Grounded Outlets and Dish
Warps
Some time ago, I answered an e-mail
from a reader who didn't think the electrical outlets in his 40-year-old house were
grounded. I said that they undoubtedly were, but not in the U-ground form that is used
today. I suggested he simply run a ground wire to the screw that fastens the switchplate.
I mentioned this to an acquaintance, who wrote, "I am
not an electrician but I think other people may assume from your answer that they could
solve the problem in this manner. This would be a dangerous assumption. When I bought my
current house I saw there was a new main panel with new wiring. All of the outlets were of
the three-prong variety. Upon closer inspection after I moved in I noticed some old
wiring. Using an outlet tester I confirmed that these particular outlets were not
grounded."
That reminded me that, in my own house, the wiring in the
family room had evidently been done by the former owner rather than an electrician, and
several of the outlets were in fact not grounded. It’s worth checking this out in
your own home, for safety’s sake.
Another reader wrote, "I'm an independent consultant
for musical legal rights and copyright law, as well as a music record collector, trader,
and search service. Every now and then I buy a vinyl record where the edges of the record
seem to curve up. Basically the record appears to be slightly bent and not perfectly flat.
Is there any way to repair this without damaging the surface of the record?"
That kind of deformation is called a "dish warp."
Depending on how severe it is you may not have to do anything. Some records warped in this
way will still play, although often the sloping surface will cause the stylus to skate
downwards, making a horrendous noise. Backing off on the tracking force can sometimes
help, but that runs the risk of mistracking, in which the stylus leaves the record surface
momentarily, and then comes crashing down. This sounds awful and can harm both the stylus
and the record.
The classic way to fix this and other warps is to place the
record between two flat surfaces -- sheets of glass are usually recommended -- weighted
down and placed in a warm oven for several hours. It's a tricky process, however, and a
tiny bit too much heat can ruin the record.
If the purpose is to get one good play in order to transfer
the disc to some other medium, you can temporarily flatten it. For one side, where the
edges curve downwards, a weight placed in the center of the record will do the trick.
Don't aim for perfect flatness, just enough so that the stylus can negotiate the grooves.
For the other side, where the edge curves up, I've had good success using short strips of
strapping tape to pull the rim down to the turntable platter. Again, perfect flatness is
not necessary, but the vinyl should be pulled down evenly in all directions or audible
warps may remain. I've found that a minimum of four pieces of tape is necessary.
...Ian G. Masters
ian@mastersonaudio.com
|
