This article describes the light meter and video adjustment tool setup for iMac (Summer 2000 and Slot Loading) video adjustments.

This article covers repair procedures for authorized service providers on selected Apple products, but we have published them in the Knowledge Base for the general public for educational purposes. At this time, there are a limited number of repairs that a customer can perform and these are covered under the customer installable parts program http://www.info.apple.com/installparts . If you have not been authorized to perform these procedures, please contact Apple (800-APL-CARE in the USA) or your local authorized service provider to schedule a repair.

DANGER! This procedure exposes you to high voltages that can result in death or serious injury. DO NOT ATTEMPT THIS PROCEDURE IF YOU HAVE NOT BEEN CERTIFIED AS AN APPLE-AUTHORIZED TECHNICIAN.

The R77 light meter is shown below in Figure 1.

Figure 1 R77 Light Meter

Products affected

• iMac (Slot-Loading)
• iMac (Summer 2000)

Tools Required

• Display Adjustment Utility
• jumper adjustment tool (922-4165)
• light meter Model R77 (076-0310)

Note : The adjustments were optimized for light meter Model R77. To obtain more consistent color results, use only the R77 light meter when performing color adjustments on the slot-load iMac.

Light Meter Setup

1. Before you begin, remove the 10X multiplier plate from the lens.
   
   
2. Display screen luminance typically ranges from 10 to 50 fc. Take readings on the R77 light meter from the bottom scale only. The scales on the light meter are shown Figure 2.
   
   
   Figure 2 R77 Light Meter Scales
   
   

To Measure Screen Luminance

1. Set the scale switch to the bottom position (to set up the 10-50 fc scale). Refer to Figure 3.
   
   
2. Place the lens against the middle of the screen and read the bottom scale. Note: When the light meter is not in use, slide the scale switch to its top position, and store the meter in its protective case.
   
   
   Figure 3 Bottom Scale on the Light Meter
   
   
3. If you suspect the light meter is giving false readings, verify the readings with a known-good light meter or photometer. Also check the age of the R77 light meter by its four-digit manufacturing date stamp (such as 0398 for March 1998). See Figure 4 below.
   
   
   Figure 4 Manufacturing Date Stamp
   
   

Jumper Adjustment Tool Setup

1. The jumper adjustment tool (922-4165) shown in Figure 5, must be installed to save cutoff and white balance adjustments to the factory space.
   
   
   Figure 5 Jumper Adjustment Tool
   
   
2. Warning : This product contains high voltage and a high-vacuum picture tube. Be extremely careful when working around a live CRT. Turn off the computer. Remove the bottom housing and the top rear housing to access the video board. See Figure 6.
   
   
   Figure 6 Video Board
   
   
3. Remove the left ground cable from the video board. See Figure 7.
   
   
   Figure 7 Ground Cables on the Video Board
   
   
4. Connect one end of the jumper adjustment tool (922-4165) to the video board pin. Connect the other end to one of the ground pins. See Figure 8.
   
   
   Figure 8 Connecting the Jumper on the Video Board
   
   
5. Turn on the iMac and proceed with the adjustments.
   
   

Related Articles

• article 95105: iMac: Focus Adjustment
• article 95106: iMac: Screen Voltage Adjustment
• article 95107: iMac: Cutoff Adjustment
• article 95108: iMac: White Balance Adjustment
• article 95109: iMac: Geometry Adjustment
• article 95110: iMac: S Correction Adjustment