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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.

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,

-----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

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

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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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