Amplifier System Protection Operation Specification - Pioneer VSX-518-K Service Manual

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5.3 AMPLIFIER SYSTEM PROTECTION OPERATION SPECIFICATION

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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
The abnormality continues for 3 seconds.
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.
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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,
The abnormality continues for 3 seconds.
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on, speaker relay is turned off, then
"AMP_ERR" flashes on the display.
↓
↓ Continues.
The power is shut off.
↓
speaker relay is turned off, then
"OVERLOAD" flashes on the display.
↓
↓ Continues.
The power is shut off.
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*A.MUTE : Audio mute command
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The power is shut off even if the
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↓ Recovery
The program restarts.
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↓ Recovery
unit recovers.
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