Stylus Pro 4880 Field Repair Guide 1/17/08
Random Nozzles Printer Component, Software Item, LCD Display, Printer Button  Page 127.
Random Nozzles
Note: Random Nozzles refers to Nozzles that fire when they are not commanded to.
Random Nozzle firing is caused by 1 of 4 components
•Head Cables
•Print Head
•Main Board
•Power Supply
Head Cable
Inspect the Head Cables for worn insulation. Place tape over the worn area or replace the Cable.
Print Head or Main Board
If the random Nozzle firing is caused by serial communication problems between the Main Board and the Print 
Head, the frequency of the random Nozzle firing changes when the printing resolution is changed. If changing the 
printing resolution affects the random Nozzle firing, change the Main Board and the Print Head. Change them one 
at a time in any order. Test between each change.
Power Supply
Sometimes (very rare) a noisy Power Supply causes random Nozzle firing.