JVC 250 service manual Horizontal Vertical Deflection PCB - Service Adjustments

Chapter 5---Electronics

the V_PARAB waveform. The output waveform V_RGB+ goes to the Scan Reversal PCB and then drives the Vertical Deflection Yokes. The Vertical Deflection Yoke return signal to the Horizontal Vertical Deflection PCB is V_RGB-.

Horizontal Vertical Deflection PCB - Service Adjustments

Vertical Size Adjustment

Tools Needed

Miniature Potentiometer-Trimmer Adjustment tool

To adjust the Vertical height (see Figure 5-15):

1.Remove the rear cover and pull the Interlock switch out to the Service Mode position.

2.Power ON the projector by IR Remote or PC, and allow it to stabilize for a minimum of 15 minutes

3.Use the X-hatch test pattern.

NOTE: The green image is the reference to which the red image and blue image will be matched. The green height pot should not need adjustment except when the green CRT has been replaced.

4.Hide Blue and view Red and Green.

5.If Red is higher than Green at the top and lower than Green at the bottom of the X-hatch image, or If lower than Green at the top and higher at the bottom, adjust Red vertical pot (R137) to correct the error.

Vertical Adjustment Potentiometers (see Figure 5-15) Red - R137

Green - R148 Blue - R160

Figure 5-16Red image needs vertical adjustment (decrease).

5-26 Model 250 Service Manual