After playing the AP5.9bit audio for more than 20 minutes, a large current appeared, and the power MOS tubes (Q21, Q22, Q27, Q28) were severely heated and burned out. Measure the waveforms of pins 9 and 10 of TL494 with an oscilloscope. The frequency is normal at 46KHz, but the duty cycle is abnormal and very small. It is abnormal for the fourth pin to have a voltage of 1.7V. Finally, it was discovered that the damage was caused by the nearby capacitor C36. C36 is a capacitor on the 14 pin reference voltage output, which is constantly charging and discharging, causing a constant voltage on pin 4 and changing the duty cycle. I hope this can help people who have encountered the same problem
Audison AP5.9 bitAfter more than 20 minutes of startup, the high current burns the power MOS transistor
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