Player Piano Pneumatic Rewind

[atonal@telusplanet.net]

Greetings techs, 

I need some advice on a D.W. Karn player piano, Woodstock, 
Canada. I have repaired bellows & tubing, and as the tubing was 
ossified, I have completely redone it. The tracker bar works fine, 
the auto-sustain and expression switches are fine, the pneumatic 
tracking centering device works well: the only problem is getting 
the upper stack pneumatic cutoff to engage when rewinding. The 
transmission is working well ( I carefully disassembled it and 
cleaned all parts, re-assembling them in the same spots, and 
mechnically it works fine). 

There is a valve mounted to the back of the spool box that dis-
engages when the rewind switch is engaged. This has to be the 
source of the pneumatic cutoff to the upper stack, as there is no 
mechanical linkage in the lower bellows, as I have seen on other 
player pianos, and the rewind lever is in the spool box. The valve in 
question has four small nipples on the bottom, two large nipples on 
the right hand side (which should be logically tubed to the two large 
nipples which are case mounted on that side) a small nipple on the 
top and a small nipple on the left side: total : 8 tubes run into this 
modest slider valve. The bottom four are open (allow air through) 
when the slider is in rewind position, the large ones on the side are 
closed in that position, and the two top and left are open. There are 
two rewind holes at the end of the note holes in the tracker bar.

I have tried all conceivable combinations of tubing arrangement with 
this valve, some using lead tubing splicers (which I found in the 
bottom of the piano) and running to the only tubing nipples that are 
left once the other automatics are connected & working.

The player will rewind, but the upper stack pressure doesn't cut off. 

This has become a serious head-scratcher, as I haven't worked 
with a completely pneumatic cutoff system before...

Any suggestions, clarifications, and tubing diagrams would be 
cheerfully accepted.

Regards, 



Rob Kiddell RPT
Atonal Piano Service
http://www.atonal.ca