Toshiba e-STUDIO520 Service Handbook page 491

Defective area
Main charger output
Developer unit
Developer bias output
Increasing toner density
Image quality sensor/
Surface potential sensor
Drum cleaning blade
Note: Note:
1. Toner density correcting method
Change the setting value 'Toner density life correction setting (08-414)' (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. There-
fore 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.
© 2005 - 2007 TOSHIBA TEC CORPORATION All rights reserved
Step Check items
8 Is the setting value proper?
Is the main charger output normal?
9 Is the contact between the drum and
developer material normal?
10 Is the setting value proper?
Is the developer bias output normal?
11 Is the Auto-toner sensor connected
correctly?
12 Is the toner density high?
13 Are the image quality sensor and the
surface potential sensor normal?
14 Is the drum cleaned properly?
5 - 129
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 sup-
ply 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 sup-
ply and stain on the main charger
wire.
If the setting value is out of specifica-
tion, adjust it.
If the output is not normal, check the
circuits. (Note 1)
Check the connection of the connec-
tor of the Auto-toner sensor.
Adjust the toner density.
(Note 2: See the toner density cor-
recting method.)
Check the performance of the image
quality sensor and the surface poten-
tial sensor. (See the troubleshooting
related with the image quality con-
trol.)
(See the troubleshooting for the poor
cleaning.)
e-STUDIO520/523/600/603/720/723/850/853
TROUBLESHOOTING
5