Yamaha RX-V3900 Service Manual page 35

When there is a history of protection function due to a
short between speaker terminals
Cause: The line between speaker terminals is shorted.
Supplementary information: As the excess current is
detected after operation of the speaker relay, the shorted
speaker terminal and the connected speaker can be
identified.
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.
Cause: The voltage in the power supply section is abnormal.
(Normal value: PS1 43 to 66, PS2 107 to 133,
PS3 140 to 179)
Supplementary information: The abnormal voltage is
displayed in based on 5V as 255.
Turning on the power without correcting the abnormality
will cause the protection function to work 1 second later
and the power supply will be shut off.
Note)
• Applying the power to this unit without correcting
the abnormality can be dangerous and cause ad-
ditional circuit damage. To avoid this, if protection
function has been activated 3 times continuously,
the power will not turn on even when the "MASTER
ON/OFF" switch 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 of this unit.
• Amplifier current should be monitored by mea-
suring DC voltage across the emitter resistors for
each channel.
When there is a history of protection function due to a short between speaker terminals
When there is a history of protection function due to abnormal
voltage in the power supply section
A/D conversion value of voltage
Firmware version
Firmware version
RX-V3900/DSP-AX3900
35