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When inspecting an amplifier with a protective circuit, it should be seen whether the protective relay can be drawn after starting. If the relay does not operate, should measure the power amplifier circuit midpoint output voltage is not offset, overcurrent detection voltage is normal. If the overcurrent detection voltage is abnormal or the midpoint output voltage is offset, it indicates that the power amplifier circuit is faulty. Check whether the positive and negative power supplies are normal. If the positive and negative voltage are not symmetrical, the load circuit of the positive and negative power supply can be disconnected to determine whether the power circuit itself is abnormal or the power amplifier circuit is faulty. If the positive and negative power supplies are normal, check whether the amplifier tubes in the power amplifier circuit are damaged.
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If the overcurrent detection voltage and point output voltage in the power amplifier circuit are normal, and the maintenance relay is not drawn, the maintenance circuit presents shortcomings, check whether the drive tube or relay drive integrated circuit is damaged, and the detection circuit is normal. If the relay contact can be drawn, but there is no movement, check whether the speaker is normal, whether the relay contact is bad, and whether the noise squelch circuit is active.
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If the above are normal, and then use the signal nuisance method to check, see the power amplifier after the stage is still the previous stage circuit presents shortcomings
Boot protection is caused by the failure of the power amplifier. You can disassemble the power amplifier first do not power, use a multimeter to measure whether the power amplifier tube is broken down short circuit, each channel is measured.
If the active pipe short circuit is burning the pipe, this situation is very complicated, may damage a lot of components, return to the factory repair better. If there is no power amplifier short circuit check. Detect the working voltage and midpoint voltage bias voltage of the power amplifier board, which are all parameters to determine the quality of the power amplifier board. Fix what's wrong. Power amplifier protection is also very difficult to repair the fault, not familiar with the power amplifier maintenance or return to the factory maintenance.