Motorola Astro Digitalport Saber Troubleshooting 68p81076c10 A Manual

							 
10-21 
Chart 33 . VHF/UHF Voltage Controlled Oscillator (VCO)
VCO TX/RX UNLOCK
Check
VDC at
C246
(VCTRL)
VDC
13V/0.7V/
Drifting
?
4.6V at
Collector
of Q202? Replace
U201
For VHF
check L217.
If OK
replace
U201.
Power at
collector of
Q202?
Voltage
at U204
Pin 21? Check
U2040.1V at
U201
Pin 7?
Is L207
(UHF) 208/209/
210/219
open?
0.7V at
U201 Pin
5?
Is
C235-C241,
CR207 (UHF)
CR201
open
Replace components & go
to -VEE crossover freq.
tune procedures Chart
C.39 except if L208, L209
are changed.
Check L205 &
R220. If no fault
found, replace
U201.3.3V
@ C211?Check
L221 &
U204
Check
R203, R204,
R205, R209,
& Q202
Replace
U201Replace
U201
Replace
U201
Replace
U201 Check
L221 &
U204 4.4V at
U201 Pin
5?
Is
C219, C220,
C222, C223,
C226, C227,
C270, CR203
open
0.1V at
U201
Pin 14?
Is
L215, L216,
L211, L213,
openUHF?Voltages
at U201 pins
11 and 12
ok?
Voltages
at Q203
ok?Check
R209, R206,
R217, R219
& R210
Check
R206, R217,
R219, R210,
R203, if ok
replace Q203
Replace components & go
to -VEE crossover freq.
tune procedures. Chart
C.39 except if L213, L215
are changed.
NOTE: If C240 is found 
defective, change to 2.7PF (VHF)/
2.4PF (UHF1)/2.4PF (UHF2)*
RX
ONLYTX
ONLYNOTE: If C240 is found 
defective, change to 2.7PF (VHF)/
2.4PF (UHF1)/2.4PF (UHF2)
*
NO
NO
NO YESYES
YES
YESNO
NOYESYESYES
YESYESYES
YES
YESYES
YES YES
TXRX
NO NO
NO NO NO NO
NO NO NO YES
* *
MAEPF-24387-A
NO
NO 
						

							 
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
YESNO YES
NO NOYES YES YES YES
NOCheck C310 if
OK Change
U302 Refer to
Chart DC
Switch C.37
Check L301, 
C377 if OK
Change U303 NONO
 
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
YesYes
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? 
						

							 
10-23 
Chart 36 . VHF/UHF DC Switch
No R5
U106 Pin 2Voltage
at U106
Pin 8?Voltage
at Q107,
Pin 2?Voltage
at Q107,
Pin 3?Voltage
at Q107,
Pin 4?
7.5V at
U202
Pin 8?5V at
U102
Pin 1?Less
than 4.8V
 at U106 
Pin 3?
Replace
U106
Check DC Power
Supply Failure
Chart C.5Replace
Q107 Check L131,
L121 and CR109
and L122 For 
Open Connections
YES
YES
YESYES
YES
NO
YES NO
NO
YES
NO NONO
Replace
U102
Replace
U202
No T5Voltage
at Q111 Pin
 3 collector?Voltage
at U202,
Pin 8?
Replace
U102Go to
Chart C.26
Replace
U202
Check Fuse, 
Flex Connection 
J1-17, 19, 20;
Volume Switch
Less than 
4.8V at Q111
Pin 1 base?5V at
U102
Pin 1?Voltage
at U202
Pin 8?
Check
conn. J1,
R101, and
header
good?5V at
Pin 3
of U102?
Replace U202
Rectify
Fault
Replace
Q111
YES
NO
YES
YESNO
YESYES
NONO
NO
MAEPF-24391-O
NONO YES
YES
••••••••••••••••••••••••••••••••••••••••••••• 
						

