[ Ref. David Greene in 130209 MMDigest --

David Greene asks several questions about the Ampico "B" drawer which
I will address thusly:

A.  With regard to collapsed or crushed tubes, from David's description
I initially thought the previous re-builder might have used tubing with
a wall thickness that was too thin; however, if this were the case, it
is unlikely that the cover panels, when replaced would have pressed
hard enough on the (two) layers of tubes to cause blockage.

Conversely, use of tubing that had a thicker wall thickness than
original would have resisted compression blocking better but would
likely have also caused "bulging" of some of the cover panels.  Since
he did not mention this, I am inclined to think the present tubing is
too thin and that he is experiencing "kinking" at some of the sharp
radius guide channels in the wood.  This could be complicated by the
tubing having been pulled too tightly during installation which will
lead to corner compression and kinking as it ages.

There are (at least) two ways to handle this problem: 1) Obtain some
brass tubing (hobby shops are a good source) of a diameter which will
just fit inside the tubing I.D. without expanding it.  You may also
need an actual tubing bender, but fabricate elbows of the proper angle
(which will probably be greater than 90 degrees, cut the tubes at the
kink point and insert the elbows with a small amount of PVC-E glue
applied to each end to insure an airtight seal.

Or (2), With a chisel, wood rasp or other suitable wood-working tool,
remove some wood at the corners where the kinks are occurring, making a
larger radius which, in turn, will reduce kinking.  You should also
make sure that all the tubes run neatly through the flat metal
"dressing" brackets and do not cross each other which will lead to
compression blockage when the cover panels are replaced, no matter what
the wall thickness.  In some portions of the runs, dressing of the
tubes was done with woven cotton straps similar to shoe laces.  Make
sure these or a similar constraining device are in place.

B.  With regard to the subdue function, in early models that do not
have the subdue switch on the bass side of the drawer, look for a
sliding switch that is usually mounted on the inside of the rim in the
vicinity of the curve on the treble side of the case, and usually near
the First Intensity adjuster.  (I have sent a photo to Robbie for the
MMD Archives.)

It is about an inch and a half square with 5 tubes attached (the top
one not visible in the photo.)  At the moment I do not remember which
position is "Normal" and which is "Subdued" and there are no markings
that tell you.  I also don't remember where all of the tubes hook-up
and my only customer with a "B" of this design is several hours away,
but one or more likely go into the First Intensity Adjuster.

C.  The re-roll brake is easier on rolls since it only operates
intermittently under control of the pallet valve operated by the slowly
revolving cam on the motor transmission.  But this brake drum is on the
left-hand side of the drawer on the extended axle of the take-up spool,
with a narrow spring steel band wrapped in (usually) green felt which
makes one and a half wraps around the drum.

From David's description I am wondering if he is actually describing
the Play brake which is mounted on the extended axle of the supply
spool on the right-hand side.  This drum has only a one-half wrap of
woven cotton material to exert a retarding force on the paper to keep
it from "burbling" over the tracker bar.

Either brake can theoretically cause tearing of the paper if it is
in extremely fragile condition, but it would be difficult to apply
enough vacuum to the play brake pneumatic (which passes through the
"throttling" valve connected to the paper thickness sensing lever on
the bottom right-hand side of the take-up spool compartment).

It would likewise be difficult to have the re-wind brake pneumatic so
over-powered that it would damage the paper during the several short
applications that typically happen during re-wind.  These are roll
length dependent and are intended only to apply enough retarding force
to allow the layers of paper to wind tightly on the supply spool,
saving the operator that "drudgery" prior to playing the roll the next
time.

No matter which brake it is, I see no harm in returning it to its
proper functioning, but if in doing so you begin to have tearing
problems during re-wind, I would look to other maladjustments such
as making sure the tracking compensator is defaulting to a proper
center-of-its-excursion range during re-wind and that the take-up spool
is properly centered so that its flanges are equidistant from the
nominal center-line of the paper during play.

D.  The ability to "push down" the control knob of the repeat switch
is not a function to be used by the owner or operator, nor does it have
any effect on the operation of the Ampico, unless, of course, in doing
so the pin falls out and the bottom rotating disk of the switch then
falls to the bottom of the drawer.

You should avoid this possibility by NOT pressing the knob.  It is
simply an assembly design that allows dis-assembly of the switch by
the service technician if or when the switch malfunctions, typically
because of a build-up of paper perforation "lint" (or other obstruction)
which could conceivably block one or more of the passages internal to
the switch that would keep it from operating properly.  In the typical
Ampico "A" design for instance, all four of the rotating switches, as
well as some other manufacturers and mechanisms used this same
"pin-in-a-slot" design.

David, if possible, send me some digital photos of your problem areas
and I can analyze them more intelligently.  Thanks.

John Grant
reddawg@unameit.net.geentroep (remove .geentroep before replying)