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Ambient Light Sensor troubleshooting and re-calibration

Introduction to ALS troubleshooting and re-calibration

If the Ambient Light Sensor (ALS) functionality is inoperative, check the ambient light sensor (N6502) and

change it, if necessary. Also, check the capacitor C6504 (100n).

The ALS components are located at the top of the UI flex as illustrated in the figure below.

Figure 18 ALS components

ALS information is used to control the keypad and display brightness of the phone. The keyboard backlight

is turned OFF, when it’s not needed. Display brightness is dimmed, when environment lighting is dark. ALS

is calibrated in production and can be re-tuned in service points though not recommended unless calibration

coefficient is lost for some reason.

Note: ALS calibration is also required for Light SWAP Engines, because ALS is not factory calibrated

for Light SWAP.

When executing the ALS calibration, a reference phone that includes calibrated ALS is required. The ALS re-

tuning instructions show why the reference phone is needed.

Note: Make sure that you have completed the display and keyboard backlights troubleshooting

before starting the ALS troubleshooting.

There is an Ambient Light Sensor window in the Phoenix Display Test tool, which shows the luminance value.

The correct luminance in darkness is <20 lx, and in an office environment 100-2000 lx.

Note: The luminance value depends heavily on the light source and the angle of the phone against

the light source, so the values above can only be used as a rough guideline. Phoenix has an ambient

light sensor calibration tool for changing the calibration values.

RM-356

BB Troubleshooting and Manual Tuning Guide

Page 3 –38 COMPANY CONFIDENTIAL Issue 1

Nokia MOBILE TERMINAL User Manual

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