Amplifier System Protection Operation Specification - Pioneer VSX-918V-K Service Manual

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5.3 AMPLIFIER SYSTEM PROTECTION OPERATION SPECIFICATION

1. DC-abnormality detection
DC detection is only enabled 2 seconds after power-on.
If there is a fault in the power amplifier or a high-level signal lower than 5 Hz is input,
the DC_DET port becomes "L".
If the "L" is detected, the microprocessor will perform as following flow chart.
In the case of simultaneous detection with the overload protection circuit,
DC-abnormality detection is performed preferentially to overload detection.
When a DC abnormality is detected, A.MUTE* is turned
on, speaker relay is turned off, then
"AMP_ERR" flashes on the display.
The abnormality continues for 3 seconds.
The power is shut off.
Power key not effective and POWER LED blinks (only for VSX-918V).
However, when the following keys are pushed so that the key input of a line and the service can
be carried out, power can be on.
1 TESTMODE ON (A55F+A55F)
2 When power off, push TUNE+ key + AUTO SURR/DIRECT key continuously 2sec.
(2: When a DC abnormality is detected and the power is shut off.)
Any other key input from front panel or remote control will not be detected.
2. Overload detection
If the speaker terminals are short-circuited or low-load driving is detected, the OL_DET port becomes "L".
If the "L" is detected, the microprocessor will perform as following flow chart.
When an overload is detected, A.MUTE* is turned on,
speaker relay is turned off, then
"OVERLOAD" flashes on the display.
The abnormality continues for 3 seconds.
The power is shut off.
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6
↓
↓ Continues.
↓
↓
↓ Continues.
VSX-918V-K
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*A.MUTE : Audio mute command
↓ Recovery
The program restarts.
↓ Recovery
The power is shut off even if the
unit recovers.
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8
A
B
C
D
E
F
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