The meniscus vacuum is among the most important elements for a good working DOD inkjet.
The meniscus vacuum just holds up enough the ink so that it does not drop out of the piezo.
If you have to little vacuum the ink will sag or even drop out of the head. If you have too much the vacuum, the ink will sucked in. In both circumstances you will experience jetouts.
There is a vacuum pump that is turned with a pulse width modulation (PWM output) signal that should be between 30 and 35.
How do you see that ? here you see the actual value and here the setpoint. This is the PWM
You get this menu by pressing and selecting PID Debug from the Main Menu, where you also see the Vac
So, turn the relief valve screw until PWM Output is 33 (note that the reading is in hex and is max. 40). Why 33 ? because you need some slack to go up and down.
How do you set the SetPoint ?
From the Main Menu, press Setup, enter the password (1-3-2-4), and select Vac setting
The vacuum sensors are a bit different; one has to enter an offset when building an inkjet. Measure it with a manometer and enter the value here:
In Setup/Vacuum Offset in the inkjet.
You will see in the online menu of the controller the actual and setpoint of the meniscus