History Of Protection Function - Yamaha DSP-AX2 Service Manual

In the case where the protection function works after DIAG has been started and the power is turned off ;
When the protection function (*2) works, the history of the protection function appears on display and the power
turns off. Repair the faulty parts according to the displayed history.
(*2) When an excess current or any other faulty condition is found with the power source, DC, etc., the protection
function forces the power to turn off.
I PROTECT
XXXXXXXX A:XXXX
PS PRT :000 X
XXXXXXXX A:XXXX
DC PRT :000 X
XXXXXXXX A:XXXX
TMP PRT:000 X
XXXXXXXX A:XXXX
Besides the above possible causes, the cause may exist in the disconnected connector or around CPU.
PS PRT, DC PRT and TMP PRT displays include the abnormal A/D value in % (voltage value obtained by consid-
ering 5V as 100%). Concerning this value, refer to DIAG menu No.10 FAN/AD described on page 22.

History of protection function

When the protection function has worked, its history is stored in memory with a backup. Even when no abnormality is noted while
the unit is being serviced, an abnormality which has occurred previously can be defined as long as the backup data has been
stored.
The protection history is cleared when DIAG is canceled by selecting "RESERVED" (memory initialization) from the setting items of
the DIAG menu No.9 PRESET or when the backup data is erased.
I PROTECTION display
(When the power is turned on without an abnormality corrected, the protec-
X
tion function works the moment the power relay is turned on to shut off the
power supply.)
Cause: There is an abnormal current flow to the power amplifier.
Supplementary information: As the current of the power transistor of
each channel is detected, the abnormal channel can be identified by
checking the current detect transistor.
Reference: If I PROTECTION function has worked after SP relay ON, a
warning message "CHECK SP WIRES" appears the next time the power is
turned on. This indicates that some trouble exists after the SP terminal,
such as a short-circuit of the speaker cable.
PS PRT display
(When the power is turned on without an abnormality corrected, the
protection function works about 1 second later to shut off the power supply.
Display may not be provided, if there is an abnormality with the power
supply for the display.)
Cause: There is an abnormality in the power supply section (voltage).
Supplementary information: As the power from following sources is
detected, it is possible to determine where an abnormality exists.
Transformer secondary winding
Stabilizing power source
DC PRT display
(When the power is turned on without an abnormality corrected, the protec-
tion function works about 3 seconds later to shut off the power supply.)
Cause: A DC output from the power amplifier of each channel is detected.
TMP PRT display
(When the power is turned on without an abnormality corrected, the protec-
tion function works about 1 second later to shut off the power supply.)
Cause: The temperature of the heat sinks in the power amplifier is
detected. When the temperature rises and an abnormality is detected, the
power turns off.
VI X 2(CB358), OR x 2(CB359)
±12, ±5V, +5D1, +5D2, VP
DSP-AX2
10