JVC 250 service manual Horizontal Vertical Deflection PCB - Main Functions

Chapter 5---Electronics

5.6Horizontal 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).

Model 250 Service Manual 5-21