Testing 12/inch Player Organs
By Richard Vance
The technique of using a 58-note (6/in.) test roll to test a 116-note (12/in.) Aeolian organ is usable because the two alternate rows of tracker ports, each themselves spaced at 6 to the inch, are tested separately, and so the big holes in the 58-note format can be made to cover either the upper or the lower row of ports by a slight adjustment of the tracking device.
However, this technique cannot be applied to the Hammond format, or the Skinner format from which the Hammond format was derived, because all of the 116 ports are used simultaneously. Also, the big holes in the 58-note roll are too wide to uncover only one port at a time, even if testing the Hammond could be theoretically done "every-other-hole".
Commercial supply of a new test roll for the Hammond, or any 12/in. format system, must await the completion of a 12/in. production punch. Such an effort is now ongoing, but the operational date cannot yet be predicted.
Even for the Aeolian Organ, such a test using a 58 note-roll is functionally incomplete, serving only to check that the system is working as a whole. The complete functional test and individual debugging of each note requires either a proper 12/in. test roll, or the alternate method I use, described below. This is because, in any 12/in. system, the tracker port is very large compared with the tiny hole in the paper and the even tinier bleed used to read it. Any test involving uncovering the entire port might 'pass' even if there were large leaks in parallel with the bleed.
The way I do this is as follows. First, tape over the tracker bar; I use 6-line paper correcting tape rather than masking or Scotch tape because it makes a neater hole. Select a sewing needle which will just pass through the punched hole on a roll, and pierce the tape in the center of a port. Using the finger, uncover the pinhole for testing. When one note is done, cover the hole with a scrap of Scotch tape and move on to the next.
Although this method seems elaborate, it is actually more quickly done than described, and leads to a reliable and accurate result. It has the additional advantage that it enables the initial debugging to be done at leisure, allowing one to stop and fix any individual bad note; and enables one to work hands-free, without having to stop a roll with one port uncovered and trying to keep the roll tight over the bar while working.
Richard Vance
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(Message sent Sun 23 Feb 1997, 15:06:49 GMT, from time zone GMT.) |
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