(Vhf/Uhf Frequency Generation Unit - Fgu) - Motorola Handie-Talkie MTX Series Theory/Troubleshooting Manual

Check Continuity
between J1-17 &
J104-17, J1-15 &
J104-15,
J1-5 & J104-6
if No Fault Found
Replace U204
No 2.1 MHz
Go to VCO TX/RX
Unlock
Troubleshooting
Chart #5A
Check CR205,
CR206, C266, C267,
C284 & C285(V),
C282, C259
40
TROUBLESHOOTING FLOW CHART #4A

(VHF/UHF Frequency Generation Unit - FGU)

FGU No Lo Injection/TX
Unlock
VDC at
YES
VCTRL (TP5),
<0.7V?
NO
5V at
NO
U204
Pin 20, 23,
25, 41?
YES
VDC at
NO U204 Pin 21,
28(Tx), 29(Rx)
37 & 38
OK?
YES
13V at
U204
Pin 35?
YES
2.1 MHz
NO
at U204
Pin 11?
YES
YES
VDC at
CR205 Pin 4
OK?
NO
YES NO
2.5V at
U204
Pin 7 & 8?
Replace
U204
YES
VDC at
U202 Pin 1,
2 & 8 OK?
NO
Replace Replace
U202 U204
16.8 MHz 16.8 MHz
NO
at U204 at U203
Pin 14? Pin 10?
YES
Check Connection
2.5V at
U204
at C274, R221(V),
Pin 14?
R222(U)
YES
IC
U202
Check C256,
C257, C258 & U204
CR204
Replace
U204
CR205
YES
NO
OK
Replace
U203
PIN VOLTAGE
1, 2 5V
8 7.5V
21 1.6V
28 1.7V (VHF TX)
28 1.6V (UHF TX)
29 1.8V (VHF RX)
29 1.6V (UHF RX)
38 4.5V (TX)
38 0.7V (RX)
37 4.5V (HIGH END)
37 0V (LOW END)
4 -7.5V (HIGH END)
0V (LOW END)
MAEPF-23272-O