JVC 340 SC, 330, 370 SC service manual ILA Bias Settings, Note On Super Contrast Ila Assemblies

Chapter 3---Service Adjustments

8.After Yoke rotation, readjust Geometry, Convergence and CRT Mechanical focus.

3.6ILA® Bias Settings

The ILA® Bias settings are factory set and should not normally need adjustment unless specific maintenance has been performed that requires an ILA® Bias readjustment. Avoid readjusting the ILA® Bias settings unless absolutely necessary.

The ILA® Bias settings adjust the electrical bias levels to each ILA® assembly to a "just off" threshold point so that even the smallest incoming light from the CRT makes the ILA® assembly react. When properly set, this adjustment will put each ILA® assembly at the threshold of operation. If not properly set, image black level will be adversely affected and the ILA® assembly won't react properly to incoming light. ILA® Bias adjustments should be done in a darkened room.

NOTE: If the room cannot be darkened enough to set the ILA® Biases using the screen, try holding a piece of paper a few inches from the lens of the color you are adjusting. Adjust the bias in the usual manner while viewing the entire ILA® assembly area on the paper.

Note On Super Contrast Ila® Assemblies

If using optional Super Contrast ILA® assemblies, the High Contrast Compensator may have to be adjusted for each color prior to performing the ILA® bias adjustment. This procedure is required whenever an ILA® assembly is replaced or if the compensator adjustment lever is inadvertently moved.

To set the High Contrast Compensator:

1.Press the HIDE key to mute CRT images.

2.Block the light from the green and blue lenses with the lens caps.

3.Move the front cover forward to provide access to the ILA® assemblies.

4.Disconnect the connector from the top of the red ILA® assembly.

5.Move the Compensator lever (this lever is just in front of the ILA® connector) to the right and left until the darkest level appears on the screen. If a screen is not available use a piece of white paper in front of the lens.

6.Reconnect the connector to the red ILA® .

7.Repeat the above steps for the green ILA® and the blue ILA® . Block the light from the other two lenses each time.

8.Replace the cover.

9.Remove all lens caps

The CRTs will automatically cut off when you enter the ILA® Bias mode. Any light on the screen is being reflected by the ILA® assembly.

To set the ILA® Frequency and Bias levels:

3-8 Model 330, 340SC, 370SC Service Manual