PIONEER VSX-C400-S/MLXU
Service Manual

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7.1.5 Circuit Description
A

1 Protection circuit when the edge of speaker is oveload
R325 330 R317 0.22

3 FAN detection circuit
CN305 +5.6V R405 R407 10k 1k C402 0.01

POWER Assy A
FL

FAN+ FANFAN.STOP

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D401 R408 100k

B
R327 1.8k D301 Q305

To µ-COM FAN DCT

FRONT Assy
SP edge GND FL +5V R4243 10k To µ-COM ODCT

D410 UDZS5.1B

D303 DAP202K

When FAN is not connected between FAN+ and FAN-, or an alien substance is clogged up in the FAN at the FAN LOCK status, FAN STOP becomes the same electric potential as the FAN- (Low). � µ-COM detects it, and turn the power OFF.

B

A speaker (6�) is connected between FL and GNDFL normally. Q305 (306) (345) (346) (383) does not work because the voltage of A point is higher than B point. If a resistance value between FL and GNDFL becomes less than 1.2�, Q305 (306) (345) (346) (383) turns ON. And ODCT becomes with negative component of output level. � µ-COM detects it, and turn the power OFF.

C

2 DC detection circuit of SP terminal
R331 22k FL R332 22k FR R371 22k RL R372 22k RR DDCT R392 22k C R396 10k C391 220/10 Q384 Q385 +5V

POWER Assy
R4244 47k

D

FRONT Assy

� Q384 and Q385 are turning OFF together normally. (1) When the DC voltage of the plus (+) side was generated on the SP edge When the DC voltage of the plus (+) side was generated in L ch or R ch, Q384 turns ON and DDCT becomes Low level if VB of Q384 becomes higher than operating point. � µ-COM detects it, and turn the power OFF. (2) When the DC voltage of the minus (-) side was generated on the SP edge Q385 turns ON with + side in reverse, and DDCT works.

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F

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VSX-C100-S
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