JVC 340 SC - Manual (Page 46)

Chapter 2—Functional Descriptions
2-34 Model 330. 340SC, and 370SC Service Manual
Figure 2-13 Vertical Deflection Board
Vertical Preamps
The vertical preamps (B, G, and R) each generate a ramp signal with the frequency
determined by the incoming signal VERTDR from the Horizontal Deflection Board. The
ramps generated in the preamp section have their common amplitude set by the
commanded height and are corrected for vertical linearity (linearity is individually
adjustable by R211, R311, and R411 and raster height is individually adjusted by R228,
R328, and R428). The common raster height is adjusted by a signal sent from the SCB to
the VDB via the serial bus. To control height, the operator presses the SIZE button on the
remote control, then adjusts height with the up and down arrow keys. The ramp
generated
by the red preamp is used elsewhere in the VDB for the generation of correction signals.