When The Protection Function Worked Due To Abnormal Dc Output - Yamaha R-S300 Service Manual

2-2. When the protection function worked due to abnormal DC output.

Cause: DC output of the power amplifier is abnormal.
Supplementary information: The protection function worked due to a DC voltage appearing at the speaker terminal.
A cause could be a defect in the amplifier.
Turning on the power without correcting the abnormality will cause the protection function to work in 3 seconds and the
power supply will be shut off.
2-3. When the protection function worked due to abnormal voltage in the power supply section.
Cause: The voltage in the power supply section is abnormal.
Supplementary information: The protection function worked due to a defect or overload in the power supply.
Turning on the power without correcting the abnormality will cause the protection function to work in 1 seconds and the
power supply will be shut off.
Notes)
• Applying the power to this unit without correcting the abnormality can be dangerous and cause additional
circuit damage. To avoid this, if "PS" and "DC" protection function works 3 times consecutively, the power
will not turn on even when the " " (Power) key is pressed. In order to turn on the power again, disconnect the
power cable of this unit from the AC outlet once and then reconnect it again.
• The output transistors in each amplifier channel should be checked for damage before applying power to this unit.
• Amplifier current should be monitored by measuring DC voltage across the emitter resistors for each channel.
2-4. When the protection function worked due to excessive heatsink temperature.
Cause: The temperature of the heatsink is excessive.
Supplementary information: The protection function worked due to the temperature limit being exceeded. Causes could
be poor ventilation or a defect related to the thermal sensor.
Turning on the power without correcting the abnormality will cause the protection function to work in 1 seconds and the
power supply will be shut off.
● History of protection function
When the protection function has worked, its history is stored in memory with a backup.
Even if no abnormality is noted while servicing the unit, an abnormality which has occurred previously can be defined
as long as the backup data has been stored.
For details, refer to main menu 6 PROTECTION HISTORY.
D C P R T : x x x H
AD conversion value when the protection function is working
P S P R T : x x x L
AD conversion value when the protection function is working
T H A P R T : x x x H
AD conversion value when the protection function is working
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