Toshiba e-STUDIO556 Service Manual page 746

Defective area
Developer bias output
Decreasing toner density
Image quality sensor/
Surface potential sensor
Main charger
Note:
1. Toner density correcting method
Change the setting value 'Toner density life correction setting (08-2816)' (6 is the default setting.)
0: Appox. 0.75% lower than the current value
1: Appox. 0.50% lower than the current value
2: Appox. 0.25% lower than the current value
3: The current value (Default setting)
4: Appox. 0.15% higher than the current value
5: Appox. 0.25% higher than the current value
6: Appox. 0.50% higher than the current value
7: Appox. 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.
e-STUDIO556/656/756/856(Ver03)
ERROR CODE AND TROUBLESHOOTING
Step Check items
9 Is the setting value proper?
Is the developer bias output normal?
10 Is the Auto-toner sensor connected
correctly?
11 Is the toner density low?
12 Are the image quality sensor and the
surface potential sensor normal?
13 Is the main charger dirty?
8 - 238
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.
Check the connection of the
connector of the Auto-toner sensor.
Correct the toner density.
(Note 2: See 'Toner density
correcting method'.)
Check the performance of the image
quality sensor and the surface
potential sensor. (See the trouble
shooting related with the image
quality control.)
Clean or replace it.
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