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Topic: BL 712 shorting out??? |
Pete Burak
From:
Portland, OR USA
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Posted 12 Apr 2013 8:50 am |
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On my Zum S12U there is what appears to be a BL 712 pickup.
My right palm inadvertently made the 12th string touch the pole piece, and the pickup went momentarily silent.
I also have a tick/click when I just touch the side of the neck with with my finger.
I thought the pickup needed to be grounded (only one black and one white wire coming from the pickup), so I ran a jumper from the sleeve to the changer, and the pickup output goes to zero.
I discovered that if I push any string down so it touches a pole piece on the left row, the pickup goes dead... if I push any string down so it touches the pole piece in the right row(without touching the left row pole piece), I still have normal output.
Is this pickup shot?
Any ideas before I unstring this steel to look at the underside of this pickup? |
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Stephen Cowell
From:
Round Rock, Texas, USA
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Posted 12 Apr 2013 7:42 pm
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What this means is that one winding has become shorted to the pole piece armature. This would normally mean a re-wind or replacement... or live with it, your choice.
If you reverse the wiring to the pickup you'll change the problem... instead of cutting out, it'll hum, depending on where the short is. Perhaps preferable?
_________________
Too much junk to list... always getting more. |
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Pete Burak
From:
Portland, OR USA
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Posted 13 Apr 2013 6:33 am
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Thanks, Stephen.
It doesn't sound bad under normal playing conditions, but from your diagnosis, seems like I need to get a new pickup in there.
I am thinking of sticking a 1\4" slice of the soft side of some sticky-back Velcro just in front of the string-12 pole piece, to eliminate the possibility of contact, just as a quick fix.
Thx,
Pete
[update]
I just put a very small square of black electrical tape over the offending pole piece, and it stops the pickup from shorting out while playing.
I did notice that when I touch any pole piece in that row with my fingerpick, there is alot of noise. Touching any pole piece in the other row is just a small click (normal sounding).
I will de-string next time I get enough coffee in me and try to take a look in there to see if I can clear the short, and/or maybe send it off to Lawrence for repair, or just buy/install a differnt pickup in there. |
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