Robbie, I think that you have probably overlooked something in the
Ampico B schematic. Check also fig. 28.
The C valve doesn't operate both A and D, just D. It is energized on
reroll, and then only if the repeat switch is turned on. Otherwise,
it energizes as soon as the roll comes off the trackerbar (5B), which
actuates the motor off switch through the bled pneumatic in about 3
seconds or so.
The motor switch pneumatic and the repeat pneumatic are in parallel
and operate together. That is why you will always find the play lever
ready and in play mode position, even when you didn't have repeat on.
(It is also why, sometimes, the model B replays a roll when its tab
hook didn't get unlatched in time.)
The C valve often has cardboard on top to slow the return of the
poppet and give the repeat bellows more time to close (because of drive
friction, the bellows has to have time to build up to full pressure).
If the cardboard was sealed (as D.L. thought), then you would in effect
have vacuum to the repeat valve all the time, and every time the roll
opened 5B the repeat pneumatic would close.
You are welcome to use this letter, but I thought maybe you would like
to make your own correction.
[ Thanks for the additional explanation, Craig. The Ampico 1929
[ manual and the pianos I've seen don't have the cardboard on the
[ valves, so your experience will be helpful to techs when the
[ cardboard is encountered. -- Robbie