Toshiba e-STUDIO556 Service Manual page 240

Defective area
Main charger output
Developer unit
Developer bias output
Increasing toner density
Image quality sensor/
Surface potential sensor
Drum cleaning blade
Note:
1. Toner density correcting method
Change the setting value 'Toner density life correction setting (08-2816)' (6 is the default setting.)
0: Approx. 0.75% lower than the current value
1: Approx. 0.50% lower than the current value
2: Approx. 0.25% lower than the current value
3: The current value (Default setting)
4: Approx. 0.15% higher than the current value
5: Approx. 0.25% higher than the current value
6: Approx. 0.50% higher than the current value
7: Approx. 0.75% higher than the current value
<Caution for correction>
When increasing or decreasing the toner density too much, the image may become poor or the
life of developer material, cleaner, photoconductive drum and fuser unit, etc. may shorten.
Therefore it is not recommended to correct (to shift) the toner density basically. If it is shifted,
make sure that the image may be improper in a few minutes after shifting.
© 2011 - 2014 TOSHIBA TEC CORPORATION All rights reserved
Step Check items
9 Is the setting value proper?
Is the main charger output normal?
10 Is the contact between the drum and
developer material normal?
11 Is the setting value proper?
Is the developer bias output normal?
12 Is the Auto-toner sensor connected
correctly?
13 Is the toner density high?
14 Are the image quality sensor and the
surface potential sensor normal?
15 Is the drum cleaned properly?
8 - 239
Prescription
Replace the high-voltage transformer
with a new one and print out a test
chart.
If any abnormal image appears,
check the harness connection
between the LGC board and the
high-voltage transformer, power
supply and stain on the main charger
wire.
Replace the high-voltage transformer
with a new one and print out a test
chart.
If any abnormal image appears,
check the harness connection
between the LGC board and the
high-voltage transformer, power
supply and stain on the main charger
wire.
If the setting value is out of
specification, adjust it.
If the output is not normal, check the
circuits. (Note 1)
Check the connection of the
connector of the Auto-toner sensor.
Adjust the toner density.
(Note 2: See the toner density
correcting method.)
Check the performance of the image
quality sensor and the surface
potential sensor. (See the
troubleshooting related with the
image quality control.)
(See the troubleshooting for the poor
cleaning.)
e-STUDIO556/656/756/856/557/657/757/857
ERROR CODE AND TROUBLESHOOTING
8