NHL-4/4U
Troubleshooting Instructions
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Start
Is earpiece working?
Yes
Set phone in LOCAL mode. Use Phoenix audio test.
Continue
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Try to change earpiece.
No
Is it working now?
No
Set EXT IN, HP OUT, LOOP ON
Measure DC offset
voltage from earpiece
pads. Is it ~1.38V?
Yes
Measure MIC2B voltage
from XMICP (L102).
Is it ~2.2V?
Yes
Connect EXT audio signal (1kHz sine,
200mVpp) in XMICP and GND in XMICN.
Measure sine signal from
earpiece pads.
Is it~880mVp-p?
Yes
Change UPP and retest
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CCS Technical Documentation
Yes
Check L150, C155, R151, R152 and
No
lines. If OK, change UEM.
Check L102, C116, R150, C159, R153,
No
C150 and line. If OK, change UEM.
Measure sine signal
No
from R155 (UEM).
Is it ~130mVp-p?
No
Retest earpiece
Change
Yes
UEM
Check C154, R155,
C156, R154 and lines.
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