Controller Error
4.3 TROUBLESHOOTING GUIDE
Remove the NVRAM from the original engine control board and install it on the new one when you replace the engine control board.
4.3.1 BLANK PRINT
Symptom Possible cause Necessary actions
Defective LDU Replace the LDU.
Defective PCU Replace the PCU.
Defective transfer belt unit Replace the transfer belt unit.
Incorrect action of transfer roller
Check the guide and the transfer roller.
Defective high voltage supply board
Replace high voltage supply board 1 or 2.
No image is printed.
Defective engine board (EGB)
Replace the engine board (EGB).
4.3.2 ALL-BLACK PRINT
Symptom Possible cause Necessary actions
Incorrectly installed PCU Install the PCU correctly.
Defective PCU Replace the PCU.
Defective high voltage supply board
Replace high voltage supply board 1 or 2.
Defective LDU Replace the LDU.
Defective engine board (EGB)
Replace the engine board (EGB).
All the paper is black.
Defective main board Replace the main board.
Troubleshooting Guide
SM 4-45 G190 Trouble- shooting
4.3.3 MISSING CMY COLOR
Symptom Possible cause Necessary actions
Defective PCU Replace the PCU.
Loose connection between printer cartridge and engine board (EGB)
Replace the drum positioning cover. (See
‘Replacement and Adjustment – Electrical Components – Electrical Board Unit’.)
Transfer belt not contacting
PCU Check the belt tension unit.
Defective the color OPC motor
Replace the color OPC motor.
C, M, or Y is missing.
Defective engine board (EGB)
Replace the engine board (EGB).
4.3.4 LIGHT PRINT
Symptom Possible cause Necessary actions
Loose connection between transfer roller and high voltage supply unit
Check the connection between the transfer roller and the high voltage supply unit.
Dust in the laser beam path Clean the laser beam path.
Transfer belt not contacting
PCU Check the transfer unit.
Defective PCU Replace the PCU.
Defective transfer roller Repair the transfer roller.
Defective fusing unit Replace the fusing unit.
Printed images are too weak.
Defective engine board (EGB)
Replace the engine board (EGB).
Troubleshooting Guide
SM 4-47 G190 Trouble- shooting
4.3.5 REPEATED SPOTS OR LINES ON PRINTS
The same spots or lines appear at regular intervals.
Interval Possible cause Necessary actions
At intervals of 35.0 mm
(1.38 inches) Defective charge roller Replace the PCU.
At intervals of 35.8 mm (1.41 inches)
Defective OPC cleaning brush
roller Replace the PCU.
At intervals of 40.5 mm
(1.59 inches) Defective belt entrance roller Replace the transfer belt unit.
At intervals of 41.1 mm
(1.62 inches) Defective belt transfer roller Replace the transfer belt unit.
At intervals of 47.1 mm
(1.86 inches) Defective toner mixing auger Replace the PCU.
At intervals of 56.5 mm
(2.23 inches) Defective development roller Replace the PCU At intervals of 72.8 mm
(2.87 inches) Defective belt tension roller Replace the transfer belt unit.
At intervals of 82.2 mm (3.24 inches)
Defective transfer belt drive roller
Replace the transfer belt unit.
At intervals of 82.5 mm
(3.25 inches) Defective transfer roller Replace the transfer roller.
At intervals of 94.2 mm (3.71 inches)
Defective OPC drum or pressure roller
Replace the PCU or the fusing unit
At intervals of 141.4 mm
(5.57 inches) Defective fusing belt Replace the fusing unit.
4.3.6 DARK VERTICAL LINE ON PRINTS
Symptom Possible cause Necessary actions A dark line appears. The line
is parallel to the paper feed direction of one CMY color.
Defective PCU Replace the PCU.
Dust in the laser beam path Clean the laser beam path.
Defective transfer belt unit Replace the transfer belt unit.
A dark line appears. The line is parallel to the paper feed direction of any color (not C, M, or Y).
Defective fusing unit Replace the fusing unit.
