Yamaha A-S701 Service Manual page 25

Notes:
• Applying the power to this unit without correcting the abnormality can be dangerous and cause additional circuit
damage. To avoid this, if protection function has been activated the number of times which is set beforehand, the
power will not turn on even when the "z" (power) switch is pressed.
• 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.
• When turning on this unit again:
1. Remove the top cover.
2. While pressing the SW501 of FUNCTION (1) P.C.B., press the "z" (power) switch. (Fig. 21)
This unit starts the self-diagnostic function mode.
* When you start the self-diagnostic function mode by pressing SW501 for 3 seconds or more, the function will start
in the protection cancel mode. (Except when the current protection function is working.)
After the Protection Cancel mode is started, the "LINE 1" indicator flashes. (Fig. 22)
PS (Power Supply) protection:
If protection function has been activated 3 times consecutively, the power will not turn on.
I protection L/Rch:
If protection function has been activated 1 time, the power will not turn on.
* However, the power turns on when the protection function worked due to short at the speaker terminal.
Amplifier DC voltage protection L/Rch:
If protection function has been activated 3 times consecutively, the power will not turn on.
THM protection L/Rch:
The power turns on no matter how many times the protection function has worked.
Diode THM protection:
The power turns on no matter how many times the
protection function has worked.
FUNCTION (1) P.C.B.
Fig. 21
Fig. 22
A-S701
SW501
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