(800/900Mhz Receiver Rf) - Motorola Handie-Talkie MTX Series Theory/Troubleshooting Manual

Replace
U5
Check Comp. Check
YES
L32, L34, L10, VDC
C4, C27 & C11 Pins 3 & 4
Ok Replace U1
Check L8 OK
Refer to DC
Switch Chart #3B
TROUBLESHOOTING FLOW CHART #2B

(800/900MHz Receiver RF)

No-High SINAD
Inject
73.350MHz
NO
at Pin 1 FL1
-110 = 12dB
SINAD
YES
Inject
73.350MHz
at L20/C35
-113-12dB
SINAD
NO
YES
Inject
Carrier at
NO
Pin 2 of U5
12dB SINAD
-108dBm
YES
Inject
Carrier
NO
Pin 1 U5
12dB SINAD
-104dBm
YES
Inject
Carrier
NO
Pin 2 U4
-117dBm=12dB
SINAD
NO
YES
Inject
Carrier
Pin 1 U4
-113 = 12dB
SINAD
Inject
Carrier
Pin 1 S101
-116 = 12dB
SINAD
YES
Replace
J401
VDC at
Check
NO
Pin 18 U3
Freq.
0 or 5V
Pin 14-U3
YES
Check U3 &
Ext. Comp.
Check Comp.
FL1, L20,
C35 & C36
VDC
NO Refer to
Pin 4, 6, 11
DC Switch
U2 Chart #3B
YES
VDC
NO
Check T1 OK
Pin 1-15
Change U2
U2
Check
NO
Check C204 OK
RF Level +
Refer to
Freq. of Lo
Chart #5B VCO.
in -6dBm
YES
VDC NO
Replace
Pin 10-U2
U2
YES
NO
VDC
Check C84 OK
Pin 12-U2
Replace U2
YES
Check C82,
C90, C91 OK
Replace U2
Remove L30,
NO
C12 & recheck if
still bad.
Replace U4
Check S101,
NO
C151, L127,
C149, CR109
& C141
MAEPF-23442-O
Check Comp.
YES
Q1, CR5, C54,
C55, L24, C56
& C57
NO
37