More Complex Troubleshooting; Receiver - JBL JSR-400 Service Manual

Dolby Pro-Logic A/V Receiver
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Symptom
Receiver inoperative
Fuse blows when power is
turned on.
FL indicator lights but no sound
One channel does not work when
volume is at maximum with a test
Signal applied to the center
terminal of volume control VR1 of
The dead channel.
Speaker works normally but
Headphones inoperative.
FM inoperative
Poor multiplex separation
STEREO indicator does not light.

MORE COMPLEX TROUBLESHOOTING

Cause and Remedy
A) Faulty AC power cord. (FL indicator does not light) Replace.
B) Defective power switch. Replace.
C) Broken wire in the power transformer. Replace the power transformer.
D) Blown fuse. Replace the fuse.
A) Defective power transformer. Replace.
B) Short on the primary or secondary of the transformer circuitry. Repair the short.
C) Damaged rectifier (D20) or damaged "transistor (Q3, Q11, Q12)."
Replace the defective component(s).
D) Short circuit in the amplifier circuit. Replace the shorted component(s)
in the amplifier circuit.
A) Defect in IC3 on the Main Board. from both channels.
Replace the defective component(s).
A) "Defect in IC2,IC3 on the Main Board" signal applied to the center terminal
volume is at maximum with a test channel. Locate and correct the defect.
B) Break in copper foil of printed circuit board. Repair the trace.
C) Short in speaker output terminal. Repair or replace.
A) Headphone plug does not mate with jack. Replace the jack.
B) "Defective resistor R52, R53." Replace.
A) Defective front-end. (PACK1) Replace.
B) Defective FM switch. Replace the switch.
C) "Defective transistors Q1,Q2,Q3,Q201," "Q202 or IC2, IC3, IC4"
Replace the defective transistor(s) or IC(s).
D) Defective coil T4. Replace the coil(s).
E) Defective lead-in. Repair or replace the lead-in.
F) "Ceramic filters F101, F102 defective." Replace the defective ceramic filter(s).
G) Defective controller circuit component. Replace.
A) Improper adjustment. Readjust VR401.
B) IC4 defective. Replace.
C) Variable resistor VR401 defective. Replace the variable resistor.
A) Defective indicator in FL. Replace.
B) Defective IC4. Replace the defective component.
JSR-400
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