Service manual

CB-21
Video Processing
D2205
R2224M
R2222M
R2223M
PROV
C2241M
C2214M
PROV
C2215M
PROV
Shutdown
DC Level
from QX3001
Flyback
Pulse
To Shutdown
Pin 18, IC2200
<<Figure CB-19>>
supplies an E/W pincushion correction signal to IC3200, an op-amp in the deflection circuitry. This signal is
calculated by IC2200 to correct horizontal deflection that would otherwise give a pincushion appearance
due to the geometry of the CRT. IC3200 and its function is further described in the deflection circuit
description. Note that it is only used in 32 and 36 CB receivers. Pincushion correction is wound into the
deflection yoke on the 27 receivers.
Two CB models, the IQB32B44W and the IQB36B44W, feature scan velocity modulation. Two coils
located under the purity magnets on the CRT accomplish scan velocity modulation. These coils are con-
trolled by the scan velocity modulator (SVM) board attached to the back of the CRT near the yoke. The
SVM receives fast-blanking and half-tone information from the microprocessor via the 4Q9 connector and
video information from pin 15 of IC2200 via the 4X9 connector. These signals are processed to generate a
current in the coils. The SVM varies this current to slow beam sweep at color transitions. The effect
produces a sharper video image in the CRT.