Big Muff burning thru batteries

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charge
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Big Muff burning thru batteries

Post by charge » Sun Dec 17, 2017 3:26 pm

Hey all, I have an almost mint Op Amp Big Muff that eats batteries when the input cable is disconnected, which is probably why it's almost in mint shape. Is there a wire connected to i.e. the wrong lug? Thanks!

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devnulljp
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Re: Big Muff burning thru batteries

Post by devnulljp » Wed Dec 20, 2017 9:42 am

I can't see anything obviously wrong with the wiring, but I'd ask one of the resident builders to look at it. Might have a short somewhere ... does the battery get warm?
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Dr Tony Balls
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Re: Big Muff burning thru batteries

Post by Dr Tony Balls » Wed Dec 20, 2017 3:13 pm

Its not wired *correct* but I dont see that its wired in a problematic way. It looks like the battery ground is wired to the board and the board ground wired to be switched at the jack. Normally the board ground would be hard wired to ground and only the battery ground would be switched at the jack. Its unconventional, but as long as its still switched it should be fine. Could be that the board has a second grounding path, or maybe the input jack is shorted... do you have a multimeter to check if theres connectivity between the battery negative and the case?

pic from Kit's site for reference. compare the wiring of the input jack and battery:

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pagan
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Re: Big Muff burning thru batteries

Post by pagan » Wed Dec 20, 2017 3:27 pm

I don’t think the input jack is wired to connect/disconnect the ground at the board. It looks like there’s only two wires from the input — from the tip and one sleeve connection. There’s a similar one here: https://www.tonehome.de/electro-harmonix/big-muff-π/
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pagan
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Re: Big Muff burning thru batteries

Post by pagan » Thu Dec 21, 2017 3:52 pm

If you don’t want to mod it, you can just use a power plug as a switch. Plugging into the power jack disconnects the battery.
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devnulljp
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Re: Big Muff burning thru batteries

Post by devnulljp » Thu Dec 21, 2017 8:22 pm

pagan wrote:If you don’t want to mod it, you can just use a power plug as a switch. Plugging into the power jack disconnects the battery.
Looks to me like it's already been modded -- the wiring is tidier than usual EHX.
Dear Bongo, No.
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charge
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Re: Big Muff burning thru batteries

Post by charge » Thu Dec 21, 2017 10:20 pm

Cool, thank you all for taking a look at this mystery machine.

I’ll send it off to one of the fantastic builders who frequent this forum after I get back home from my travels.
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