JVC 250 service manual Tighten spider lock down bolt

Chapter 4---Optical

CAUTION! Fan disconnection is acceptable for a short period of time only (preferably <20 minutes--maximum 45 minutes).

WARNING!!! Dangerous levels of ultraviolet and infrared radiation, dangerous glare, very high temperatures (180°C to 300°C) and high internal gas pressure are present at the Xenon Arc Lamp. Protect eyes from ultra violet light and infrared light by using X5 (375 to 700 nanometers), ANSI approved, shade goggles when actually working on the projector near the arc lamp source.

6.Access the "Shutters on Hide" box again from the System-Preferences menu and uncheck the box, then use the RGB and HIDE keys to hide

Green. This mutes video from the Green CRT but leaves the Green shutter open to allow Arc Lamp light from the Green ILA® to display on the screen.

7.Select ILA® Bias from the System-Factory Adjustments menu. Record the current ILA® bias level. Return to this bias level when this adjustment is complete. Record only the Green ILA® bias value because Red and Blue will return to their original levels when Green is reset.

8.Use the up-arrow key and adjust the ILA® bias for Green for maximum light output.

9.Adjust the Arc Lamp alignment screws (see Figure 4-2) to center the "hot spot" (brightest area). Figure 4-1 illustrates a "hot spot" on the screen.

NOTE: It is easier to perform the following procedure with one person standing in front of the screen holding a light meter and another person making the adjustments to the Arc Lamp.

10.Use the light meter to locate the brightest area or “hot spot”, (see Figure 4-1). Move the light meter around the screen to determine where the hot spot is located. The “hot spot” will be where the light reading is highest.

11.Adjust screw 1, 2, or 3, (see Figure 4-2) to move the hot spot to the center of the screen. Moving the “hot spot” will generally require adjusting two or more screws. Adjusting all three screws adjusts the Arc Lamp on the z- axis. Adjusting the three screws clockwise increases light output and rolloff.

12.Check for maximum brightness and readjust the z-axis as necessary after setting the x-axis and again after setting the y-axis.

13.Tighten spider lock down bolt.

Model 250 Service Manual 4-3