JVC 250 service manual

Chapter 7---Troubleshooting

The Horizontal Vertical Deflection PCB outputs H_OUT_FLYBACK to the Scan Reversal PCB. This is the horizontal deflection waveform that drives the horizontal CRT deflection yokes. The H_RED+, GRN+, and BLU+ are the horizontal deflection returns. The outputs of the vertical amplifier are V_RED+, GRN+, and BLU+. The returns are V_RED-, GRN-, and BLU-.

The Convergence Deflection PCB receives a sample of the vertical frequency from the Raster Timing Generator PCB (V_DRIVE) signal and generates a sawtooth waveform ( V_RAMP). It sends this signal to the Vertical Amplifier on the Horizontal Vertical Deflection PCB. It also sends geometric correction to modulate the vertical deflection waveform (V_PARAB) to the Horizontal Vertical Deflection PCB. The Convergence Deflection PCB sends convergence correction data received from the System Controller PCB to the Scan Reversal PCB (X_RED+, GRN+, and BLU+) and (Y_RED+, GRN+, and BLU+). The convergence correction data goes from the Scan Reversal PCB to the Convergence Yokes on each CRTs.

The Scan Reversal PCB sends the horizontal and vertical deflection waveforms to the appropriate CRT. It also converts the waveform for floor/ceiling and front/rear projector installations.

7-16 Model 250 Service Manual