No sound from my AC15/Matchless clone's input

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No sound from my AC15/Matchless clone's input

Postby Muchless » Tue Feb 12, 2013 12:29 pm

Hi – and thanks in advance from a grateful newbie!
My home made AC15/Matchless clone has a problem – no sound coming out when I plug in a guitar.
The power amp seems to be OK because I can get sounds from my reverb unit via the effects loop. I can make these sounds quieter or louder using the volume knob but all the other pots (gain, bass, treble, mid) seem to have no effect. So am I right to think that the problem is somewhere after the tone stack, but before the volume pot? Trouble is, there doesn't seem to be much there! (???)
BTW just to be sure I’ve tried swapping round guitars, leads and valves (2x12AX7, 2xEL84, 1xGZ34) and it makes no difference. There is only one input jack.
Hopefully this has helped narrow down the source of the fault - but it would be brilliant if someone could give me some more clues about exactly where to look for the root cause, and what to test for.
Thanks!!!!
Muchless
 
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Re: No sound from my AC15/Matchless clone's input

Postby Gingertube » Tue Feb 12, 2013 11:53 pm

Can you post a schematic link - then we may be able to offer worthwhile advice.
Cheers,
Ian
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Re: No sound from my AC15/Matchless clone's input

Postby Muchless » Wed Feb 13, 2013 4:23 am

Thanks Gingertube!

Diagram here:

http://s1288.beta.photobucket.com/user/muchless/media/IMG_0001-Copy_zps59ae4149.jpg.html?sort=3&o=0#/user/muchless/media/IMG_0001-Copy_zps59ae4149.jpg.html?sort=3&o=0&_suid=136075017138902676922496641316

BTW my amp has separate volume and gain pots - but the diagram seems to show them combined(? unless I'm missing something). I may have done a mod and not updated the diagram - it was a long time ago... If need be I could always open up the amp and give you more details.

You can see where the FX loop is (after the .001 cap). As I said, I think that everything is OK past this point because when I plug in my reverb amp and tap the spring, it makes a BIG noise. The volume control works too (turning the reverb into a small noise), but the gain/bass/mid/treble have no effect.

Thanks!
Muchless
 
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Re: No sound from my AC15/Matchless clone's input

Postby Geek » Wed Feb 13, 2013 5:02 am

I can think of three things:

- Bum tube. I assume you rolled another pre tube?
- Bum pots or jacks. Got some Nu-Trol or contact cleaner?
- Crappy solder joint somewhere. Start wiggling wires.

Cheers!
-= Gregg =-
Fine wine comes in glass bottles, not plastic sacks. Therefore the finer electrons are also found in glass bottles.
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Re: No sound from my AC15/Matchless clone's input

Postby Muchless » Wed Feb 13, 2013 5:50 am

Thanks Geek!

I tried swapping the 12AX7s - no difference.

I'll give the pots a clean and a wiggle and check the soldering. Where would be the most likely place for a loose solder - near the tone stack?

To check the input jack should I just connect a guitar lead to the soldered connectors using croc clip leads? And for the FX loop jack can I just short out the "closed" connectors (ie with no FXs plugged in)?

Thanks again!!

PS Did you manage to find a separate Gain and Volume pot in the diagram? :/
Muchless
 
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