Audio Failure - Nokia NSW-5 Series Service Manual

NSW-5
Disassembly and Troubleshooting Instructions

5. Audio Failure

In this kind of fault, it is useful to check first that slide rails and the rail
connector are OK.
Uplink (microphone) and downlink (speaker) are disfunctional
Voltage at C271 is 2.8 V HEADSETINT
(without external audio devices)
If the downlink is broken, check that speaker is OK; ie. the grey metal
parts are not sticking out of the black plastic causing short circuits on the
speaker pads, or the membrane broken.
Uplink (microphone) is disfunctional
MICP voltage at pin 5 of V252 is 1.8 V
MICN voltage at pin 4 of V252
(J100) is 0.3 V during a call
Analog audio signal (a few millivolts)
at V252 pins 1 and 3 during a call
Digital PCM data at J253 during a call
Figure 4. Troubleshooting diagrams for Audio failure
Page 22
YES
Voltage at C278 is 2.8 V HOOKINT
(without external audio devices)
YES
YES
Frequency at J255 is 1 MHz
square wave 2.8 Vpp
YES
Frequency at J256 is 8 kHz
square wave pulses 2.8 Vpp
YES
YES
DC voltage at V252 pins 1 and 3
is 1.4 V during a call
YES
YES
E Nokia Mobile Phones Ltd.
PAMS Technical Documentation
NO
Check R260 and R270
NO
Check R268, R265 and R260
NO
Check N250 (Cobba)
NO
Check N250 (Cobba)
NO
Check slide and slide connector
OK
Check microphone and micbias
components V250, V252, R259,
C286 and R275
If OK, check that VR1_sw is 2.7 V
during a call (R259)
NO
Check
N250 (Cobba)
NO
Check C256, C285
and PWB routings
NO
Check
N250 (Cobba)
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