Is power at 
C3161 
>-20dBm? 
Take continuity 
check of traces to 
U702.
1
At Rx, is L701 high and 
L702 low?
At Tx, is L701 low and 
L702 high?
Is power at U3001 input 
Tx: C3112
Rx: C3102
>-20dBm?
Check continuity at 
L701 and L702. 
Fault found?
Check parts around 
U3001. If OK, 
replace U3001. 
Replace suspected 
components.
Replace U702. 
Control voltage 
at R705
0.3<Vdc<10.6?
Is Vdc = 4.55V at pin 
3 of Q3123 during 
Rx and at Q3156 
during Tx?
For Tx: Check and visual inspect D3135 -
D3138, C3103, C3140, C3141, C3143, 
C3147, L3139, L3145.
For Rx: Check and visual inspect D3102 -
D3105, C3101, C3107, C3108, C3110, 
C3113, L3106, L3112.
Is Vdc at C742 5V, 
Vdc at C726, C734, 
C737 2.775V?
Is Vdc at Y701 
pin 4 2.775V?
16.8MHz at pin 
3 of Y701 and 
C736?
16.8MHz at 
L753?
10.8Vdc at pin2 
of D723?
2.775Vdc at pin 
4 of D722?
Check and visual 
inspect U746 circuitry. 
Fault found? 
Check 2.775V and 
5V supply.
Check 2.775V 
supply.
Replace Y701 
and/or C736. 
Replace the 
suspected 
components. 
Replace U702. 
Check D722, D723, 
C716, C717, C718, 
C719. 
No
Yes
Yes
Yes
Yes
No
Yes
No
No
Yes
No
No
Yes
Yes
Yes
Yes
No
No
No
No
No
No
Yes
Yes
No
Yes