Horizontal Output Operation - Hitachi 36SDX88B Service Manual

9. Horizontal Output Operation
The Horizontal deflection circuit consists of Q701 (H.Driver), and Q702(H.output) to drive the H.DY. Q705 and
damper diode D705 switches according to the pulse voltage from the H.drive circuit to supply the H.DY coil with
a sawtooth current. C707, C708, C709, and C710 resonates with the H.DY coil. C718, C719, R718, and L707
corrects H.Linearity. The Horizontal output, Q705 and the damper 0705 perform switching operation to supply
the H.DY deflection current. When Q705 conducts, the current in the H DY coil increases linear until Q705 is cut-
off. The energy stored in the DY decreases, changing the resonance capacitors C707, C708, C709, and C710.
These capacitors then discharges across the DY coil in a reverse direction. D705 conducts to suppress this
reverse voltage. When the damper current becomes zero, C705 conducts again.
T702 secondary output voltages are rectified by D710 and D711 and provides DC bias for the H.DY through Q711
and Q712.
Figure below shows the components which are switched in TV/VGA mode and SVGA mode by switching Q708
and Q709.
In TV and VGA mode, Q709 is cut off, and Q708 is on. Q708 is made to conduct, adding C721 for 3" correction.
In SVGA mode, Q709 is on, and Q708 is off. Q708 is made to conduct, removing C721 for "S" correction.
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