JVC 250 - Manual (Page 76)

Chapter 5---Electronics
Model 250 Service Manual 5-21
5.6 Horizontal Vertical Deflection PCB
Horizontal Vertical Deflection PCB - Main Functions
! Drive the main horizontal deflection coils to provide horizontal raster scan
for the CRTs
! Drive main vertical coils to provide vertical raster scan for the CRTs
! Horizontal raster centering for all three colors
! Switch mode power supply generating the required proportional DC
supply
! Horizontal width adjustment
! Horizontal retrace switch network
! Left/right pincushion and keystone correction
! Vertical linearity adjustments individually for all three colors.
! Vertical raster centering for all three colors
! IIC interface.
Horizontal Vertical Deflection PCB - Inputs
H_BAND:0-3 - horizontal scan frequency bands, from Raster Timing Generator
PCB.
/H_ENABLE - from the Raster Timing Generator PCB, enables the horizontal
deflection supply. Low = enabled deflection, High = disabled deflection.
H_DRIVE - square wave from the Raster Timing Generator PCB, 50% duty cycle
synchronized to the selected horizontal sync.
H_F2V - a DC voltage from the Raster Timing Generator PCB, proportional to
horizontal frequency
H_LOCK (neg.) - Deflection Yoke Connector Interlock return from the Scan
Reversal PCB.
DEFL_OK - deflection status signal from the Scan Reversal PCB (high = good,
(about 2 V), low = no scan).
V_RAMP - vertical ramp waveform from the Convergence Deflection PCB,
(about 4 Vpp).
V_PARAB - vertical parabola waveform from the Convergence Deflection PCB,
(about 4 Vpp).
FRONT/REAR - front or rear projection status line from the Scan Reversal PCB.
(FRONT = low, REAR = high).
FLOOR/CEILING - floor or ceiling projection status line from the Scan Reversal
PCB. (FLOOR = low, CEILING = high).