HP Designjet T Series — Service Manual 1-23
Print quality troubleshooting
Nozzle Health
The print contains three separate parts.
a The Variable Frequency Nozzle health plot with odd/even nozzles
separation. This is used to detect misdirected nozzles, weak nozzles, or
nozzles not working correctly at all frequencies.
b Inspector measuring tool test plot.
Test b should NOT be used by Service Engineers.
c Nozzle Print Test which is also part of the Image Quality Service Plot.
This test is designed to check that the Printhead nozzles print correctly.
The test prints out every single nozzle of each Printhead. No error hiding
or Printhead Alignment algorithm is applied. For each Printhead, you can
see both the adjacent and the consecutive nozzles.
This is what you would see in the Nozzle Print Test part if there are
nozzles not printing correctly:
1 On the right of each Printhead Nozzle test, there is a series of numbered
stepped diagonal lines. If one or more of the nozzles are malfunctioning or
mis-positioned, you will see that the stepped lines are broken or misdirected
in one or more places.
2 On the left of each Printhead Nozzle test, there is a series of horizontal
straight lines. If one or more nozzles are misdirected there will be unequal
spaces between the corresponding lines.
Corrective Action for Nozzle Defects
If the printer has nozzle defects, it does not mean that you will not get
perfect print quality results. The printer has automatic procedures to hide
many nozzle defects.
1 Recover the Printheads using the option through the Front Panel (Main
menu/Image quality maintenance/clean printheads).
2 Reprint the Nozzle Print test to check that the defective nozzles have been
corrected.
3 If the problem continues, replace the defective Printhead.
a
b c
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