Service manual

3-36 900 MHz Troubleshooting Charts
7.5V at
Pin 3/5 U202?
4/3.3V at Pin 1
U203.
5V at U202?
3.3V at U203?
MCU Check.
Power Up
Alert Tone
OK?
Speaker
OK?
U409 EXTAL=
7.3728 MHz?
U201 Pin 19
16.8 MHz.
U409 Reset
Pin 94 High?
MCU is OK.
Notabletopro-
gram RF Board
ICs.
Before replacing MCU,
check SPI clock, SPI
data, and RF IC
select.
Replace Speaker.
Read Radio OK?
Check
Setup.
Reprogram the
correct data.
See FGU
Troubleshooting.
Check Q400.
Replace
U202/U203.
Check any short to
SWB+,
Vdda or Vddd.
YES
NO
NO
YES
YES
NO
NO
YES
NO
YES
NO
YES
YES
NO
NO
YES
Troubleshooting Flow Chart for Controller (Sheet 2 of 2
)