User Guide

ALS troubleshooting

Context

• If a phototransistor is broken, replace it with a typical phototransistor.

• The phototransistor has to be also replaced, if calibration values are lost by some other reason.

• If the phototransistor is changed, the calibration value in the phone memory has to be changed to the

default value ‘1’.

• Make sure that you have completed Display and keypad backlight troubleshooting first before

starting ALS troubleshooting.

Here are some hints for ALS troubleshooting; the following troubleshooting diagram refers to these:

•

Phoenix

LED control tool also shows you luminance. The correct luminance in darkness is <20 lx, and in

office environment 100-2000 lx. The luminance value depends strongly on the light source and the angle

of the phone, so these values are only a rough guideline.

• LED driver control voltage measurement points can be found from the LED driver troubleshooting

section. When backlight brightness is set to 100%, both GENOUT signals are low, and enable PWM is 100%.

•

Phoenix

has an ambient light sensor calibration tool for changing calibration values. The pull-up resistor

calibration is done first. See the following procedure.

Steps

1. Cover the light guide (upper part of the A Cover).

2. Start

Phoenix

3. Choose File→Scan Product.

RM-49

Nokia Customer Care BB Troubleshooting and Manual Tuning Guide

Page 6 –44 COMPANY CONFIDENTIAL Issue 1