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RE: Troubleshooting from a schematic
To: CRTech <crtech@crtech.org>
Subject: RE: Troubleshooting from a schematic
From: "Allard, Mark G" <MGAllard@unwsp.edu>
Date: Tue, 2 Jan 2018 22:43:46 +0000
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Thread-topic: [CRTech] Troubleshooting from a schematic

Under the topic of divide and concur;

Sometimes these amps have TRS ¼ “ jacks to insert special effects or a line out for recording, etc.

Maybe try monitoring at those points to see if the noise is pre or post that point.

Mark A


From: Sherrod Munday [mailto:smunday@ieee.org]
Sent: Tuesday, January 02, 2018 12:39
To: CRTech <crtech@crtech.org>
Subject: Re: [CRTech] Troubleshooting from a schematic


On Jan 2, 2018 9:13 AM, "Dan Harder" <dan@am91.org> wrote:

... now is a white noise generator and only the smallest amount of audio from any of the 3 inputs leaks thru.

I have schematics, but the PC board is not marked at all, and I’ve spent several hours trying to determine the cause. I have access to a fluke scope-meter,
Would anyone here mind a look at the drawings and venture a guess as to what component(s) might be guilty?


Have you tried poking around with an inductive audio amplifier? 


I'd start at the output and work your way back through the devices/components on the PCB looking for where the white noise starts and the good audio stops.



References: Troubleshooting from a schematic
(Dan Harder <dan@am91.org>, 2 Jan 2018 14:13:01 -0000)
Re: Troubleshooting from a schematic
(Sherrod Munday <smunday@ieee.org>, 2 Jan 2018 18:39:27 -0000)
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