Specifications

56
IF R98 & C101 AND R13
& C5 ARE OK, THEN
TROUBLESHOOT VCO
ARE
C1, C2, C3,
C4, C18, R9,
R10 & R11
OK?
ARE
EXT. CHARGE
PUMP(Q3~Q6)
CIRCUITRY
OK?
IC2 BAD
REPLACE OR
RESOLDER
NECESSARY
COMPONENTS
REPLACE OR
RESOLDER
NECESSARY
COMPONENTS
IS D903 PIN1
>15.0VDC?
OPEN R12 AND
THEN CHECK
VOLTAGE AT
D903 PIN1
START
VISUAL
CHECK OF
THE BOARD
OK?
CORRECT
PROBLEM
+5V AT IC2
PINS 3 & 4?
CHECK 5V
REGULATOR
IS 12.8MHZ
SIGNAL AT
IC2 PIN1?
CHECK R14 &
C8
IS 12.8MHZ
SIGNAL AT
TCXO1 PIN1?
YES
ARE
SIGNALS AT
PINS 15 OR 16
OF IC2?
ARE
WAVEFORMS
AT PINS 15,16
SQUARE?
IS
THERE ANY
SHORT BETWEEN
AROUND
CIRCUITRY AND
PIN 15 & 16
OF IC2
IC2 BAD
REMOVE
SHORTS
DO PINS 9, 10
& 11 OF IC2
TOGGLE WHEN
CHANNEL IS
CHANGED?
IS INFORMATION
FROM uP IC401
CORRECT?
CHECK uP
IC401
CHECK
PROGRAMMING
LINES BETWEEN
IC401 AND IC2 PINS
9, 10 & 11
IC2 BAD
IS RF LEVEL
AT IC2 PIN 8
BETWEEN -15
& +5DBM?
CHECK VOLTAGE
DOUBLER(TRIPLER)
SD-161/171 : USE VOLTAGE TRIPLER
SD-164/174 : USE VOLTAGE DOUBLER
YES
YES
YES
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NONO
YES YES
YES
NO
NO
NO
NONO
NO
IF PIN1(MOD) AND
PIN4(B+) OF TCXO1
ARE 1.9VDC AND
5.0VDC, RESPECTIVELY
THEN REPLACE TCXO
Figure 9.3. Troubleshooting Flow Chart for Synthesizer