Ceronix 1493 Service Manual page 65

Thermal Protection
Vert.
Out
Boost
GND
11 12 13
1N4005 0Ω
395
382
1.5-2.7V Vs
4.7Ω
24Vpp 24,E4
396
.1uF
397
GND
22K
370
4.5-5.3V Vs
15.8K
5Vpp 16,E5
408
16 15 14
GND
LA7851
V. Ref.
In similar manner, the positive half of the
vertical current waveform is conducted by
transistor diode
373 373
and . Both transistors
404 404
be connected to pin 4 via solder connection H or
they may be connected to inverting transistor
and resistors
409 409
The inverting transistor is connected with
solder connection I and decreases the vertical
size at the top and bottom of the screen.
The ramp capacitor
differential amplifier at pin 6 and the negative
feedback from the yoke return line is connected
to pin 7. This negative feedback, which senses
the DC component of the vertical output voltage,
is also the current feedback for the LA7838. It is
made up of voltage divider resistors
+ and a wave shaping integrator.
390 390 393 393
The wave shaping integrator, capacitor
resistor , is used as the primary vertical
392 392
linearity adjustment.
VERTICAL DEFLECTION SCHEMATIC.
Vertical Linearity Circuit
V.+12V
DECREASES
200K
TOP AND
BOTTOM
VERT. SIZE. 412
I
D5
200K
371
PN2222
411
See
1N4148
Table
407
406
, and resistors
405 405
and
373 411
373 411
and .
412 412 413 413
I
is connected to a
401 401
388
388
200K
MPS2907
413
409
D5
H
200K
372
INCREASES
TOP AND
PN2222
BOTTOM
VERT. SIZE.
373
V
See
1N4148
0 TO 7 VDC
Table
405 404
390Ω, 2W
1,000uF
421
35V
+
449
The output of the vertical drive, differential
amplifier, is connected to the power amplifier
which drives the yoke. A booster circuit is
connected to the the power amplifier supply via
capacitor
when the booster is active, during vertical
retrace, the power supply to the vertical output
amplifier is doubled. Resistor
and capacitor
396 396
frequency vertical output stabilization circuit.
The vertical output at pin 12 is connected to
the vertical yoke. Resistor
across the yoke which stabilizes the vertical
deflection feedback loop. The yoke return is
372 372
decoupled by capacitor
may
current is sensed by resistor
H
raster position is adjusted by injecting current in
the vertical yoke return.
by transistor
and the V. RAS. POS. control
A capacitive multiplier circuit is connected in
series with the 27 volt line, in the 27" monitor, to
reduce the ripple voltage due to beam current
variations. Transistor
from the 27 volt line to the LA7838 deflection
supply input pin 8. Capacitor
and
196
196
connected to the base of this transistor. Diode
and
conducts the inductive current from the
199 199
vertical yoke during the first part of retrace.
and
391 391
A jumper at
multiplier circuit in the chassis with smaller
CRTs.
196
Capacitor multiplier for the 2793.
2SC4159E
197
1N4005
.1uF
399
199
GND
2SC3467
RAS. POS.
100Ω
420
1/2W
YC1
394
426
12-16VDC Vs
50Vpp 28,F6
YC2
427
and clamp diode
380
380
make up a high
397 397
421
421
and the vertical
449 449
385 385
This is accomplished
, with emitter resistor
420
420
conducts current
197 197
form a low pass filter which is
198
198
replaces the capacitive
196 196
22-28V Vs
.8Vpp 24,F7
270Ω
196
30Ω
198
+
1,000uF
119
VERTICAL
YOKE
such that
382
382
is a load resistor
. The vertical
,
394
394
.
483 483
and resistors
119 119
81