Connected a 1k resistor between the screw and primary ground .
I get no change still get the square wave and also get the square wave on the buss bar
I get no change still get the square wave and also get the square wave on the buss bar
Ground the heatsink through your 2 ohm limiting resistor. Do you see an increase in current draw from the 12v supply?
Confirm if the frequency that you are seeing on the heatsink is at the power supply frequency or at the audio section frequency. Perhaps that can point you in a direction of what section in the amp to look at?
I know that you said it was at the audio switching frequency, just confirm it again.
I know that you said it was at the audio switching frequency, just confirm it again.
I'd suggest that you leave the scope connected to the heatsink with everything clamped down. Then start removing clamps, one at a time, and lift the semiconductors to see if the noise decreases for any component.
I don't think this is the main issue but it's hard to say definitively.
We also need to determine why the problem occurs with the head unit but not with your signal generator.
What happens if you jump the RCA shields to the primary ground with a jumper wire?
I don't think this is the main issue but it's hard to say definitively.
We also need to determine why the problem occurs with the head unit but not with your signal generator.
What happens if you jump the RCA shields to the primary ground with a jumper wire?
If I jump the rca shield ground to primary ground there is no change .
I removed the board from the heatsink to rule out anything that may be causing the issue .
Amp still has the square wave at the rca ground shield and test speaker still
Has a loud hum
I removed the board from the heatsink to rule out anything that may be causing the issue .
Amp still has the square wave at the rca ground shield and test speaker still
Has a loud hum
"If I jump the rca shield ground to primary ground there is no change "
Do you mean that there is still -0.5v and the square wave with the jumper in place?
If you leave the jumper on the RCA shields and plug in the head unit, do you still have the noise?
What if you try your signal generator with the RCA to primary ground jumper? Do you get the noise?
Do you mean that there is still -0.5v and the square wave with the jumper in place?
If you leave the jumper on the RCA shields and plug in the head unit, do you still have the noise?
What if you try your signal generator with the RCA to primary ground jumper? Do you get the noise?
Yes I still get the -0.5 volts and the square wave on the rca shield ground with jumper in place
If I leave the jumper in place and plug the head I it in the noise gets worse .
Even with the signal generator hooked up and I leave the jumper in place i still get the noise
If I leave the jumper in place and plug the head I it in the noise gets worse .
Even with the signal generator hooked up and I leave the jumper in place i still get the noise
The reason that you probably don't get the noise with the generator is because there is no shield ground.
Do you have a GLI to insert between the head unit and the amp?
If so, remove the jumper and try the head unit with the GLI in place.
Can you use your phone/MP3 player (operating purely from batteries) to see if that has noise?
Do you have a GLI to insert between the head unit and the amp?
If so, remove the jumper and try the head unit with the GLI in place.
Can you use your phone/MP3 player (operating purely from batteries) to see if that has noise?
Not sure what you mean by GLI ?
I have to get a cord for my phone so I can hook up to the amp .
With no rcas plugged into the amp I get the same noise on the speaker terminal .
Wondering if this noise would cause the amp to play then protect then play then protect .
The guy stated that was the problem the amp would protect whenever it wants to it will play fine for a day then the next day it will play and Go into protection over and over .
He never said anything about noise in the system so I’m wondering if the amp doesn’t like something on my test bench and the problem with the noise is on my test bench and not the vehicle
I have to get a cord for my phone so I can hook up to the amp .
With no rcas plugged into the amp I get the same noise on the speaker terminal .
Wondering if this noise would cause the amp to play then protect then play then protect .
The guy stated that was the problem the amp would protect whenever it wants to it will play fine for a day then the next day it will play and Go into protection over and over .
He never said anything about noise in the system so I’m wondering if the amp doesn’t like something on my test bench and the problem with the noise is on my test bench and not the vehicle
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Ground loop isolator.
Lets differentiate. 'Hum' is the low frequency sound you hear through the speaker. "Noise" is the high frequency leakage that you can only see with the scope. Copy and paste your last post and insert either hum or noise where applicable.
Lets differentiate. 'Hum' is the low frequency sound you hear through the speaker. "Noise" is the high frequency leakage that you can only see with the scope. Copy and paste your last post and insert either hum or noise where applicable.
Ok I will reword it .
I can see the noise on the rca shield grounds of the amp .
I also see the same noise on both positive and negative speaker terminals of the amp .
Wondering could this cause the amp to protect intermittently or would the problem with it protecting be a different issue ?
I can see the noise on the rca shield grounds of the amp .
I also see the same noise on both positive and negative speaker terminals of the amp .
Wondering could this cause the amp to protect intermittently or would the problem with it protecting be a different issue ?
Do you see the 'noise' if you use the secondary ground as the scope ground (connect the small ground wire that connects to the probe hand piece to the secondary ground) and disconnect the wire that connects the scope to the 12v power supply?
I don't think this is causing the hum problem. There is a hum problem as well, correct?
I don't think this is causing the hum problem. There is a hum problem as well, correct?
Still see the noise when I use the secondary center tap as ground reference for the scope
And I talked with the guy today about the amp .
He said the hum is present in the vehicle as well .
He stated the original problem with the amp was the power supply failed he sent the amp in for repair and it came back and the hum was present then
And I talked with the guy today about the amp .
He said the hum is present in the vehicle as well .
He stated the original problem with the amp was the power supply failed he sent the amp in for repair and it came back and the hum was present then
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Does this have anything to do with a previous thread of mine where it wasn't oscillating and after driving a signal the DC went away?