Hughes JVC 200, Service Manual

Page: 81 / 140

Chapter 3 Service Adjustments
3. Use the right/left arrow keys on the remote control and adjust
the Flat Field to 0%.
4. From the System menu, select Maintenance, then select #3,
ILA® Bias. Record the ILA
®
Bias current value (the Green bias
will be readable). This bias value will be returned to when this
procedure is complete. The Green value only need be recorded
because Red and Blue returns to their original values when
Green is reset.
5. Use the right arrow key to increase the ILA
®
Bias so the Flat
Field turns white. If the screen begins to turn from white to a
yellow-tinge, use the left arrow and adjust the bias back until an
all white flat field is observed. The flat field screen must be
white to properly perform the arc lamp focus and alignment.
6. Loosen the large flathead screw (½ turn CCW) at the bottom of
the Arc Lamp cover (Figure 4-2), and lift the cover.
7. Defocus the Arc Lamp by turning the Focus Adjust Screw ( see
Figure 3-1 ) until a bright, circular area ( see Figure 3-2 ) is
achieved. This is the Arc Lamp’s “hot spot.” The sides, top, and
bottom areas will taper off in brightness. When performing
defocus, do not attempt to narrow the circle too much-try to
obtain a uniform circular area.
Figure 3-1. Arc Lamp Focus adjustments.
8. Loosen the 4 X-axis (horizontal) alignment screws (indicated by
the letter H inside the screw heads in Figure 3-1).
3-2 Model 200 Service Manual