JVC 340 SC, 330, 370 SC Model 340SC and 370SC Arc Lamp Alignment and Focus, Y-Axis Plate

Chapter 3---Service Adjustments

Model 340SC and 370SC Arc Lamp Alignment and Focus

To check Model 340SC and 370SC Arc Lamp alignment, observe the anode shadow on the blue dichroic mirror (the blue dichroic mirror is the first mirror after the condensing lens). Verify that the anode shadow (small, dark oval inside the light circle) is a uniform oval that is no more than ½ inch or no less than ¼ inch in diameter.

If the oval looks non-uniform or has a flare coming from one (1) side, adjust the X-Y plates in the following manner:

1.Use a standard Phillips screwdriver and loosen the two (2) top screws on the pivot holes (refer to Figure 3-9). Slide the plates on their pivots until the shadow looks uniform.

2.While viewing Test Pattern 6 (Static Flat Field) the uniformity on the screen should become more centered also.

To refocus the Model 340S and 370SC Arc Lamp:

1.Adjust the Z-axis of the Xenon Arc Lamp using a 9/64 inch hexhead balldriver and rotate the screwhead (see Figure 3-9) for overall brightness from the center to the edges with a minimum of roll-off (roll-off is the gradual difference in brightness from the center of the screen to the edges). Only a turn or two should be required.

2.Verify the proper brightness after the adjustments are complete with a light meter by measuring the foot-candles of light output at the screen center and multiplying this measurement by the area of the screen in square feet.

Example: If the screen area is 15x20 = 300 sq. ft.

and the light output on the light meter measures 20 foot-candles, the brightness level in lumens is 300x20 = 6000 lumens.

Y-Axis Plate

X-Axis Plate

Z-Axis Screwplate

3-20 Model 330, 340SC, 370SC Service Manual