Troubleshooting - Realistic TRC-410 Service Manual

6. TROUBLESHOOTING
SYMPTOM
' CAUSE/REMEDY
A) UNIT WILL NOT
TURN ON.
1. Defective power switch S3: Replace.
2. Fuse blown: Replace.
3. Broken DC power cable: Replace.
4. Poor solder connection or other open connection in circuit:
Repair or replace.
5. Defective IC-1: Replace.
B) NO RECEIVE
SOUND.
1. Defective external Speaker jack: Repair or replace.
2. Poor contact on microphone connector: Repair as required.
3. Defective push switch on microphone: Repair or replace MIC.
4. Defective internal Speaker: Replace Speaker.
5. Defective D4, VR3, VR2, IC-3 or semiconductor in RX circuit:
Replace the defective component(s).
6. Defective VR-1: Replace.
C) NO NOISE
1. Defective Q7: Replace.
2. Measure transistor & IC voltages in all audio states and receiver
section. Compare with voltages noted on the IC Et TRANSISTOR
VOLTAGE CHART.
3. Improper local oscillator adjustment: Readjust.
4. Defective SQUELCH Circuit (IC-3, VR2, VR3): Replace the
defective component(s).
D) NO TRANSMISSION
1. Defective microphone: Repair or replace microphone.
2. Defective push switch on microphone: Repair or replace.
3. Improper adjustment of carrier oscillator or local
oscillator: Readjust.
4. If you have checked all channels and obtain no RF output, check
V.C.O. and/or signal trace through transmitter circuit.
5. Defective Antenna connector: Repair or replace.
6. Defective L1: Repair or replace.
7. Defective Q14 (E-C short): Replace.
E) NO MODULATION
1. Defective microphone: Repair or replace microphone.
2. Poor audio output/Defective modulator: Repair or replace
defective component(s).
3. Inoperative microphone amplifier (Q13, IC-4): Replace
component(s).
4. Defective microphone connector: Repair or replace.
5. Defective AMC circuit (Q11, D7, Q12): Replace component(s).
F) NO SQUELCH
1. Defective Q7, IC-3 circuit: Replace component(s).
2. Improper adjustment of VR-3: Readjust.
G) LED METER DOES NOT
OPERATE BUT CB
OPERATES NORMALLY
1. Defective LED (D11-1 - D11-5): Replace.
2. Defective IC-5: Replace.
3. Defective D3, VR-5: Replace.
H) MODULATION
INDICATOR
DOES NOT LIGHT
1. Defective D15, Q10: Replace.
2. Check Modulation: Refer E) NO MODULATION.