Motorola M3000 - Handset Identification and Controls

Amplitude "A" - Represents adjusting FOCUS control,
R70, for best CRT center FOCUS.
Amplitude "B" - Represents adjusting FOCUS control,
R70, for best CRT edge FOCUS.
Amplitude "C" - Represents adjusting DYNAMIC FOCUS
coil, L52, for final p.p setting that is equal to difference be·
tween amplitude "A" and "B".
NOTE: After amplitude "C" is adjusted, amplitude "A"
must be reset to the original voltage value that provided
best CRT center FOCUS.
SIGNAL ..____,
GROUND - fflT
VIDEO~------------------~
INPUT
HORIZ.
SYNC IN
115/230 {
VOLTS AC
INPUT
VERT.
SYNC IN
STEPSCAN
INPUT
REGULATED
POWER
SUPPLY
STEPSCAN
AMPL.
HORIZ.
SYNC
AMPL.
+70V
HORIZ.
AFC/OSC.
VERT.
SYNC
AMPL./
SHAPER
,.___ ___ OSCILLOSCOPE ___ _
LEFT
EDGE
I
POS. PEAK
I
GRATICULE
I
NEG. PEAK
RIGHT
EDGE
I
POS. PEAK
\
- -1-r
DC OV REF-
l "B"
.1.- 1
1 - - -
VIDEO
AMPL/
OUTPUT
T = 63.5 uSec.
AEPC-00175
Figure 1. Adjusting Dynamic Focus with an
Oscilloscope
HORIZ.
PULSE
SHAPER/
DRIVER
VERT.
OSC./
DRIVER
DYNAMIC
FOCUS
HORIZ.
OUTPUT
VERT.
OUTPUT
r - - - - ..,
,m 31
L - - - -1
YOKE
CRT
HIGH
VOLTAGE
AEPC-00160-A
Block Diagram
THEORY OF OPERATION
POWER SUPPLY
(Refer to Figure 2.)
The power supply is a transformer operated, full wave,
regulated series pass circuit that maintains a constant out-
put voltage with line input variations of ± 12.5%. Depend·
ing on how connector S2 is wired, operation from 115 or
230 volts, 50/60 Hz is possible. Integrated circuit IC150 is
the reference amplifier, transistor 0152 is a regulator
buffer, transistor 0151 is the regulated output driver, and
0150 is the series pass transistor.
The output voltage, + 70V, appears at the emitter of 0150.
This voltage is divided between R157, R158 and R159.
The voltage appearing on the arm of potentiometer R 158
(70V ADJ. control) is the reference input to the non·
inverting input of reference amplifier I C150.
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