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MMD > Archives > March 2009 > 2009.03.07 > 08Prev  Next


Ampico A Rewind Problem & Relative Humidity
By Bruce Clark

If your Ampico is refusing to rewind, it sounds like there is a leak
in the repeat system causing the rewind and repeat to be on at the
same time and oppose each other.

To test this theory, locate the hose to the repeat valve on the side
of the rewind-repeat pneumatics, and pinch it tightly closed it so no
air is admitted.  Now test the roll when the perforation in the roll
uncovers port #8T on the tracker bar.  If this solves the problem,
there is a leak somewhere along the many hoses that send the signal
to the repeat pneumatic.

I would suspect the rotating repeat switch itself.  Often the pot
metal expands with age and leaks can occur.  Test it for leaks.  If the
leak is caused by the pot metal valve, and the valve is not too badly
damaged, it can be resurfaced by lightly sanding both surfaces of the
valve, using very fine sandpaper with a piece of glass under it to
insure the surfaces are completely flat.

The hose directly leading from the repeat pneumatic is attached to
the moving part of this switch.  Often a leak is found where the hose
connects at this moving part.  See Figure 35 in illustration 7 in the
service manual.

If the leak is not found at this point, continue up the line making
certain the valve boxes are not leaking at their gaskets.  Heating
the home in winter will often cause indoor humidity to decrease
dramatically.  Leaks will occur because of wood shrinkage at gasketed
surfaces.

I cannot stress this enough, and will repeat it again:  Keep the
relative humidity as steady as possible in the room where the piano is
located.  This is overlooked by many.  Drastic changes in humidity
will eventually damage anything made of wood.

Invest in an inexpensive humidity gauge.  Place it on your piano and
keep track of the readings.  The actual percentage of humidity is not
as important as keeping it steady year round.  Therefore if you find
that your relative humidity today is 25%, 35%, or 50%, then keep it at
that year round.  This may involve placing a de-humidifier in the room
in summer, and a humidifier in the room in winter.  The effort is worth
it, in the long run.

If the humidity within your home is very low during the winter heating
season, you may have to place several open containers of water inside
the bottom of the piano, as well as containers of water behind it.  Be
sure they are kept full when it is dry, and removed in the spring after
the heating season is over.

Bruce Clark


(Message sent Sat 7 Mar 2009, 13:08:06 GMT, from time zone GMT-0500.)

Key Words in Subject:  Ampico, Humidity, Problem, Relative, Rewind

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