Yes, it does become greater, I checked the centre pin of each transistor. I had no problem pushing the voltage up to 40V+
What is the resistance between the emitter leg of any output transistor and the positive speaker terminal?
Previously, you stated that the output was distorted and there was about 1v across the speaker terminals. Was the 1v there with a speaker connected or did it drop to 0v?
Was it distorted but very loud?
Did you try it without the limiter, confirming that there was 12v+ across the B+ and ground terminals?
Was it distorted but very loud?
Did you try it without the limiter, confirming that there was 12v+ across the B+ and ground terminals?
Hi Perry, thank you for your help this far.
To answer your question I tried your suggestion.
The distortion is fairly loud, as in louder than the actual music playing. (however in real world application I might not hear it installed) I cautiously powered the amp up tonight with a fuse instead of the limiter, (voltage was 12V at the amplifier power terminals) and the output is the same. Without music playing but source hooked up, I would have to describe the sound as "white noise"
I made a sample video of the output with source playing.
http://www.youtube.com/watch?v=sQ1SH4J5SaI
It should be noted, that the DC output starts around 1.2VDC but slowly drops. for example, tonight it had dropped to about .75 before I disconnected the power supply.
To answer your question I tried your suggestion.
The distortion is fairly loud, as in louder than the actual music playing. (however in real world application I might not hear it installed) I cautiously powered the amp up tonight with a fuse instead of the limiter, (voltage was 12V at the amplifier power terminals) and the output is the same. Without music playing but source hooked up, I would have to describe the sound as "white noise"
I made a sample video of the output with source playing.
http://www.youtube.com/watch?v=sQ1SH4J5SaI
It should be noted, that the DC output starts around 1.2VDC but slowly drops. for example, tonight it had dropped to about .75 before I disconnected the power supply.
I don't understand. How is installing it when it's in the vehicle going to make the audio less distorted/noisy if the noise is louder than the music?
What are you using for a signal source?
Where was the black probe when you measured the DC voltage on the speaker terminals?
What are you using for a signal source?
Where was the black probe when you measured the DC voltage on the speaker terminals?
My apologies, it was quite early in the morning when I wrote that. What I said does not make sense.
When I test for DC voltage I am placing the black probe on the negative speaker terminal.
Is this incorrect?
I am using my Ipod for my source.
When I test for DC voltage I am placing the black probe on the negative speaker terminal.
Is this incorrect?
I am using my Ipod for my source.
Using the negative speaker terminal was correct.
??>> I don't understand. How is installing it when it's in the vehicle going to make the audio less distorted/noisy if the noise is louder than the music?
??>> I don't understand. How is installing it when it's in the vehicle going to make the audio less distorted/noisy if the noise is louder than the music?
Hi Perry,
I am curious now if maybe I should test with a different speaker. The distortion is louder than the music, but maybe the speaker is defective itself. I'm not a complete noob, I swear, just throwing ideas out there is all.
As for the white noise, I am using a full range speaker, if it were running to my subs, in the trunk I might not be able to hear it.
I am curious now if maybe I should test with a different speaker. The distortion is louder than the music, but maybe the speaker is defective itself. I'm not a complete noob, I swear, just throwing ideas out there is all.
As for the white noise, I am using a full range speaker, if it were running to my subs, in the trunk I might not be able to hear it.
With the black probe on the amplifier's main ground terminal and the red probe on the input RCA shield, what is the DC voltage?
If it's essentially 0v, connect a jumper from the RCA shield to the amp's main ground. Does that make a difference?
Is there less noise when there is nothing plugged into the RCA jacks?
If it's essentially 0v, connect a jumper from the RCA shield to the amp's main ground. Does that make a difference?
Is there less noise when there is nothing plugged into the RCA jacks?
I tested both ways, the white noise is the same volume with or with out source connected.
I only read about 1.5mV between the RCA shield and the negative terminal.
I jumped the shield to the negative terminal block and the sound is the same as it is without the jumper.
To rule out the speaker, I changed it, and the same distorted sound persists.
I only read about 1.5mV between the RCA shield and the negative terminal.
I jumped the shield to the negative terminal block and the sound is the same as it is without the jumper.
To rule out the speaker, I changed it, and the same distorted sound persists.
Any other ideas? Could this be in the input section?
On a side note, R166 is discolored but tests ok at 100ohm.
On a side note, R166 is discolored but tests ok at 100ohm.
Oh, that sucks.
Do I need to spend a lot on a scope? Or will a used one with limited features work?
Do I need to spend a lot on a scope? Or will a used one with limited features work?
Do you intend to continue doing this type of work?
If not, you should pay someone to repair it. If you are going to do more repairs and want to buy a scope, you'll probably have to spend about $150-200 on a scope.
If not, you should pay someone to repair it. If you are going to do more repairs and want to buy a scope, you'll probably have to spend about $150-200 on a scope.
I am sure that this will not be the last amplifier I work on... If I can buy broken and repair for less than new, that Is what I choose to do... Might only be one a year. But I prefer to do as much stuff as possible on my own.. from car repairs to electronic repairs etc.
If you decide to purchase a used scope, post a link to it to get some opinions as to whether it's a good choice.
I have this amp and the owner here right now... where would you like me to start checking for this distortion Perry?
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