Samsung MSYS 5150 Service Manual page 48

Circuit Description
5-7 H.V.P.S. (High Voltage Power Supply)
5-7-1 Output Specifications
Item
Supply Voltage
Bias Voltage
THV(Transfer High Voltage) (-)
THV(Transfer High Voltage) (+)
MHV(Main High Voltage)
5-7-2 Transfer High Voltage(THV)
THV output is a series circuit of positive and negative voltage generation part. Negative output is for cleaning
the OPC Drum and positive output is for drawing the
DC Converter that is composed of a PWM Contro l C i rcuit, a Blocking Oscillator and 4 times voltage rectifying
c i rcuit. the "THV-EA" goes to "low" positive and negative parts operate. And this state, THV positive output is
controlled by "THV-PWM" duty cycle, when it goes to "High", positive part outputs 0V, and negative part only
output -1000V. When some duty cycle is applied to the PWM input of H.V. c i rcuit, THV terminal outputs
positive voltage.
5-7-3 Main and Bias High Voltage(MHV,SUPPLY,DEV)
MHV generation part is composed of blocking oscillator and double voltage re c t i f y i n g c i rcuit. When "MHV-
EA" signal goes to "High", the MHV outputs, and this state, when "SUPPLY-EA" or "DEV-EA" input goes to
"Low", SUPPLY or DEV terminal corresponding it outputs the voltage that is generated by dropping MHV.
DEV output voltage is selectable 300V or 350V.
5-32
Printing/Initial
-500V
-300V
-1KV
-1.4KV
Toner on the paper. High voltage is generated by DC-
DCU On
-500V
-300V
-1KV
-1.4KV
Samsung Electronics