Chapter 3: 2-1
6881091C63-A
Section 2
TROUBLESHOOTING CHARTS
1.0 Troubleshooting Flow Chart for Controller 
Power Up 
Alert Tone
 OK?
Speaker & 
Control 
head OK?
U0101
EXTAL= 
7.3728 MHz/ 
14.7456 
MHz? 
BUS+
activity when 
volume knob 
rotated?
MCU is OK
Not able to 
program 
RF Board ICs
Before replacing 
MCU, check SPI 
clock, SPI data, 
and RF IC select 
Replace 
Speaker / 
Control Head
U0221 Pin 34 = 
16.8 MHz?
Check 
FGU
Reprogram the 
correct data. & 
Check ASFIC 
and MCU
Check Control 
head and MCU 
(U0101, U0121, 
U0122, U0111)
Press PTT. No 
RF Output 
Power.
Red LED 
lights up?
Check 
Control 
head
Check 
FGU & 
Transmitter
Audio
at Pin 41
 
U0221?
Enable External PTT 
with CPS
External PTT 
enabled with 
CPS?
Radio could 
not PTT 
externally
DC
at assigned 
Acc. Con. 
Pin DC 
changes?
Check Components 
between U0221 and 
U0271
Check 
Connection 
to µP port
PTT
NO
YES
NO
YES
YES
YES
YES
NO
NO
YES
NO
YES
NO
YES
NO
YES
EXT
PTT
RX
AUDIO
Check 
Accessories
J0501
Audio at Pin 
16 & 
Pin 1
Check Spk. Flex 
Connection & 
Control head
Audio 
at Audio PA 
(U0271) 
input
Check 
ASFIC 
U0221
Check
 Audio PA 
(U0271)
Check 
Receiver &
 IF IC
Audio at 
Pin 2 
U0221?
NO
NO
NO
YES
YES
NO
YES
NO
Before troubleshooting the controller section 
according to this chart please check the follow-
ing:
1. Check tuning and CPS settings
2. Check if Alert Tones are enabled
3. Check if Control Head is OK
4. Check board visually
9.3V
DC at Pin 5 
of U0641? 
YES
NO
5V DC at 
Pin OUT of 
U0651? 
YES
NO
Check U0641, Q0641, 
Q0661, D0660 & 
D0661
Check U0651, D0651, 
D0621
Controller
Check