Yamaha 150 Troubleshooting

12
Troubleshooting
The following table lists the main causes of abnormal operation and the corrective measures required, as well as the
protective circuit operation in each case.
Protection CircuitRemedyProbable CauseIndicator
CLIP indicator lights.
PROTECTION
indicator lights.
There is a short at a
speaker terminal,
amplifier terminal, or
wire.
The amplifier load is
excessive.
The heat sink
temperature has
exceeded 90°C.
A DC voltage of ±2 V
or greater was
generated in the power
amplifier’s output
circuit.
Locate and correst the
cause of the short.
Check the amplifier
ventilation conditions
and take appropriate
measures to improve
airflow around the
amplifier.
Consult your dealer or
nearest Yamaha
service center.
The PC limiter circuit
operates to protect the
power transistors.
The thermal protection
circuit operates to
protect the power
transistors.
The relay operates to
protect the speaker
system.
Set the speaker impe-
dance to 32Ω or higher
with the OUTPUT VOLT-
AGE switch set to 70 V,
or to 64Ω or higher with
the OUTPUT VOLTAGE
switch set to 100 V.