Motorola ASTRO Digital Saber Service Manual page 103

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