Panasonic KX-FLM652CX Service Manual page 197

KX-FLM652CX
7.14.2. CHG-BIAS (Charge BIAS)/DEV(-) BIAS (Developing(-) BIAS)/DEV(+) BIAS
(Developing(+) BIAS) UNIT
When the CHG REM terminal becomes "L", the transistor Q21 turns ON by IC1, Charge BIAS(-1000V) is output from CHG
OUTPUT, Developing(-) BIAS(-200V) is output from DEV(-) BIAS. After that, when DEV CHG terminal becomes "L", Q71 turns ON,
and Developing(+) BIAS(+150V) is output from DEV(+) BIAS.
7.14.3. TRA(+) BIAS (Transfer(+) BIAS)/TRA(-) BIAS (Transfer(-) BIAS) UNIT
When the CHG REM terminal is "L" and the TRA CLK terminal is "Open", Transfer(-) BIAS(-1000V) is output from TRA OUTPUT
the moment Charge BIAS(-1000V) is output from CHG OUTPUT. When 8KHz PWM (pulse-width modulation) signal is input to the
TRA CLK terminal, Q1 turns ON by IC1, and TRA(+) CURRENT BIAS according to the PWM signal is output from TRA OUTPUT.
The PWM signal will be turned to a constant voltage by the resistor and the condenser, and input to the IC1. The IC1 compares
this voltage with the feedback voltage from T101 and controls the Q1. As for the transfer current, +25µA is output when DUTY of
the TRA CLK input signal is 0%, or +4µA is output when that is 72%.
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