Author Topic: Sunn Concert Bass  (Read 1668 times)

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Offline MammothVolume

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Sunn Concert Bass
« on: September 08, 2011, 09:25:50 am »
Alright, I've got a silver-era Sunn Concert bass that someone sent to me in not-working order. First thing I noticed, someone goofed with the speaker outs, added a speakon out in place of the master out. The original jack that was paralleled is still there. I want to put it back to stock, before I start trouble shooting, just could have been a botched job, before I start metering and all of that fun stuff. So, my question to you'se guys, anyone have a picture of what the original output scheme looked like? How the main jack was wired? Was it a stereo jack? Anyone have the service manual? I've drawn a blank on all my searches. Just lemme know!

Offline loudthud

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Re: Sunn Concert Bass
« Reply #1 on: September 08, 2011, 10:09:33 am »
Look at this thread:

http://sunn.ampage.org/sdp/index.php/topic,4515.0.html

There are some schematics posted for one of the early versions of the Concert Bass.

Offline MammothVolume

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Re: Sunn Concert Bass
« Reply #2 on: September 08, 2011, 12:41:22 pm »
UPDATE!

I have guitar signal, strong guitar signal through the amp. Before it was just a bzzzzzzzzzzzzzzzzzzzzzzzzzzz. Now it's guitar signal that'll outdo the buzz, but the buzz is very present. I've been trying to balance it with the trim pot on the poweramp board, it does its job, but the buzz is very present. I suspect some of the questionable solder joints may be the culprit. Just thought I'd update you guys. Thanks for the link, loudthud!

Offline MammothVolume

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Re: Sunn Concert Bass
« Reply #3 on: September 08, 2011, 01:39:31 pm »
All solder joints hit, buzz still there.

There's a questionable cap. a 220uF/63V cap in an area with two 1000MFD/50V caps, where the 220uF is, it's obviously a hack job, someone clipped the leads of the old cap and soldered it in place. I'm assuming, and according to the schematic, there should be three of those 1000MFD caps in a pretty tight space. Am I wrong to think this?

That could be the cause of the buzz?

Offline MammothVolume

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Re: Sunn Concert Bass
« Reply #4 on: September 09, 2011, 04:23:53 pm »
Wasn't the cap. Thanks for the links to the schematic/layouts. I'm pretty much at a loss. I chopsticked everything, pulled wires. etc.