JVC 250 service manual 30View of CRTs, Relay lenses and ILA Assemblies

Chapter 5---Electronics

CRT Electronic Focus

The Electronic Focus is factory-set and normally will not need to be adjusted except after component replacement, maintenance, or if wide temperature variations exist between the factory and the field location. View one color at a time.

Tools Needed

Medium Phillips-head screwdriver

To perform the Electronic Focus adjustment:

1.Remove the front and rear cover.

2.Power the projector ON and allow it to stabilize for at least 15 minutes.

3.Select the Focus pattern (test pattern #6).

4.Zoom the Projection Lens to the widest angle and adjust the Projection Lens focus for the sharpest image.

5.View Green. Hide Red and Blue.

6.Adjust the Green Electronic Focus located on the side of the High Voltage Power Supply (see Figure 3-5 and 3-6) for a sharp focus of the Focus pattern at the center of the screen.

7.Repeat the above steps for Red and Blue.

Figure 5-30View of CRTs, Relay lenses and ILA® Assemblies.

5-56 Model 250 Service Manual