Als Technical Description And Troubleshooting; Ambient Light Sensor; Als Troubleshooting - Nokia RM-333 Service Manual

ALS Technical Description and Troubleshooting

Ambient Light Sensor

Ambient Light Sensor
Ambient Light Sensor consists of the following components:
• Light guide
• Ambient Light Sensor (ALS)
ALS is a digital I2C interface component, having two channels with different spectral sensitivities. When
combined, the component responds to illuminance similar as human eye.
• Vdd Filtering capacitor C1103
Ambient Light Sensor information is used to control keypad and display brightness of the phone.
Keyboard backlight is turned OFF, when it's not needed. Display brightness is dimmed, when environment
lighting is dark.
Ambient Light Sensor is calibrated in production and can be re-tuned in service points though not
recommended unless calibration coefficient are lost for some reason

ALS troubleshooting

Context
Functionality check:
Steps
1. Connect phone to Phoenix and set the phone (e.g. on the table) so that the amount of ambient light seen
by ALS is as stable as possible.
2. Start Phoenix
3. Choose File -> Scan product
4. Choose Testing -> Display Test
5. Open the Lights tab, check Ambient Light Sensor check box, click Read, cover the sensor and click Read
again. When covered, Luminance reading should be less than after clicking Read without covering the
sensor.
Page 3 –46
Figure 18 Ambient Light Sensor
COMPANY CONFIDENTIAL
Copyright © 2008 Nokia. All rights reserved.
RM-333; RM-334; RM-335
BB Troubleshooting
Issue 2