Lone king low output

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Grazza

Active member
Just finished a lone king, arrogantly thought I'd be sweet, it's such a basic circuit!

However, when on output is lower than it should be, even when all the way up. It does sound like it should though, just a lot quieter.

Pulled it out of the box and tried the audio probe and I pretty much get static on every component. I'm not great at trouble shooting at the best of times, this has got me stumped.
 

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Hey. All of the parts that I can see look fine. I can't check the electrolytic capacitors or the pots but maybe doulbe check you have the right values.

I would suggest re-heating all of the solder points. There might be a solder bridge or a bad connection.

And also check the op amp voltage. It should be roughly the values below. If not that is a big clue to where the issue might be.

1 - 4.5v
2 - 4.5v
3- 4.5v
4 - 0.0V
5 - 4.5v
6 - 4.5v
7 - 4.5v
8 - 9v
 
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Grazza said:
Just finished a lone king, arrogantly thought I'd be sweet, it's such a basic circuit!

However, when on output is lower than it should be, even when all the way up. It does sound like it should though, just a lot quieter.

Pulled it out of the box and tried the audio probe and I pretty much get static on every component. I'm not great at trouble shooting at the best of times, this has got me stumped.
Click to expand...
If you get a chance, can you post a pic of the entire thing. Jacks, switch and all. And the underside too if possible.
 
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Schematic-LoneKing.jpg
 
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If all the components check out ok you might have a broken trace that can’t be seen. Not common but it did happen to me twice. The audio probe or checking for continuity with a multimeter will sort that out.
 
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Now that I have the schematic I'll follow it through, I actually have 2 builds like this where they work and sound as they should but they are really quiet. Haven't even started trouble shooting the other one yet. At least this one is a basic circuit. I noticed there where a handful of places where there seemed to be the correct volume, so there is hope. Is it ever a bad pot? I don't really know how to test them in the circuit.
 
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Checking voltage can be a quick way to indenting where a pro might be.

Also audio probing helps. Where are the places with correct volume and where does that stop?

It can be a bad pot. If you have an ohm symbol on the multimeter l. Use that to measure resistance over pins 1 and 2. Should go in and down when you turn it. Works better with no power
 
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Ok, finally had a chance to to some probing on this one, I have a stupidly busy life at the moment, not a lot of time for hobbies. Audio is as it should be on this one until I get to C3. Which is a 220uF electrolytic. For some naive reason I thought they there would be no signal through these capacitors as they are electrolytics, but they are part of the signal chain aren't they? This is where my problems begin isn't it? Should I remove c3? and probably C4, I'm assuming if one is bad, then the other is too (I will do one at a time though)?
 
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Your voltages are fine, I would last resort replace C3. I've had duds from tayda etc. You should have audio thru R3, +side of C3, to R10/tone pot lug 1 junction following the schematic. Try replacing C3, or at least reflowing the pads. Can't see in the pics of the solder side, but your soldering looks fine that I can see. Scrub your board though!
 
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Ah, C3/C4 are supposed to be 220nF (0.22uF) tantalums, not 220uF electrolytics.
(I had to double check when you said these chonky bois were part of the audio path!)

I imagine 220nF film capacitors would work just fine there too if you can get them into the space.
(Leads might be closer together than the board wants, maybe you can bend 'em)
 
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Crap, I din't realise there had been more posts on this thread. In the meantime I have ordered more 220uf electrolytics and replaced them with no positive effect. Is that because I'm using electrolytics? There is some volume and the effect sounds like it should but unity is at full volume and drive. If I replace the electrolytics with Tantalums do you think it will work?
 
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Yeah just looked at the build docs again, not sure how i went so wrong, 220nF tantalums, thanks for the heads up, very embarrassing. May as well order some and try that out, pretty sure it has to fix it.
 
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