidity 24x7 and nothing else environmentally has changed that I can tell in the three years since we've had the machine. We have other printers that are sensitive to environmental changes as well, but, none have had any issues up to this point.


We upgraded the firmware in our last round of troubleshooting with the vendor, but, there was no change to the issue. I guess for the time being it will remain a mystery until something else happens that points to the cause.

 

[CloverCustom]

I am experiencing the same issue now. Head temp control used to just take longer than normal but now it will stay there forever until I override.

If I leave it in head temp control for about 10 minutes and then check temperatures I get this.

1A - 43 deg
1B - 48 deg
2A - 50 deg
2B - 50 deg
3A - 50 deg
3B - 50 deg
4A - 50 deg
4B - 50 deg

Water heater - 70 deg

The other issue I am having is ever since I started getting this head temp control that won't go away, the machine will hang during it routine circulation wake ups during the night.
The machine will wake up and complete a circulation as normal but it will not turn off afterwards. The screen will stay flashing circulation for hours.

My thought is during this process of the wake up, it completes the circulation but it also trying to head up head 1 to proper temperature but since it doesn't heat up then it just sits there waiting forever.
Like others, upgrading the firmware did not change the issue.

McKinneyPrintingCompany Quicksign Were you able to get this resolved?