Audio only on left side

IntarsiaGuy2 · 1217

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Offline IntarsiaGuy2

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on: May 28, 2021, 07:13:31 AM
Hello, just finished a crack build and have audio only coming out the left side.

Below is what I have done:
- Inspected all solder joints.  Fixed any that looked at all dubious.  Having said that, I have only been soldering a short time and so my inspection skills are probably not the best.
- Went back and reviewed each step.  Cap that goes from 6 to 7 was backwards.  Fixed that.  Did not find any other errors.  Could this have caused damage?
- Went through all resister and voltage checks successfully.
- Tried it and only get output from the left side.  NOTE: when I swap RCA cables, I still only get audio from the left.  This eliminates the RCA connectors and cables.
- tried a different pair of headphones with no difference

Would appreciate advice on specific things to look for since my general inspection did not resolve the issue.

Thanks, Scott



Offline IntarsiaGuy2

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Reply #1 on: May 28, 2021, 07:17:32 AM
Also just measured the 2 resisters installed on the headphone jack and they both measure correctly.



Offline IntarsiaGuy2

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Reply #2 on: May 28, 2021, 07:25:27 AM
Just realized my "it's not the RCA jack" logic is faulty.  But resoldering did not improve things.



Offline Toobuzz

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Reply #3 on: May 28, 2021, 07:43:02 AM
Hi there. If I were you I would turn the volume pot half way up and connect your RCAs, flip it over just like you were going to do your voltage checks and power it on.  Please be very careful as you were when doing the voltage checks.

If you play music (preferably a 1K test tone) you should be able to see voltages on the wires connected to the center pins of the RCA jacks. With your black lead secured to the ground nut, use your red lead to test AC voltage on the pins of each RCA and then again on the lugs both entering and exiting the volume pot.

This should at least rule out your source, the RCAs and the volume pot including your wiring in those areas.  Definitely stop this type of troubleshooting at the output of the volume pot. You don’t want to be poking your test lead around any high voltage sections.
« Last Edit: May 28, 2021, 08:05:08 AM by Toobuzz »



Offline IntarsiaGuy2

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Reply #4 on: May 28, 2021, 08:06:19 AM
Thanks for the response.  I played music, not a tone.
Both RCA jacks measured in the .3 to .5 volt range - changing (I assume) as the music was changing.

Bottom row of the volume attenuator, starting closest to the side was
.3 to .5
1.15
0

Top:
.3 to .5
1.2
0




Offline Paul Birkeland

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Reply #5 on: May 28, 2021, 08:20:34 AM
The big problem here is that you didn't perform the voltage check when you finished building your amplifier.  The backwards cap would've thrown all your voltages off and you would've determined that your amp wasn't working at that time.  Plugging in your headphones to try to listen to the amp with the backwards cap could absolutely have damaged your headphones.

The first step to take is to plug your headphones into something else with a headphone jack to be sure they are damaged.

The second step to take is to perform the DC voltage checks to see if your amplifier is working properly.  If any voltages are off, post your voltages on terminals 1-10 here and we can let you know what to do next.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man