Protection Circuit Description - Pioneer A-70DA-K Service Manual

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5.2 PROTECTION CIRCUIT DESCRIPTION

1. PROTECTION operation
A
Purpose of PROTECTION operation
 Protection of operation due to failure of product
 Protection of operation due to wrong use by a user
e.g.) Rare short of speaker connection is generated, or product is installed by
blocking the heat release hole
Detect the L/Rch independently for OVER LOAD, temperature and ZOBEL, and detect 2 ch
for the power PROTECTION (main unit side), and perform OR process by software.
1.1 DC DETECT
After DC DETECT is detected, MUTE ON & PROTECTION RELAY OFF are carried out.
If DC DETECT is detected for 3 seconds or more continuously, it is evaluated as "1.1.1 AMP failure" shown below.
B
If DC DETECT is detected for less than 3 seconds, it is evaluated as 1.1.2 SIGNAL CLIP" shown below.
1.1.1 AMP failure
After DC DETECT is detected, MUTE ON & PROTECTION RELAY OFF are carried out.
Prohibit the power is turned ON for 1 minute.
If DC DETECT is detected again when the power is turned ON next time, it is judged to be "AMP failure,"
and the power is turned OFF.
If the power supply is automatically turned OFF after AMP failure is detected, all key operations are
prohibited (Prohibit the power supply is turned ON).
For turning ON the power supply again, refer to "3. How to reset the prohibition of power ON" shown below.
1.1.2 SIGNAL CLIP
C
If DC DETECT is detected for less than 3 seconds, it is evaluated as "SIGNAL CLIP".
If the detection of DC DETECT is reset within 3 seconds, MUTE OFF & PROTECTION RELAY ON
are carried out.
NOTE) If the detection of DC DETECT is reset within 3 seconds and DC detection functions immediately,
PROTECTION RELAY OFF/ON is repeated, however, there is no problem.
1.2 OVER LOAD
MUTE ON & PROTECTION RELAY OFF are carried out immediately after the detection and the power is
turned OFF.
After OVER LOAD is detected, the key operation is not prohibited (the power supply can be turned ON).
NOTE) If a short of speaker cable may be generated, the connection is made again and the power supply
D
cannot be turned ON by a user, so a complaint is generated.
If AMP is broken actually, DC detection operates, so there is no problem.
1.3 Temperature PROTECTION
MUTE ON & PROTECTION RELAY OFF are carried out immediately after the detection and the power is
turned OFF.
Prohibit the power is turned ON for 1 minute.
NOTE) After the detection, if the temperature is still high even by turning ON the power supply,
the temperature PROTECTION is detected again and the power supply is turned OFF.
1.4 Power PROTECTION
MUTE ON & PROTECTION RELAY OFF are carried out immediately after the detection and the power is
E
turned OFF.
If the power supply is automatically turned OFF after the power PROTECTION is detected, all key operations are
prohibited (Prohibit the power supply is turned ON).
For turning ON the power supply again, refer to "3. How to reset the prohibition of power ON" shown below.
1.5 ZOBEL PROTECTION
MUTE ON & PROTECTION RELAY OFF are carried out immediately after the detection and the power is
turned OFF.
After ZOBEL is detected, the key operation is not prohibited (the power supply can be turned ON).
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