Audio; Audio Troubleshooting - Nokia 6275 Baseband Description And Troubleshooting

6275/6275i (RM-154)
Baseband Description and Troubleshooting
• If the keypad malfunctions, check the switch soldering and the B2B connection.
If okay, check the keypad ASIP and the D2800.
• If the standby LED does not work, check the connection of the B2B connector
and above the circuit.
The baseband supports three microphone inputs and two earpiece outputs. The
microphone inputs are:
• MIC1 - used for the mobile terminal's internal microphone
• MIC2 - used for headsets connected to the Pop-port connector
• MIC3 - used for the Universal Headset
Each microphone input can have either a differential or single-ended AC connection to
the UEMEK circuit. The internal microphone (MIC1) and external microphone (MIC2) for
are both differential for Pop-port accessory detection. However, the Universal Headset
interface is single ended. The microphone signals from different sources are connected to
separate inputs at UEMEK. Inputs for the microphone signals are differential types. Also,
MICB1 is used for MIC1, and VFLASH1 is used for MIC2 and MIC3 (Universal Headset).

Audio Troubleshooting

Use the following to troubleshoot the audio:
• Perform a visual inspection of all the ASIPs and the UEMEK.
• Inject a 1KHz signal into MiC1 and trace it to the earpiece. The signal is amplified
by a factor of x8 only when you use an IHF signal.
Not installed Audio ASIPs
DC block capacitors
Audio ASIPs Audio ASIPs
• Ensure that the audio amplifier and the solder are okay.
• Check the IHF Speaker contacts.
• Check that the output is amplified by 8X. If not, ensure that the gain resistor
network is correct.
Page 30
Figure 36: Audio troubleshooting - UEMK side
Company Confidential
Nokia Customer Care
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Issue 1 - September 2006