Protection Circuit - Pioneer X-HM81-K Service Manual

5

5.2 PROTECTION CIRCUIT

If a protection circuit is activated then the unit enters Standby mode, the LED flashes in accordance with the activated
protection function, as shown in the table below.
LED flashing time
Protection
LED ON
DC 100 msec
POWER 500 msec
AMP 100 msec
OVER TEMP1 100 msec
OVER TEMP2 100 msec
PWM 900 msec
BT (*) 100 msec
USB 100 msec
If the DC, POWER, or PWM protection circuit is activated, operation of the unit will be locked.
The buttons that can be used to release operation lock are as follows:
Simultaneously press the "INPUT" and "np" (Tune Up, Skip Up) buttons on the front panel,
or simultaneously press the "STANDBY/ON" and "g" (STOP) buttons on the front panel.
After operation lock is released and the unit is then turned ON, the unit will perform the following:
• Count the number of activations of protection circuits
• Cancel flashing of the LED
Description of Each Function
• DC Protect
The DC outputs from AMP_OUT_L and AMP_OUT_R are detected to avoid DC current surge to the speakers and excess
voltage at B+ (+33 V).
The protection circuit is activated when the signal at Pin 3 of IC601 changes from H to L.
D
MAIN ASSY
M3V3_SW
MAIN_MICOM
3 DC_PROTECT
IC601_3 pin
DC_PROTECT
5
6
Operation
Lock
LED OFF
900 msec Lock
500 msec Lock
100 msec —
100 msec —
100 msec —
100 msec Lock
100 msec —
*X-HM81,XC-HM81 only
100 msec —
D620
KDS4148U
MTZ22B
X-HM81-K
6
7
C731
R824
100N-K
100K
R826
47K(1/4)
Q636
KTC3198
7
8
A
B
C
D
R827
10K
E
F
21
8