For amps that have a bridged output, you may see a small square or triangle wave on both output terminals. For amps with a negative speaker terminal connected to the secondary ground (this amp), if you see noise on the ground (negative speaker terminal), it means that you aren't using the right ground reference.
For 99%+ of the time, using the 12v supply ground for the scope ground is perfectly fine. When you're using very high sensitivity (low vertical amp settings), you have to use the correct reference. That's the secondary ground/the negative speaker terminal.
I wouldn't worry about the noise. It's common on most amps. Personally, I never worried about carrier frequency noise unless it caused a normally well focused trace to become significantly wider (2-3x wider)when the scope was set to 2ms and 5v/div.
If you're still concerned, go back with your original scope settings and look at the output with a load and the scope grounded to the negative speaker terminal.
For 99%+ of the time, using the 12v supply ground for the scope ground is perfectly fine. When you're using very high sensitivity (low vertical amp settings), you have to use the correct reference. That's the secondary ground/the negative speaker terminal.
I wouldn't worry about the noise. It's common on most amps. Personally, I never worried about carrier frequency noise unless it caused a normally well focused trace to become significantly wider (2-3x wider)when the scope was set to 2ms and 5v/div.
If you're still concerned, go back with your original scope settings and look at the output with a load and the scope grounded to the negative speaker terminal.
Ok I’m going to back track a lil on this amp .
Here is what I get on the gate leg for both high and low side fets .
Scope is set to 10us 2volts/div
This is with no signal
Do theses appear correct or what’s the next step ?
To me the square waves look very noisy on the scope .
Here is what I get on the gate leg for both high and low side fets .
Scope is set to 10us 2volts/div
This is with no signal
Do theses appear correct or what’s the next step ?
To me the square waves look very noisy on the scope .
Attachments
No the output is very distorted sounds like someone is farting through the test speaker as the audio plays
Should I drive a signal into the amp and check to see if I’m losing drive on the ic or do this with no signal ?
You stated that you were losing r-r oscillation. Do whatever you were doing when you were intermittently losing r-r.
Are you saying that you have no drive on the input pins (12 and 14) of the 2113 when the amp is producing distorted audio?
How to I determine if the driver ic itself is defective ?
Since I get no drive at all on pins 12,14
Or possibly if Q111 is defective
It’s a C3198 wondering if they use it for muting .
I tested the drive on pins 12,14 of the driver ic and get nothing with or without signal .
Since I get no drive at all on pins 12,14
Or possibly if Q111 is defective
It’s a C3198 wondering if they use it for muting .
I tested the drive on pins 12,14 of the driver ic and get nothing with or without signal .
I have no idea how this IC could drive the outputs to produce distorted audio with no drive.
Disable the driver IC ans see if you have drive to the IC. Lift pin 13 of the 2113 and connect it to pin 11 (12v above negative rail).
Does that give you drive pulses on the inputs of the 2113?
Disable the driver IC ans see if you have drive to the IC. Lift pin 13 of the 2113 and connect it to pin 11 (12v above negative rail).
Does that give you drive pulses on the inputs of the 2113?
If your meter has a frequency mode you could use it. That would be very accurate but I'm just looking for a ballpark.
What's the timebase setting that will show about 3 full cycles of the waveform.
What's the timebase setting that will show about 3 full cycles of the waveform.
Do you know what the scope settings were?
Was it locked on the signal to show just a few cycles?
Was it locked on the signal to show just a few cycles?