HP 250C - Manual (Page 191)

8Ć57 Troubleshooting C4699Ć90000
Banding
Symptoms
Random dark or light bands in area fills. (PrintĆQuality Plot ' page 8Ć56,
1. - Area Fills
, and
the offsetĆswath lines on the right of the plot.) (See also ' User's Guide, chapter 4.)
Cartridge Fault
D A nozzle is blocked or faulty and is not firing inkĆdrops. (PĆQ Plot '
2. - Nozzle Checkout
.)
D The ink drops of one nozzle are of smaller volume than those of the other nozzles.
D A nozzle's ink drop volume varies while plotting.
D A nozzle's ink drops are misdirected:
- Defect in manufacture of cartridge
- Dirt or debris on the nozzle plate
- Ink puddling on the nozzle plate
D An electrical contact is misaligned or damaged on the cartridge, so that it doesn't make
correct contact with the circuit on the carriage. (See ' page 8Ć39, w Carriage Test.)
Plotter Fault
D Incorrect swathĆadvance angle of the drive roller. This could be caused by a
- Faulty roller (irregular roller radius / defective bearings)
- MediaĆaxis inaccuracy (defective media motor or driver circuit / calibration lost)
D An electrical contact is faulty in one of the plotter cartridge chutes, so that it doesn't
make correct contact with the circuit on the cartridge. (See ' page 8Ć39, w Carriage Test.)
D Nozzles touch the service station, thus causing puddling to occur on the printĆhead.
D Some of the small slots on the encoder strip are damaged. Therefore the plotter cannot
position the carriage correctly during cartridge servicing.
D Cartridges are misaligned with respect to each other.
D Calibration values lost or incorrect.
Media Fault
Some types of media have a coating that prevents them getting wet" from the ink drop. The
ink doesn't spread out sufficiently around the point where the dot is placed.
Banding may not occur on some poorĆquality media, where it is counteracted by another
problem: large dot gain. This is where the ink spreads out excessively on the media around
the desired dot position. To accurately test for banding, use HP polyester inkjet film.
Solutions
One or more of the following actions may be appropriate to solve a banding problem:
D Prime/clean cartridges. D Perform accuracy calibration
D Reseat/replace cartridges. D Reseat cartridge caps in service station.
D Perform cartridge alignment. D Replace encoder strip.