• Applying the power to a unit without correcting the
abnormality can be dangerous and cause additional
• The output transistors in each amplifier channel
should be checked for damage before applying any
• Amplifier current should be monitored by measuring
across the emitter resistors for each channel.
Cause: The voltage in the power supply section is
Supplementary information: The abnormal voltage is
displayed in % based on 5V as 100%.
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.
* Additional causes of protection can be due to loose
c o n n e c t i o n s ( i n c l u d i n g g r o u n d ) , a s s o c i a t e d
components, CPU, etc.
• 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.
The history of the protection function is cleared when
DIAG is cancelled by selecting PRESET RESERVED
(Memory initialized) of DIAG menu No.9 or by selecting
Prt His < DEL (Protection history deletion reserved) of
sub-menu 6 of DIAG menu No.15 and the backup data
• Display during menu operation
During the DIAG operation, the function at work is
indicated on the FL indicator. The contents displayed
during the function operation are described in the later
section on details of functions
When there is a history of protection
function due to abnormal voltage in
the power supply section
Voltage display in %
Version (1 alphabet)