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Old 19th January 2013, 04:00 PM   #1
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Question SWR Workingman's Bass

This was a thrift store find and the input jacks were in bad shape. Played well for all of the battle scars until .."pop" and a series of flutters went throught the speaker. Now,I get a hum and but no signal from the inputs. I am a novice but am not squeemish when it comes to this stuff..Any ideas????spare parts resources? personal experience? Thanks
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Old 19th January 2013, 05:47 PM   #2
Enzo is offline Enzo  United States
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Location: Lansing, Michigan
What model is the amp, SWR made a number of Workingman amps, just like General Motors made several Chevrolet model?

Now, more specifics. When you say hum, is it a LOUD hum, or just annoying hum, or mere bacjground hum? If LOUD hum, look at the speaker cone. Does it move one direction and stay there? Or does it remain more or less at rest position. If it moves and stays, TURN IT OFF and do not connect a speaqker until we know it no longer makes DC voltage. DC voltage is what makes the speaker stick in one position, and it will destroy th speaker if left there.

If the speaker/DC-voltage thing is not the issue, then you may have lost a main filter cap. Cap could have failed or the solder to it may have cracked. It is also possible the low voltage supplies lost a filter cap, or for that matter even one went away completely.

So we ought to check all the power supplies. The power amp will have some voltage or other, both polarities, and it matters which model, it could be anywhere from 25v to 80v. The preamp runs on +15 and -15, so find those and see that they are up to voltage. All four of those need to be free of ripple.

Once we know what amp it is we can also try some thing to narrow it down, like using the FX loop jacks.
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