							 
10-24 
Chart 37 . 800MHz Transmitter RF
No/Low Power
Replace
Ant Switch
YES
NO
Check
Continuity at
Ant. Switch
NO BAD BAD GOODGOOD GOOD BAD
Check L102,
L105, C114,
C101, C108
Replace U501
Go to VCO
Chart C.34
Go to DC Switch 
Chart C.35
NO
YESCheck E1, E2,
E3, E4, J3
Check Q502
& R509
Go to VCO
Chart #5B
Replace U502
Check R507,
R508 NOYES
YESNO
NO YES NO
YES NO
YES YES YES
NO NO
YES YES
NONONO
GOOD
YES
NO
Check U503
D/A ICVDC
U502-2, 50.37 VDC
U504-12 VDC
U502-1 VDC
U502-3, 4 VDC
Base Q501 VDC
U502-7
VDC
U504-21VDC
U504-2
VDC
U503-11Check: U504,
CR501, R505,
C503, R503,
R506OHM\
Q501 VDC
U504-7
Check U504
ALC IC Check U503
D/A ICVDC
at
Q503
RF
Input Drive
U502-1
>1dBB+ VDC
U502-6
Check Continuity
Between U504-13 
& J3-20Change ALC
U504
YES
YESNO
See Chart C.32
FGU UnlockCheck U503
D/A ICCheck R501
MAEPF-24394-A
YES
YESNO NO NO 5 VDC
U504-11
VDC
Lock Det
Cath.
CR502
VDC
U503-3VDC
U504-13 Check RF @
RF Connector
J2Check
Continuity
across
U501RF
Input Drive
U502-1
>1dBmTX
Current
>500 mA
YES
NO
Check
L101 
						

							 
10-25 
Chart 38 . VHF/UHF Transmitter RF
No/Low Power
TX Current
> 500 mA?
RF at RF
Connector,J2
Pin 2?
Replace U105
NOYES
RF at 
Cathode of
CR108?RF Present
at Anode
of CR108?RF Present
at Pin 5 of
U104?
Replace U104Check Antenna
Switch Biasing
Circuits, L122,
L105, U101Check Components
Between C147
and L128Check antenna
switch
YES
YES
YES
YESNO
NO
NO
Is T5 On
at C153?B+ at 
U105, Pin 5
(VHF)
5,6 (UHF)?
Replace U105
7.5V at
U105
Pin 2.4?Voltage
at U105
Pin 3?RF Voltage
at U105,
Pin  1?
Check Components
Between U105
and U201. If No
Fault Found, 
Go To FGU 
Troubleshooting
Chart C.31
YES YES YES
YES YES
NO
Go to DC Switch
Routine Chart C.36Check B+, E1 & E101
(VHF), E1, E2, E3 &
E101, E104 (UHF) and
Power Supply
7.5V at
U105
Pin 2,4?Voltage
at U105
Pin 3?RF Voltage
at U105,
Pin  1?
7V at
Collector
of Q101?5V at
U101,
Pin 16?7.5V at
Emitter of
Q101?
Check L102, L103 (UHF)
L102, L130 (VHF)
Voltage at
Q101 Base
is B+ Less
0.7V?
Go to FGU No Lo 
Injection/TX Not
Lock Routine 
Chart #4ACheck Power
SupplyReplace Q101Replace U101
Voltage at U101
Pin 14 > 1V?Replace U102
Check Detector
Circuit, CR102, (VHF),
CR101 (UHF), CR103,
R110, R111, U102 YES
NO
Replace U101
U101, 
Pin 2,7
About 2.5V 
to 4V?
U101
Pin 3 
About 3.5V
Pin 6 
About 1.5V?
NO
YES
NO NO
NO
NO
NOYES
NO
YES
YES
NO
NOYES YES NO
NO
MAEPF-24393-O 
						

							 
10-26 
Chart 39 . VHF/UHF Only, VCO Crossover Frequency Tune
VCO-VEE Crossover
Freq. Tune ProcedureProgram Radio to 
Low Band Edge 
136 MHz (VHF)
403 MHz (UHF1)
450 MHz (UHF2)
Is
VCTRL (TP5)
>3.0V?YES
MAEPF-23274-B
NO
Program Radio to 
High Band Edge
178 MHz (VHF)
470 MHz (UHF1)
520 MHz (UHF2)
Is
VCTRL
>11.0V?
Program the New 
Crossover Frequency 
into the CodeplugIs 
VCTRL
2.5V to 3.5V?
Replace C240 or C223 
*
Use Up/Down Buttons
to Tune Crossover 
Frequency w/RSS
VHF
3.0
2.7UHF1
2.7
2.4UHF2
2.7
2.7 C240(RX)
C223(TX)
Replace C240 or C223 
*
VHF
2.4
2.0UHF1
2.0
1.6UHF2
2.0
2.0 C240(RX)
C223(TX)
Enable -VEEE
Crossover Point
Tune Mode w/RSS
YES
NO
NO
YES
A complete part description and
Motorola part number for ordering
is located in the service manual.*