Horizontal Deflection Circuit Description And Schematic - Ceronix 1493 Service Manual

+12V Supply
Remote
Control
PCB
Horizontal
Position
20K
RC7
484 RC4
56pF
7.3VDC Hs
352
5.5Vpp 01,D6
Horizontal
Sync
The functions of the horizontal control circuits are:
1. To provide the horizontal output circuit
with a stable frequency with or without
incoming horizontal sync.
2. To be able to adjust the picture position,
horizontally, with respect to the raster.
3. To operate stability through periods of
missing horizontal sync pulses.
4. To keep the picture from drifting within
the operating temperature range.
All of these functions except for the picture
position adjustment are accomplished by the
phase locked loop. Delaying the horizontal
sync with an adjustable timer produces the
picture position adjustment.
The horizontal sync input circuit (pin 1) will
trigger the picture position one-shot (O/S) on
either the rising edge, or the falling edge, of the
horizontal sync pulse. To accomplish the edge
triggering, the sync pulse is differentiated by
capacitor into two short pulses, one for the
352 352
rising edge and one for the falling edge of the
sync pulse. Which edge is the trigger depends
on the bias voltage at pin 1. For positive edge
triggering, the bias voltage is set to 7.8 volts by
resistors and
I2 I3
I2 I3
triggering, the bias voltage is set to 4.1V by
connecting via the solder connection
I 12 I12
82
HORIZONTAL DEFLECTION CIRCUIT DESCRIPTION.
+24V to 27V Supply
5.4-6VDC
3.92K
11, E5
418
1N4007
Horizontal
333
SYNC INPUT
0Ω
1
2.7K
2 8
202 I4
7
12K
I2
1.8K
3
I1
22K
I3
17
GND
220uF
334
. For negative edge
.
IA
IA
3.92K
417
12 11
+
comp.
-
DELAYED
PICTURE
SYNC O/S
POSITION
O/S
2 3
7.3-8.7V Hs
7.3-8.7V
4Vpp 02,D6 4Vpp 03,D6
NEG.
Hs
IA
9
8.8K 25K
330pF
I12 351 I5 350
6,10
1,000pF-15KHz
0VDC
330pF-31KHz
56Vpp 62,D6
330pF-38KHz
The picture position O/S clamps timing capacitor
to 8.2 volts until horizontal sync triggers this O/S.
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The voltage on the timing capacitor drops at a rate set
by the horizontal position control
. When the voltage, at pin 2, drops below 4 volts
I 4 I4
the delayed sync O/S is triggered and capacitor
reset to its clamped voltage. The delayed sync O/S
functions the same as the picture position O/S with the
exception that it is not adjustable.
The flyback pulse, connected to pin 4 through
resistor , starts the negative slope of the saw
I6 I6
tooth generator. When the sawtooth wave, which is
produced by a current to capacitor
volts, the sawtooth generator switches back to the
positive slope part of the wave till the next FBP.
During the active part of the delayed sync pulse,
the multiplier gates current to capacitor
is dependent on the sawtooth voltage at the
delayed sync pulse time. Capacitor
"0" voltage for the multiplier which is the average
value of the sawtooth waveform.
If the delayed sync pulse occurs when the
sawtooth is at a low voltage part of its cycle,
capacitor discharges and the oscillator
346
346
frequency lowers. If the delayed sync pulse occurs
at the top part of the sawtooth wave no current
flows to capacitor
the horizontal oscillator to the incoming sync
pulses.
1N4007
2.2K.5W
+
341
100uF
2SC4159E
342
338
200Ω
2W
+24V
340
SAW TOOTH
TR . GENERATOR
4 5
Vs -.2VDC Hs 3-4VDC
1.5Vpp 04,E6 1.4Vpp 05,E6
11
6.8K
I13
45K
348
I6
1
GND
6,800pF-15KHz
Hs
I PRA
3,300pF-31KHz
416
3,300pF-38KHz
484 484
348 348
347
347
. This action, phase locks
346
346
12-18VDC Hs
33Vpp 27,E7
337
GND
MULTIPLIER
BIAS
6
Hs 2.4-3.4VDC
0Vpp 06,E6
+
1uF
10K
347
18
I7
1uF
+
344
and resistor
is
351 351
, drops to 3
which
346 346
sets the