Toshiba E-STUDIO520, Service Manual, Page: 449 / 592

March 2005 © TOSHIBA TEC e-STUDIO520/600/720/850 TROUBLESHOOTING
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5.1.16 Troubleshooting for surface potential control
[Corrective action when " Service Recommended for SPC" is blinked]
Check the control status of the surface potential sensor (05-242).
<When "2" is displayed: sensor error>
The sensor detection value is abnormal or the sensor output value is not changed even
though the main charger bias value is changed.
Is the connector of the surface potential sensor connected properly?
Is the main charger attached poorly?
Are leaks and such occurring?
l
!
YES
"
After removing, if any, dust and correcting the defect, perform the "sur-
face potential sensor control check" (described later).
NO
Is the connector of LGC board CN337, CN342 or that of SYS board CN103 disconnected?
l
!
YES
"
Connect them properly again, and perform drum surface potential sen-
sor control / condition check (described later).
NO
Is the main charger wrongly installed?
Are the main charger grid/wire wrongly installed?
Is the charger leakage, etc. occurring?
l
l
!
YES
"
Remove the dusts or toner stains if any, and then install them properly.
Perform the drum surface potential sensor control / condition check
(described later)
NO
Check the value for 05-244. Is the value for 05-244 within the range between 400 and 800?
l
l
l
l
l
l
l
l
l
l
l
l
!
NO
"
1) Perform the charging transformer output (05-210) and check that the
value is within the range of -500±12V. If the voltage is outside the
range, replace the HVT board and perform the drum surface poten-
tial sensor control / condition check (described later).
2) When the charging transformer output is within the range of -
500±12V, replace the drum surface potential sensor, and perform the
drum surface potential sensor control / condition check (described
later).
3) If the problem still occurs, replace the LGC board, and perform the
drum surface potential sensor control/condition check (described
later).
YES