Need help trouble shooting

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MikeO
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Need help trouble shooting

Post by MikeO »

I have a homemade amp that I picked up in a trade years ago. It recently took a spill when my friend's dog knocked over the speaker cabinet that it was sitting on top of (she's an 85 pound pitbull who was terrified because some of my neighbors were lighting off fireworks). When I fire up the amp it still sounds great, but I am only getting a fraction of the volume I was getting before the amp took a spill. I swapped out each of the tubes with no luck, not really sure what else to do, and since it's a homemade amp I don't have a schematic or authorized service center that I can lean on.

Any ideas what could have happened from the fall it took that would reduce the volume dramatically, while otherwise sounding great? I figure, if nothing else, I now have that elusive holy grail of "cranked amp tone" at TV volume. :lol: With that being said, I'm afraid to use it for very long for fear some component will get fried.
Amps: 5150 (w/bias mod), 5150 II, PRS MT-15, FJA PV XXX, Framus Dragon, FJA PV Penta, PV Rockmaster-->Marshall 9100, PV Ultra 120
Cabs: 3 Marshall 1960B, Laney GH412, Avatar 2x15, PV XXX 4x12, Bogner OS 2x12.
Deville
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Re: Need help trouble shooting

Post by Deville »

I just dealt with the same issue on my Carvin, and after trying several things it turned out to be an open anode resistor in one of the preamp tubes. Fortunately for me i had schematics, so I knew what voltages to look for. Did you try swapping all tubes or just go one by one cause it could be more than one since it fell? Otherwise I'd look for obvious damage to the pcb itself, concentrating on the tube sockets to start with. Good luck, I know how frustrating this is...
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Zozobra
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Re: Need help trouble shooting

Post by Zozobra »

How complicated is the amp? Can you post up some pictures?
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MikeO
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Re: Need help trouble shooting

Post by MikeO »

Zozobra wrote:How complicated is the amp? Can you post up some pictures?


Sorry, just saw that you had replied to this thread.

I need to get the chassis out of the headshell to get a picture of the guts, I should get a chance to do so in the next couple of days. Will post as soon as I do.
Amps: 5150 (w/bias mod), 5150 II, PRS MT-15, FJA PV XXX, Framus Dragon, FJA PV Penta, PV Rockmaster-->Marshall 9100, PV Ultra 120
Cabs: 3 Marshall 1960B, Laney GH412, Avatar 2x15, PV XXX 4x12, Bogner OS 2x12.
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ajaxlepinski
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Re: Need help trouble shooting

Post by ajaxlepinski »

My money is on a loose wire/solder joint or, tube socket clip came loose or broke.
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Deville
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Re: Need help trouble shooting

Post by Deville »

Kinda curious if what this amps pcb looks like...
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