Vertical Flyback Blanking Circuit; Blanking Operations: Signal Mode Changeover, Power On/Off And Unstable Sync Signals - NEC MultiSync FE001SB Service Manual

7.3 Vertical Flyback Blanking Circuit

The V-OUT output from the MPU U701 Pin 32 is synthesized with the vertical deflection output that has been
shaped by the circuit of C409, D402, R415, R414, and C408. The synthesized output is used for the blanking
operation of the vertical flyback period, by switching Q401 that is connected to G1.
U701
32pin
7.4 Blanking Operation: Signal Mode Changeover, Power ON/OFF and Unstate Sync signals
The image blanking operation at the time of signal mode changeover and power ON/OFF is carried out by
controlling the G1 voltage. This voltage control is actually effected by Q307 that makes the switching of the
blanking pulse output sent from the MUTE1 circuit of the U701 Pin 2 through D310.
When the sync signals become unstable, the blanking operation is carried out by controlling the G1 voltage,
whose operation is actually effected by Q307 that makes the switching of the blanking pulse output sent from
the HUNLOCK circuit of the U501 through D311.
G1
12V
U701
2pin
U501
17Pin
(Fig. 7.4) Blanking Operation: Signal Mode Changeover, Power ON/OFF and Unstable Sync signals
G1
(Fig. 7.3)Vertical Flyback Blanking Circuit
T301
5pin
7-18
vertical deflection output