Player piano vent block diagnosis

[D.L. Bullock]

WHOA just a minute

The problem stack Greg describes is not made by Amphion, guy.  It is a
Laffargue.  What he describes is either an unrebuilt set of valves or one
that was rebuilt with sponge neoprene instead of the leather that it needed.

An Amphion upside down valve block is one of the best working systems there
is.  It was also used in early Ampico reproducers and I am presently
restoring one of those with those valves from 1927.  I have done more than
50 sets of those valves and I have NEVER had one that had problems seating.
If you have had that problem, the player you had must need restoration by
someone who knows how to do it.

D.L. Bullock    St. Louis
www.thepianoworld.com <http://www.thepianoworld.com>

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-----Original Message-----
From: Ron Nossaman [mailto:rnossaman@cox.net]
Sent: Wednesday, March 02, 2005 1:01 AM
To: Pianotech
Subject: Re: Player piano vent block diagnosis



> I wanted to call this subject "Players suck" just to
> get some attention, but refrained.  Technically
> correct, but often mistaken for a disrespectful value
> judgement.
>
> My problem:  customer's Laffarge upright player, built
> 1919, player action nicely rebuilt 1970, still very
> clean and tight, works great, EXCEPT...
>
> When starting a roll, there is the sound of a major
> vacuum leak.  The spool turns slowly, but no keys
> play.  You have to turn the electric vac up to full
> power, something pops shut, then the piano plays
> perfectly, even after slowing the vac back down to the
> minimum.  The pump is tight, the motor is tight, the
> action stack leaks only a little at the end gaskets.
>
> I think the action cutoff "gate box and vent block",
> between the pump reservoir and action stack is
> malfunctioning.  It appears externally to be exactly
> like the photo in Reblitz's "Player Piano...", page
> 106, Illus. 6-17, third printing, 1986.
>
> I didn't have time to take it apart, but was hoping an
> expert would have an idea why this valve would be slow
> to close, needing very high vacuum.  Any advice?
> Quick fix?  Something else wrong?
>
> Greg Graham
> Closet player piano aficionado in denial


It's likely an Amphion action, which means the valves are mounted
upside down. Even with a with a good rebuild and a minimal 0.030"
valve gap (neither of which is likely), 80+ valves all leaking that
little bit until enough vacuum can be generated to suck them all up
to seat will drain the system down. There's no field repair for poor
design, so I'd expect you won't fix it with adjustments to the stack
cutoff.
Ron N