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No. The power rails.Originally posted by tonebells View PostExperience is something you get, just after you really needed it.Comment
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2.2K across C21 makes the voltage on the output take much longer to drop.
TonyComment
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If you are going to test that way you're doing it wrong. The 2.2k ( guess at value) purpose is to mute the amp while you turn the power on. With the power still on you disconnect the 2.2k and observe the voltage on the output. The point is you are now un muting at a point in time when the power supplies are know to be stable, so if you still see the 6.5V bounce you can eliminate power supplies as a factor.Originally posted by tonebells View PostExperience is something you get, just after you really needed it.Comment
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The .5 volt on the output drops as soon as the amp unmutes with no bounce.
TonyComment
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Ah ha! That tells us the power supplies are causing the bounce. So, you need to monitor the power rails to this channel with your scope at power. Your PC scope, having digital storage is better for this.Originally posted by tonebells View PostExperience is something you get, just after you really needed it.Comment
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One channel on the PC scope read voltage wrong by about 5 volts but we can give it a try.
Well today it's working.
TonyLast edited by tonebells; 04-24-2018, 01:11 AM.Comment
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I have the PC scope setup.
TonyComment
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With the +/-36 volts unhooked from the driver board I still get the +5 volts and hum on the speaker output.
TonyComment
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I went with my gut and pulled Q9. It test low gain and high leakage. I will most likely not have it back together until tomorrow.
TonyComment
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I got it back together and tested for operation. Powered down for thirty minutes and powered up without DC on the outputs. Will try with speakers next.
TonyComment
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No hum and no dc on the outputs
. Thanks for the help.
TonyComment
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Well, not much help in this case - you figured it by yourselfOriginally posted by tonebells View PostNo hum and no dc on the outputs. Thanks for the help.
Tony
Experience is something you get, just after you really needed it.Comment
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It was a great help. I was down to just staring at the schematic. Q10 and Q14 had been replaced before I got the receiver so Q9 and Q13 had been on my mind from the start. Thanks againOriginally posted by nickb View PostWell, not much help in this case - you figured it by yourself
TonyComment
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