September 9, 2011 68009482001
7-34 Troubleshooting Charts and Error Codes Troubleshooting Charts
Figure 7-32. APCO TX Audio - B
Parts placed properly
Is ~1.35Vdc
present at U1801-10 &
~3.3Vdc present at
U1801-4?
There may be an issue with the
internal board routing of
VCC_1.35V and/or VCC_3.3V.
Is there a 1kHz,
~145mVrms tone at
R1811?
Replace U1801.
Verify AUX_TX (J104-
17) is being routed
properly through the low
speed board & flex
cable to C1806.
Verify R1806 & C1806
are placed properly &
the R1806 resistor
value is 560 Ohms.
No
No No
Yes
Yes
Yes
Is there continuity
between J104-17 on the
low speed board & C1806
on the Mainboard?
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