Service manual
CB-22
CB CIRCUIT DESCRIPTIONS
Introduction
The CB chassis was developed to support CRTs ranging from 27 to 36. Major component of the deflec-
tion circuitry include IC2100, the vertical output IC; QX3203, the HOT (horizontal output transistor);
TX3205, the horizontal drive transformer; and on 32 and 36 sets IC3200, the E/W pincushion correction
amplifier. Of course the yoke, connected at 3Y3, and the flyback (or sweep) transformer, TX3204, are
major components as well.
Horizontal Drive
Horizontal drive (H-drive) enters the drive amplification circuitry through C3219 into the base of Q3201.
This transistor and Q3202 amplify the h-drive using the +15VSW for power. H-drive then passes through
the horizontal drive transformer for final wave shaping and voltage to current conversion. This modified
horizontal signal drives the HOT, QX3203. The HOT switches current flow in the primary winding of the
sweep transformer, TX3204. Regulated B+ is applied at pin 3. Horizontal output also drives the horizontal
scan signal in the yoke. Switching frequency of the HOT is 15.734 kHz.
1
3 4
5
6
TX3205
C3206
QX3203
LX3202
CX3212
C3204
Q3202
C3203
R3205
R3204
CX3205
RX3207
+15VSW
R3203
C3202
Q3201
C3201
R3202M
R3201M
C3219
CX3213
PROV
DX3202
CX3257
PROV
D3203
RX3212
CX3258
PROV
H-Drive from
Pin 19, IC2200
Flyback Line
H-Output to
Flyback & Yoke
<<Figure CB-20>>
Flyback Transformer
TX3204 uses HOT switching to generate high voltage. For this reason, the sweep transformer is often
referred to as the high-voltage (HV) transformer. HV should generally range between 29.4 and 31.2 kV.
The flyback does not, however, exclusively develop high voltage. A number of secondary voltages are
derived here as well. These should not be confused with the secondary voltages off the chopper, TX3401.
The voltages developed off TX3204 are referred to as tertiary voltages in the power supply circuit descrip-
tion.
Pin 2 of the sweep develops the +235V used to drive the cathodes at the CRT socket. This voltage is
rectified and smoothed to DC by DX3201 and CX3208 and then applied to pin 4 of the 2F5 connector.
Most of the secondary voltages are developed as DC in such a manner with the exception of pin 7s fila-