Samsung CC9511 Service Manual page 15

rest of the trace. Adjust this variable inductor so the
right and left sides of the picture are the same size.
3.11. HORIZONTAL
DC CENTERING
In the horizontal section of
a monitor the yoke has DC
on the cold end and a
flyback pulse on the hot side.
The current ramps in a
sawtooth fashion center
around zero. If a parallel
coil is added the current
through the yoke is not
effected.
With the addition of a
battery and limiting resistor
the DC current is added to
the current ramp. A plus
and minus supply gives full
control of the DC offset
current.
The batteries or power
sources are created off a
small secondary winding
turning the parallel coil into
a transformer. The final
circuit has no AC effect on
the yoke but can cause a
+ /-
current flow through the
yoke.
180uH YOKE
.iffffJiiii-
2 to 20MH COIL
RES. BAT.
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~
:cr+
3.12. FLYBACK TRANSFORMER
The flyback transformer is separate from the
horizontal section. This is done to allow greater
14
flexibility when changing frequency and tube size. A
small independent 'horizontal' section powers the
flyback transformer and creates the high voltage.
3.13. X-RAY SHUT DOWN
When a fault in the high voltage section is detected
the horizontal base drives are shut down. An over
current condition in the high volt supply or an
overvoltage condition will trip a TlA31(IC405)1
2N2907(Q413,Q414) latch. Turning off the power
resets the latch.
3.14. TUBE BIAS SUPPLIES
Focus and G2 supplies come from a bleeder located
in the flyback transformer.
3.15. FOCUS
The focus voltage is obtained form the flyback
transformer. There is no focus modulation used in
this color monitor.
3.16. MASTER BRIGHTNESS
The G2 voltage comes from the flyback transformer.
3.17. HIGH VOLTAGE REGULATOR
The patented high voltage regulator sits between the
supply and the top of the primary of the flyback
transformer. An onboard switching regulator is
powered from the 17 volt supply. The regulator
watches the second anode voltage through a 300-mega
Ohm resistor in the flyback transformer. During
flyback, the regulator pulls the top of the flyback
transformer negative while the flyback pulse is raising
the other end. In this way the size of the pulse, as
seen by the flyback transformer, is varied to keep the
second anode voltage constant independent of load.
The regulator should be adjusted by "high voltage
adjustment" to the desired high voltage.