Is the square wave modulated when you drive a signal into the amp?
Modulation is when a square wave changes pulse width in relation to the input signal. With no modulation, it's a clean square wave. With modulation, it's mostly blurred.
This is a power supply being modulated. It's different because it's always less than 50% but you get the idea. It's only 640x480 resolution so if viewed full screen, it looks awful.
http://www.bcae1.com/temp/audioandpowersupply01.avi
How low is the muting voltage going on the driver board header?
The pin configuration should be the same as the SLA1500 but it has two fewer pins.
http://www.bcae1.com/temp/SLA1500.pdf
Upto the 5th pin of lm6172.You stated that you had audio on the driver board. How far into the circuit does the audio go? Where is the last point where you see the audio?
I dont have that to replace and check is there any replacement I can use?Is the 6172 defective? I don't see how the input pin of the op-amp could have signal on it without it affecting the output.
No change when the opamp change. Still no output.The 6172 is a high-speed op-amp. Others may work but may not perform as well. They may be sufficient for testing. Don't damage the 6172 if you try changing it unless you regularly order parts.
When I replaced the opamp the amp going into mute.What do you have on pins 6 and 7 when you have audio on pin 5?
Do you see any modulation on pin 7 when you have audio input?
Attaching square waves with and without audio.Is the square wave perfectly sharp? If you use audio instead of a sine wave, does the square wave look different?
Now it going into mute.You have modulation. If you have that at the input to the inductor and no audio on its output terminal, you likely have a broken connection on the inductor.