Check the main power after power, sub-polar output voltage 133V so normal, normal power supply, estimated the protection circuit, check the socket on the motherboard D1 (7) feet 0V, 3V or so normal, indicating that protective action, check Q854 base 0.7V, not normal, frame protection signal D2 is disconnected socket (5) of the foot, boot Q854 base 0.7V disappearance is 0V, frame circuit exception, check the boot base Q401 extremely 0V, again frame circuit

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