Display system control circuit is working correctly, "failure" should be in the Dianyuan power supply circuit or the speaker protection circuit, measuring TA7317P four feet high, relay 3K1, 3K2 contacts are not snap analysis is the internal overload, overvoltage or the midpoint voltage offset. PIN voltage test TA7317P ①, ②, discovery II pin voltage -1.2V, normal should be 0V. Checks place, the voltage at the output of the surround amplifier integrated LM3886 is 0V, the midpoint of the left channel output of 0V, while the right channel the midpoint voltage of -4V, after looking up late-stage power amplifier tube 3VT15 (2SA1943) c-e junction leakage current, after replacing it "failed" excluded.58eservice manual download site