Hello,
I have a Class D amplified speaker I am trying to fix (circuit attached).
The fault at the moment is that when the speaker is powered on, and with no input signal, one of the speaker channels half-bridge configured FET's begin to immediately overheat. Hot enough that it turns the solder on the Drain tab molten.
To prevent damage to the speaker while diagnosing the fault, I have disconnected the HV + and - rails and just have the lower voltage IC's and pre-amps working.
Now when I feed a sine wave into the input of the circuit, I can trace it all the way up to [IN HI] and [IN LOW] inputs on pin 13 of U9 and U10 (audio drivers on page 3 of attached pdf). The problem is, this signal is still just a clipped sinewave and not a PWM signal.
So as per the title, can anyone tell me where the PWM from running a Saw Tooth wave and input signal into a comparator in the circuit is occurring ?
This still may not be related to the actual fault but I am first just trying to get my head around the circuit.
I have a Class D amplified speaker I am trying to fix (circuit attached).
The fault at the moment is that when the speaker is powered on, and with no input signal, one of the speaker channels half-bridge configured FET's begin to immediately overheat. Hot enough that it turns the solder on the Drain tab molten.
To prevent damage to the speaker while diagnosing the fault, I have disconnected the HV + and - rails and just have the lower voltage IC's and pre-amps working.
Now when I feed a sine wave into the input of the circuit, I can trace it all the way up to [IN HI] and [IN LOW] inputs on pin 13 of U9 and U10 (audio drivers on page 3 of attached pdf). The problem is, this signal is still just a clipped sinewave and not a PWM signal.
So as per the title, can anyone tell me where the PWM from running a Saw Tooth wave and input signal into a comparator in the circuit is occurring ?
This still may not be related to the actual fault but I am first just trying to get my head around the circuit.
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