[pianotech] Build a Zapper

Delwin D Fandrich del at fandrichpiano.com
Mon Mar 30 16:45:41 PDT 2009


Before this thing becomes so technologically advanced it can't be put together
without a built-in microcomputer chip let me remind folks that these things are
supposed to be simple.
 
Mine was built using a 6.3 vac filament transformer. Back in the day they were
readily available just about anywhere really cheap. Now that vacuum tubes are no
longer in common use it might be necessary to ask somebody at Radio Shack.
Personally, I'd not go any higher than this in voltage. Remember these things
are a short-circuit sort of device and using a lower voltage tends to hold the
current down some. I put a simple push switch in so I could better time the
application of current. An argument could be made that this is not strictly
necessary but it also keeps the thing from shorting out when you lay the probe
across the end of your screwdriver. The probe is made from an old set of
tweezers broken apart and separated by a wood block of some sort. It ain't
fancy. And it certainly ain't complicated!
 
You don't really need any kind of indicator that current is flowing. You can
kind of feel and hear the thing in operation.
 
They are not, nor were they ever intended to be, a cure-all device. Nor are they
the magical fix for the Dreaded Verdigris. They do one thing, and that only:
they heat the center pin and dry out flange felt. In the process they tend to
shrink and "iron" the felt some. Used correctly the effect is frequently long
term. 
 
Like most tools it takes some getting used to. Yes, it is possible to burn the
wood in the flange fork. But, using a 6.3 vas transformer, it does take some
doing. I do remember encountering a few actions in which using the zapper did
loosen the pin in the fork but these pins were already on the loose side
and--though this is a guess on my part--I suspected the wood was a bit on the
soft side. Not ever action builder used hard maple, you know.
 
I stopped using it, not because it didn't work, but because I rarely, these
days, work on actions with original action centers. If I come across an action
with a bunch of sluggish action centers that needed a quick and cheap fix I'll
probably start hollering at Ryan to get the thing back.
 
ddf
Delwin D Fandrich
Piano Design & Manufacturing Consultant
620 South Tower Avenue
Centralia, Washington 98531  USA
Phone  360.736.7563
Cell  360.388.6525
Fax  360.736.5239
 <mailto:E-maildel at fandrichpiano.com> E-mail 1: del at fandrichpiano.com
E-mail 2:  <mailto:ddfandrich at gmail.com> ddfandrich at gmail.com

 

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