I/O Expander Troubleshooting; Audio Troubleshooting; Audio Troubleshooting Test Instructions - Nokia RM-484 Service Manual

RM-484; RM-485; RM-486
BB Troubleshooting

I/O expander troubleshooting

Troubleshooting flow

Audio Troubleshooting

Audio troubleshooting test instructions

Single-ended external earpiece and differential internal earpiece outputs can be measured either with a
single-ended or a differential probe.
When measuring with a single-ended probe each output is measured against the ground.
Internal handsfree output is measured using a current probe, if a special low-pass filter designed for
measuring a digital amplifier is not available. Note also that when using a current probe, the input signal
frequency must be set to 2 kHz.
The input signal for each loop test can be either single-ended or differential. Exception to this is a digital
microphone, which needs input signal from an external sound source (laptop speaker) to playback eg. 1kHz
sine wave from 5cm distance
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