Ericsson LBI-31511B, Maintenance Manual, Page: 5 / 18

TROUBLESHOOTING PROCEDURE
SIGNAL INDICATION VOLTAGE LEVEL
CAS
RUS
Sq Dis, Input
CCT Sq Dis, Input
TX Enable
PTT, Input
High Level
Low Level
High Level (RX Un-sq)
Low Level (RX Squelched)
Low Level (RX Mute/PTT)
Pulled low (RX unsquelched)
Logic Low (Sq. Dis)
Logic High (Sq)
RX Un-Sq
Logic Low
Logic High
Logic Low
Logic High
Logic Low
Logic High 9.0 Vdc
0.15 Vdc
9.0 Vdc
0.15 Vdc
0.6 Vdc
0 Vdc
2.4 Vdc
0.14 Vdc
0.35 Vdc
5.5 Vdc
2.0 Vdc
9.0 Vdc
1.0 Vdc
13 Vdc
CURRENT REFERENCE CHART
SERVICE
PLUG
FUNCTION TYPICAL CURRENT/mA
P701
P702
P703
P704
P705 5V
9V
9V
9V
9V 75
70
TX 90, RX 80
TX 45, RX 75
TX 40, RX 55
TEST POINT DATA (Typical)
TEST POINT VOLTAGE CONTROL DESCRIPTION
J602-3
9.0
±
0.05 Vdc
R703 9 Volt Regulator
J602-2 13.2 Vdc (A+)
J202 3.0-7.5 Vdc C220 (RX)
L209 (TX) VCO Control Voltage
(See Synth Align)
J353 0.7 VPP Reference Osc. Output (high
impedance)
J352 5.5 Vdc (Nominal) Reference Oscillator
compensation line voltage
J712 5.0 Vdc VCC to Microcomputer
(Cont.)
TYPICAL PERFORMANCE INFORMATION
SIGNAL LEVELS
(Cont.)
TYPICAL PERFORMANCE INFORMATION
RADIO CONNECTOR IDENTIFICATION
Front Connector
Systems Metering
Option Connector
PROM Program Plug
RF Metering
RX Input
IF Input
RX Inj.
Exciter Input
Exciter Output
Hand Programmer Enable
Program Disable
TX PA Metering
VG Interface
Fixed Squelch
Channel Guard
Aux Audio
DPTT
IGN A+ J601
J602
J603
J711
J101
P401
P404
P451
P102
P101, P103
P706
P707
J1
P612
P605
P608
P610
P402
P403
TRANSMITTER QUICK CHECKS
–
Connect red system metering plug to J602, system metering.
–
Connect black plug of GE Test Set to RF Metering jack J101. Set polarity to "+" and voltage range to the 1 volt
position (Test 1).
EXCITER
RANGE
POSITION
RF METERING J101
EXCITER READINGS
PROBABLE CAUSE
METERING READINGS
TEST
POS. METERING
JACK J101
FUNCTION
METER
SCALE
TYPICAL
READING
HIGH LOW
TEST 1 A J101-10 AMPL-1 0-1 0.2V
Q101
Shorted
R 1 0 1 , R 1 0 3
Open Q101 Open; R103, R105,
O p e n ; L 1 0 3 O p e n ;
O s c i l l a t o r / B u f f e r
Defective
TEST 1 B J101-9 TRIPLER 0-3 0.2V
Q102
Defective; R107
Open Q102 Shorted; R110 Open;
L104, L105, and associated
c i r c u i t s , d e f e c t i v e o r
improperly tuned.
TEST 1 C J101-8 AMPL-3
REL PWR
OUT
0-1 0.5V
H e l i c a l C o i l
L114
Shorted Or
Mis-tuned Q103 OR Q104 defective.
Check resistors, capacitors
around Q103 and Q104.
Helical coils L107, L108
m is - t un ed o r de f ec ti v e.
D 1 0 1 a n d a s s o c i a t e d
metering circuits defective.
RECEIVER READINGS SYSTEM JACK, J602
TEST POS FUNCTION SCALE
TYPICAL
READING
D IF AMP 1V 0.75
H RX INJ 1V 0.55
LBI-31511 LBI-31511
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