Multitone RPR 551IS - Page 81

SEND CALL
DECASE
AND PLACE
IN P637
CALL
RECEIVED?
CHECK
SENSITIVITY
RE-ALIGN
CHECK:
L2 - FAULTY OR
MISALIGNED,
IC1
FAULTY C13,
FL2
CHECK:
FL1, IC1
SHORT CCT
SK2 PINS 1, 4.
CHECK:
1V AT C18
INJECT
MODULATED
SIGNAL*
IS 1kHz
TONE AT
SK2 PIN 2?
REMOVE RADIO
PCB, INJECT
MODULATED 455kHz
≈5 V AT PL1 PIN 3
IS 1kHz TONE
AT SK2 PIN 2?
FAULTY RADIO
BOARD
IS 455kHz
AT IC1
PIN 5?
IS DATA
AT R17?
PAGER
OK
NO
YES
OK
>3dBm LOW
YES
YES
NO
NO
CHECK:
TR27, TR28,
TR3, IC1
PIN 19, R3
NO
YES
NO
NO
YES
CHECK:
DATA FILTER
AND LIMITER,
TR11, TR12,
TR13, IC1 PIN 16
CHECK:
GATE
ARRAY, SEE
TABLE 5
YES
NO
YES
B
* -70dBm CHANNEL FREQUENCY
1kHz MODULATION
1.5/3kHz DEVIATION
IS 455kHz
AT IC1
PIN 4?
OK
GO TO:
C FOR RPR 551IS
D FOR RPR 552IS
E FOR RPR 553IS
RPR 550IS Series
TM1188 Issue 1 Page 5 - 11
Figure 4: Fault-Finding Guide
(Continued)