Sony TRIMASTER EL BVM-E171 Service Manual page 94

SUB power
The SUB power is used as power of each circuit of the G board.
SUB power output
• SUB5V power (Supplied as power of the secondary circuit of the G board)
• VCC voltage of SUB power IC (Output to the primary circuit of the G board)
• VCC voltage of PFC power IC/main power IC (Output to the primary circuit of the G board)
Power supply method
Insulated switching power unit
Components
• Switching power IC (IC6700)
• Transformer (T6700)
• Primary-side rectifier diode (D6703, D6704)
• Primary-side smoothing capacitor (C6703, C6705: Electrolytic capacitor)
• Secondary-side rectifier diode (D6705)
• Secondary-side smoothing capacitor (C6708: Electrolytic capacitor)
Setting output voltages
• SUB5V: 5 V
• VCC voltage of SUB power: 12 V
• VCC voltage of PFC power/main power: 17 V
Overcurrent protection
When an input overcurrent is detected at the DRAIN pin of the SUB power IC, switching operation is stopped. After
SUB power supply stops, the VCC voltage supplied to the PFC power and main power circuits stops and both power
circuits stops operating.
Description of circuit
The SUB power circuit uses an insulated switching power IC.
When the PFC voltage is input through the transformer to the DRAIN pin of the SUB power IC, a voltage is supplied
to the VCC pin through the internal circuit of the IC. When the voltage reaches 7.6 Vtyp, the voltage is monitored by
the feedback circuit (IC6701, PH6700) and is fed back to the SUB power IC to stabilize the power voltage. At the same
time, VCC voltages for the SUB power, PFC power, and main power circuits are output from the primary auxiliary
winding of the transformer to supply the VCC voltage to each power circuit.
POWER ON circuit
The VCC voltage is supplied from the SUB power circuit to the PFC power and main power circuits through the POWER
ON circuit.
The POWER ON circuit consists of the following components.
• Photo coupler (PH6103)
• Primary switch circuit (Q6110, Q6111)
• Secondary switch circuit (Q6114)
BVM-E171
7-2