Nokia NHM-4 Series Assembly, Disassembly And Troubleshooting Instructions page 50

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Earpiece troubleshooting
Earpiece
Connect EXT audio signal 1kHz
(sine) (¨200mVp–p) in XMICP pads (C105)
and Ground in XMICN (C103)
Measure
sine signal
from earpiece pads.
Is it ~880mVp–p ?
Yes
Retest
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No
from UEM (R156)
Is it ~130mVp–p ?
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Measure
sine signal
Yes
No
Change UEM.
Check R156, C153,
C155, R166, R167,
C163, R161 and
line.
Page 27
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