4.3.7 WHITE HORIZONTAL LINES OR BANDS
Symptom Possible cause Necessary actions
Defective PCU Replace the PCU.
Defective transfer belt unit Replace the transfer belt unit.
White lines or bands appear in images of all toner colors.
Defective transfer roller Replace the transfer roller.
Troubleshooting Guide
SM 4-49 G190 Trouble- shooting
4.3.8 MISSING PARTS OF IMAGES
Symptom Possible cause Necessary actions
Defective PCU Replace the PCU.
Defective transfer belt unit Replace the transfer belt unit.
Defective transfer roller Replace the transfer roller.
Some parts of images are missing.
Defective fusing unit Replace the fusing unit.
4.3.9 DIRTY BACKGROUND
Symptom Possible cause Necessary actions
Backgrounds of one CMYK
color are too dense. Defective PCU Replace the PCU.
Backgrounds of more than one CMYK are too
dense.color
Defective high voltage supply board
Replace the high voltage supply board (1 or 2).
4.3.10 PARTIAL CMY COLOR DOTS
Symptom Possible cause Necessary actions
Defective PCU Replace the PCU.
Defective transfer belt unit Replace the transfer belt unit.
Unexpected dots of the same color appear at irregular intervals.
Defective fusing unit Replace the fusing unit.
4.3.11 DARK IRREGULAR STREAKS ON PRINTS
Symptom Possible cause Necessary actions
Unexpected streaks appear
at irregular intervals. Defective transfer belt Replace the transfer belt unit.
4.3.12 CMY COLOR IRREGULAR STREAKS
Symptom Possible cause Necessary actions
Defective PCU Replace the PCU.
Unexpected streaks of the same color appear at
irregular intervals. Defective transfer belt unit Replace the transfer belt unit.
4.3.13 GHOSTING
Symptom Possible cause Necessary actions
Defective PCU Replace the PCU.
The same or similar image appears two or more times.
They get weaker and weaker.
Defective transfer unit Replace the transfer unit.
Troubleshooting Guide
SM 4-51 G190 Trouble- shooting
4.3.14 UNFUSED OR PARTIALLY FUSED PRINTS
Symptom Possible cause Necessary actions
Non-standard paper in use Use recommended paper.
Incorrect media type mode Select an appropriate media mode.
Some parts of images are not fused very well.
Defective fusing unit Replace the fusing unit.
4.3.15 IMAGE SKEW
Symptom Possible cause Necessary actions
Incorrect installation of
paper Install the paper correctly.
Incorrect paper guide position
Adjust the paper guide correctly.
Defective registration roller Repair the paper feed unit.
Incorrect action of transfer
roller Check the transfer roller.
Defective engine board (EGB)
Replace the engine board (EGB).
Unclean separation pad Clean the separation pad.
Images are skewed
Defective spring Replace the spring for the friction pad.
4.3.16 BACKGROUND STAIN
Symptom Possible cause Necessary actions
Unclean transfer roller Clean the transfer roller.
Unclean paper path Clean the paper path.
Unclean registration roller Clean the registration roller.
Unclean fusing unit exit Clean the fusing unit exit.
The reverse side of the paper is not clean.
Defective fusing unit Replace the fusing unit.
4.3.17 NO PRINTING ON PAPER EDGE
Symptom Possible cause Necessary actions
Defective PCU Replace the PCU.
Defective toner cartridge Replace the toner cartridge.
Defective transfer belt unit Replace the transfer belt unit.
Images are not printed in the areas around the paper edges.
Transfer belt not contacting
PCU Check the transfer unit.
Troubleshooting Guide
SM 4-53 G190 Trouble- shooting
4.3.18 IMAGE NOT CENTERED WHEN IT SHOULD BE
Symptom Possible cause Necessary actions
Incorrect installation of
paper Install the paper correctly.
Incorrect paper guide position
Adjust the paper guide correctly.
Incorrect margin setting Adjust the margin setting.
Images do not come to the center.
Defective engine control board
Replace the engine control board.