JVC 250 Service Manual page 81

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:
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)
Figure 5-16 Red image needs vertical adjustment (decrease).
5-26
The green image is the reference to which the red image and blue
Red - R137
Green - R148
Blue - R160
Model 250 Service Manual