Toshiba e-STUDIO163, Service Manual

Page: 164 / 236

e-STUDIO163/203 © 2005 - 2008 TOSHIBA TEC CORPORATION All rights reserved
DRUM RELATED SECTION
11 - 6
11.4.2 Description of Operation
The function and operation of each signal are as follows:
ON/OFF signals (HVTM-0, HVTAC-0, HVTT-0, HVTSP-0, HVTGB-0):
These are for the charge grid (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 switching regulator is turned ON to generate an output current/voltage.
* The negative DC component of the developer bias is turned ON/OFF by switching the reference
voltage (HVDTR-0) separately. The positive DC component of the developer bias is output only
when the reference voltage (HVDTR-0) is 0.6 V or less and also the developer bias ON/OFF signal
(HVTAC-0) is ON.
Reference voltages Vc (HVMVR-1, HVDTR-1, HVTVR-1, HVSAV-1):
These are analog voltages which are the reference of each output of the charge grid, developer bias,
transfer charger and separation charger. Each bias output can be linearly changed by switching these
reference voltages.
The output operation of the reference voltage is as follows:
1) The adjustment values of the main charger, developer, transfer and separation bias in the Flash
ROM are output to the SoC.
2) The reference voltage data are output from the SoC to D/A converter.
3) Converted to analog data by the D/A converter
4) The reference voltage Vc of each bias is output to the high-voltage generation circuit.
5) The high-voltage generation circuit generates the output current/voltage which is proportional to
the reference voltage.
* The reference voltage is adjusted in the Adjustment Mode (05).
* The output values of the main charger and transfer guide bias are fixed when the high-voltage trans-
former is shipped from the factory.
Developer bias (AC) generation clock (HVCLK-0):
This clock signal is a reference of the AC component of the developer bias.
High-voltage generation circuit leakage detection signal (HVSDWN-0):
This signal is for leakage detection of the high-voltage generation circuit. This signal becomes "L" level
at the occurrence of such an abnormality.