Motorola ASTRO Digital Saber - Page 104

10-22
Chart 34 . 800MHz Voltage Controlled Oscillator (VCO)
VCO TX/RX Unlock
MAEPF-24388-A
NO
VDC
U307-9
VDC
U302-19
VDC
U302-20
VDC
U302-17
NO YES
Check Continuity
Between
U302-19 &
U307-9
YES NO NO
YES
5VDC
U307-3
777-825MHz
Change U302
5VDC
U303-6
806-825MHz
VDC
U303-3, 13
NO
YES
YES
NO
5VDC
U307-8
850-870MHz
Measure
Freq.
U303-15
Measure
Freq.
U302-21
Refer to FGU
Chart C.32
VDC
U307-1, 7
Change U307
5VDC
U302-38
806-825MHz
Check Continuity
Between
U302-38 & U303-6
Refer to FGU
Chart C.32
YES
NO
YES
NO NO
YESYESYESYES
NO
Check C310 if
OK Change
U302
Refer to
Chart DC
Switch C.37
Check L301,
C377 if OK
Change U303
NO
NO
Chart 35 . 800MHz DC Switch
800MHz DC Switch.
Voltage at
Q503-4?
Check
continuity
between U305
and Q503.
Refer to Chart
C.5 on "DC
Supply Problem".
Yes
No
Yes
No
No
No
MAEPF-24392-A
Yes
Yes
Yes
VDC at J1-17?
Check mating
plug. If plug is
good, go to
chart C.26.
VDC at U305?
Replace U305.
Voltage at
U305-1?
Check U503.
0V at Q503
Pin 5 - RX
Pin 3 - TX?