Print head drops out completely and comes back

[D3D]

We have a problem where we can do a purge on the white heads and see a nice even flow of ink come off all heads into the tray but when we run a nozzle test an entire head might not be firing. And then with some cleaning work, printing white swatches, etc we will eventually get it back. We have bled the filters a few times. Puzzled by how it seems to flow nicely in the purge but shows nothing in the nozzle test - could this be a voltage issue on an old printhead?

 

[White Haus]

Assuming this is an Arizona................?

 

[D3D]

Assuming this is an Arizona................?

Yes, Arizona 2280

 

[AlsEU]

Have you checked the meniscus vacuum level? Any leaks from the ink system (especially white)?

 

[D3D]

Have you checked the meniscus vacuum level? Any leaks from the ink system (especially white)?

Can't find any leaks. Meniscus pressure seems to be between 15.2-18.4. It was 18.4 when I came in this morning and went as low as 15.2 when a purge was done. Right now it seems to be maintaining around 16.2

 

[AlsEU]

Have you ever done the vacuum operational setpoint adjustment using an external vacuum gauge (the value on the screen may not be exact)? The meniscus vacuum should balance around the specific setpoint in specific time and that needs to be checked from time to time.

 

[D3D]

Have you ever done the vacuum operational setpoint adjustment using an external vacuum gauge (the value on the screen may not be exact)? The meniscus vacuum should balance around the specific setpoint in specific time and that needs to be checked from time to time.

Sounds like this requires a specific piece of equipment and a service key? If the meniscus vacuum is the reason the head drops out, what are you expecting to see with the gauge, or if the screen is accurate what values would you expect?

 

[AlsEU]

To calibrate the meniscus vacuum set point you need a service key and a vacuum gauge connected to the vacuum tube. The gauge shows how the meniscus vacuum value changes (in fact is not a single value, it is increasing and decreasing around the specific set point in a specific time. Both set point and time have to be calibrated properly). And sometimes value shown on the screen is different than this of the gauge (according to the service procedure only the gauge value should be used for calibration), because the screen shows only one value, not changes.

 

[D3D]

So we might get a tech out here to run through this but I would like to have a sense if improper vacuum values are the only (or even main) thing that could result in our problem. Is this the ONE THING we should be focused on in our troubleshooting?

 

[AlsEU]

If the problem is visible only in the W channel, it means it's somewhere in this channel. When the nozzles are gone, is there any ink on the nozzle plates of the head? Do you see any ink in the vacuum tubing above the heads? Is any ink spilt under heads after the long idle time?

 

[D3D]

If the problem is visible only in the W channel, it means it's somewhere in this channel. When the nozzles are gone, is there any ink on the nozzle plates of the head? Do you see any ink in the vacuum tubing above the heads? Is any ink spilt under heads after the long idle time?

There is ink on the nozzle plates, in fact I can get a good looking purge. Which I think rules out the nozzles being clogged.

 

[johnnysigns]

Is there air trapped in the head/lines at all?

 

[AlsEU]

There is ink on the nozzle plates, in fact I can get a good looking purge. Which I think rules out the nozzles being clogged.

White ink is the heaviest ink of all colours. Maybe you have a meniscus vacuum too weak and it can't keep the ink inside the heads.

 

[D3D]

Is there air trapped in the head/lines at all?

As a means of troubleshooting I have been bleeding air every morning. Since then I have not had the head go out completely, I just struggle with more ordinary groups of missing nozzles that I can eventually recover. Might be multiple things going on, perhaps air in the line + old print heads. Not sure about the meniscus vacuum being too weak, it doesn't drip ink or anything.

 

[czbhu]

We had the same issue on a flatbed. It caused by a small hole on the air tube. So is just changed it and it is fine.