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Re: Troubleshooting from a schematic
To: CRTech <crtech@crtech.org>
Subject: Re: Troubleshooting from a schematic
From: John Stortz <ka4flx@gmail.com>
Date: Sun, 7 Jan 2018 23:45:17 -0500
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In-reply-to: <0MKaY5-1eVkHt1tPb-0024c4@mrelay.perfora.net>
References: <62CE64C1-DAF3-4FC6-987E-AA48F6388FAC@am91.org> <0MKaY5-1eVkHt1tPb-0024c4@mrelay.perfora.net>
Tubes? Transistors? ICs?

In any case, if the noise doesn't change with any controls, the problem is probably after the controls

John S.

Plow Deep while the sluggards sleep.
*~Franklin~
  


On Thu, Jan 4, 2018 at 10:56 AM, Wiely Boswell <wiely@faithradio.org> wrote:
Is it a class D amp ?  They would seem to be able to do such a thing but I
have no experience troubleshooting them.
Interesting topic,
Wiely

-----Original Message-----
From: Dan Harder [mailto:dan@am91.org]
Sent: Tuesday, January 02, 2018 8:13 AM
To: CRTech
Subject: [CRTech] Troubleshooting from a schematic

Hey all,

My son inherited an old Crate brand instrument amp from his uncle last
summer. It worked well for about 3 months, and 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,

The noise is constant and does not vary with any knob adjustment.

Would anyone here mind a look at the drawings and venture a guess as to what
component(s) might be guilty?

Private message me if you're interested.

Dan Harder
dan@am91.org



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References: Troubleshooting from a schematic
(Dan Harder <dan@am91.org>, 2 Jan 2018 14:13:01 -0000)
RE: Troubleshooting from a schematic
("Wiely Boswell" <wiely@faithradio.org>, 4 Jan 2018 15:55:37 -0000)
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