Course attenuator Issue

Souter · 181

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Offline Souter

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on: February 26, 2024, 12:11:48 PM
I’ve just finished my build and passed all the resistance, voltage and bias checks.

When playing audio the left channel completely cuts off when selecting the -16db, -9db & 0db settings on the course attenuator.

I’ve had a good look but nothing obvious is jumping out at me.

Any suggestions would be most appreciated.



Offline Paul Birkeland

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Reply #1 on: February 26, 2024, 02:31:22 PM
The resistor between -18dB and -27dB probably isn't soldered on one end.  I'm guessing the level of the left channel and right channel doesn't really match well above that as well?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Souter

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Reply #2 on: February 27, 2024, 12:45:01 AM
Hi Paul, thanks for your reply.

The level balance sounds fine above -18.
I've attached a picture of the attenuator, I noticed that the switch wasn't reaching some of the connector clips but I have rectified that now.
Does the soldering look okay?
I've just noticed a hairline crack on the top of the blue area which is a bit concerning!



Offline Paul Birkeland

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Reply #3 on: February 27, 2024, 04:37:45 AM
That switch needs to be removed and replaced.  For whatever reason, you have some bent contacts on one side that are causing your problem.  It looks like something smooshed into them and mangled them a bit. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Souter

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Reply #4 on: February 27, 2024, 05:47:30 AM
Thanks Paul, I'll order some new parts.