Toshiba e-studio 202L, Service Manual, Page: 255 / 354

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June 2004 © TOSHIBA TEC e-STUDIO200L/202L/230/232/280/282 DRUM RELATED SECTION
11 - 5
11.3.2 Description of Operation
The function and operation of each signal is as follows.
ON/OFF signal (HVTM / HVTAC / HVTT / HVTGB / HVTSP):
ON/OFF signals are for each output of the main charger (needle electrode / grid), developer bias (AC),
transfer charger, transfer guide bias and separation charger. When these signals become “L” level, the
generation circuit of each bias on the high-voltage transformer turns ON to generate an output current/
voltage.
*
The negative DC component of the developer bias is turned ON/OFF by switching a reference volt-
age (HVDVR) separately. The positive DC component of the developer bias is output only when the
reference voltage (HVDVR) is under 0.6 V and also the developer bias (AC) ON/OFF signal
(HVTAC) is ON.
Reference voltage Vc (HVMVR / HVAVR / HVDVR / HVTVR / HVSAV):
The reference voltage is an analog voltage which is the reference of each output of the main charger
grid, developer bias (AC/DC), transfer charger and separation charger. Each output of the high-voltage
transformer can be linearly changed by switching these reference voltages.
The output operation of the reference voltage is as follows.
•
Outputs the adjustment values of the main charger, transfer charger, separation charger and devel-
oper bias in the NVRAM to ASIC.
• Outputs the reference voltage data from the ASIC to a D/A converter.
• Outputs the reference voltage Vc of each bias to the high-voltage transformer.
• The high-voltage transformer generates the output current/voltage which is proportional to the refer-
ence voltage.
* The reference voltage Vc is adjusted in the Adjustment Mode (05).
* The output values of the main charger (needle electrode) and transfer guide bias are fixed when the
high-voltage transformer is shipped from the factory.
Developer bias (AC) generation clock (HVCLK):
This clock signal is a reference of AC component of the developer bias.
High-voltage transformer leakage detection signal (HVSDWN):
This signal is for the abnormality (leakage) detection of the high-voltage transformer output. This signal
becomes “L” level at the occurrence of abnormality.