New Build / Missing sound in right channel [solved]

blackraen · 1494

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Offline blackraen

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on: April 20, 2015, 09:04:41 PM
Hello everyone.

Recently finished building my first Crack kit and was surprised going through my resistance and voltage checks to see everything check out great my first time through.

After completing the TRS check I went to do my first listening test and found that I'm missing sound in the right channel.  I tested all the associated equipment inline to verify that everything else was good and at this point I'm 100% confident that it is something internal to the crack system (2 different sets of RCAs, switching inputs resulting in left output channel only still).

Got too late to dig too deep but my planning a pass through to perform a resolder on everything in the right channel path from input to output, but was wondering if there were any other first stage 'one-channel-missing' troubleshooting steps I should focus on to maximize my debugging time.

One other small thing I noticed was a very slight amount of microphony on the left channel specific to tapping the top plate.  I did not notice any microphony during associated with music playback, but I was a little distracted.  The left channel sounded great otherwise.

Sorry about not pictures, will grab photos if the resolder doesn't help tomorrow.
« Last Edit: April 21, 2015, 12:08:52 PM by blackraen »



Offline borism

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Reply #1 on: April 21, 2015, 05:21:41 AM
If all resistance and voltage checks were fine, I would wonder about the contacts at the headphone jack. However, I am sure the pros will have much clearer suggestions.

Boris


Offline Paul Birkeland

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Reply #2 on: April 21, 2015, 07:05:13 AM
A very common source of a problem like this would be too much solder on the center cup of the right RCA jack, which would cause a short at the input of the right channel.  (Will appear in the resistance checks, however)

After you pop up some photos, I can suggest some places to temporarily add in little pieces of wire to send some signal front the left channel into the right channel, to isolate where the signal isn't making it through.

-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline blackraen

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Reply #3 on: April 21, 2015, 12:08:28 PM
Finally got to get back in the shop and sat down to take a look and while I was doing a visual inspection along the right channel path I found the problem -- bad job soldering the cap on 7. 

I  messed up earlier when I brought the 5w resistors to the upper terminals and the socket wires to the lower terminals so when it came time to attach the caps I had a bit of a scramble and tried to just wiggle them in there rather than move the wires/resistors and didn't get a good flow to the cap's wires.

I suspect that my resistance and voltage checks worked out because I was applying enough pressure with the probe to make the connection, either that or I managed to break the weak connection when I was probing. 

But it's working great now.  What I deserve for trying to solder tired.