Yamaha HTR-6150 Service Manual page 24

RX-V563/HTR-6150/DSP-AX563
When there is no history of protection function:
When there is no protection history
NO PROTECTION
When there is a history of protection function due to excess current
Cause: An excessive current flowed through the power amplifier.
Supplementary information:
As current of the power amplifier is detected, the abnormal channel can be identified by checking the current
detect transistor.
Turning on the power without correcting the abnormality will cause the protection function to work immediately
and the power supply will instantly be shut off.
Note)
• Applying the power to this unit without correcting the abnormality can be dangerous and cause additional
circuit damage. To avoid this, if "PRI" and "PRD" protection function has been activated 3 times continuously,
the power will not turn on even when the "STANDBY/ON" 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 power amplifier channel should be checked for damage before applying power to
this unit.
• Power amplifier current should be monitored by measuring DC voltage across the emitter resistors for each
channel.
When there is a history of protection function 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.
If the power is turned on with the abnormality unsolved, the protection function works in 3 seconds to turn off
the power.
24
After a few seconds
PRI PRT:xxx
AD value when the protection function is working
PRD PRT:xxx
AD value when the protection function is working
A1.ANLOG BYPAS