I don’t wanna post both amps in the same thread to make things confusing.
Anyway I have another 17k amp here that was installed in the system when they used amp scope and blew 2 of the amps up the 3rd amp has issues also .
So the 2nd amp in the system which I have in front of me the owner states that it has Terrible feedback . He stated when powering the amp down it sounds like a vacuum cleaner turning off . Also when the amp is powered up there is a loud hum through the subs .
He checked the rca shield ground in the head unit which are fine also installed another amp in the vehicle and it has no issues so it narrows it down to this amp .
Any ideas on what to check or where to start since everything is testing fine so far
Anyway I have another 17k amp here that was installed in the system when they used amp scope and blew 2 of the amps up the 3rd amp has issues also .
So the 2nd amp in the system which I have in front of me the owner states that it has Terrible feedback . He stated when powering the amp down it sounds like a vacuum cleaner turning off . Also when the amp is powered up there is a loud hum through the subs .
He checked the rca shield ground in the head unit which are fine also installed another amp in the vehicle and it has no issues so it narrows it down to this amp .
Any ideas on what to check or where to start since everything is testing fine so far
Thanks for not mixing threads.
Does it do this on the bench?
Does he know how to check the shield grounds properly?
Does it do this on the bench?
Does he know how to check the shield grounds properly?
Yes the amp does this on the bench as well .
I can hear the feedback through the subwoofer loudly
I can hear the feedback through the subwoofer loudly
Can you see the noise in the preamp signal leading to the output board?
Is the turn-on/off mute delay working as it should?
Is the turn-on/off mute delay working as it should?
I noticed I have 13.44 volts on the heatsink .
I also noticed 1 of the opamps had 3.3 volts on pin 1,2,3 (4556)
I also noticed 1 of the opamps had 3.3 volts on pin 1,2,3 (4556)
If you touch the heatsink with a grounded 2 ohm current limiting resistor, does the 13v drain away?
Is that section of that op-amp being used?
Can you see the noise in the preamp signal leading to the output board?
Is the turn-on/off mute delay working as it should?
Is that section of that op-amp being used?
Can you see the noise in the preamp signal leading to the output board?
Is the turn-on/off mute delay working as it should?
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I took all of the power supply spring clips off to see if that was the issue .
I noticed when I power the amp up now I’ll get 8 volts on the heatsink then it will drop back down to 0 volts after 20 secs . When I remove the remote wire the voltage will climb back up then drop to 0 .
I do not see the noise in the preamp signal .
The muting circuit is working correctly
Also IC202 is the one I’m getting voltage on pins1,2,3
I noticed when I power the amp up now I’ll get 8 volts on the heatsink then it will drop back down to 0 volts after 20 secs . When I remove the remote wire the voltage will climb back up then drop to 0 .
I do not see the noise in the preamp signal .
The muting circuit is working correctly
Also IC202 is the one I’m getting voltage on pins1,2,3
Attachments
If you touch the heatsink with a grounded 2 ohm current limiting resistor, does the 13v drain away?
Does the r-r oscillation stop immediately when you remove remote voltage?
Do you hear any noise when there is no r-r oscillation?
Do you hear any noise when there is no r-r oscillation?
Yes the rail to rail oscillation stops immediately after pulling the remote
I just noticed this not sure if it’s normal or not but I only get rail to rail oscillation on half of the outputs
I just noticed this not sure if it’s normal or not but I only get rail to rail oscillation on half of the outputs
It wouldn't hurt to include more than the least possible information.
Is this amp using two of these boards?
If not, what's the other board in the photo?
Is this amp using two of these boards?
If not, what's the other board in the photo?
Just for the record, the 4556 on the preamp section is used to mute the input signal and is un-muted by positive rail voltage fed to it through a few resistors in series.
Is one of the boards inoperable?
How do you define 'half'' for the outputs that don't have r-r oscillation? All of the FETs for one of these driver boards?
How do you define 'half'' for the outputs that don't have r-r oscillation? All of the FETs for one of these driver boards?