Toshiba e-STUDIO520 Service Handbook page 509

Defective area
Developer bias output
Decreasing toner density
Image quality sensor/ Sur-
face potential sensor
Main charger
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.
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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?
5 - 147
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.
Check the connection of the connec-
tor of the Auto-toner sensor.
Correct the toner density.
(Note 2: See 'Toner density correct-
ing method'.)
Check the performance of the image
quality sensor and the surface poten-
tial sensor. (See the trouble shooting
related with the image quality con-
trol.)
Clean or replace it.
e-STUDIO520/523/600/603/720/723/850/853
TROUBLESHOOTING
5