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I am working on an early Allen Theater 15 electronic organ. I have most everything working and have the manuals and understand most of the electronics but I an not an organist. I have one problem that I can not figure which area of the sections the problems occur in.
The problem shows up only on the Solo manual, all keys C2 to the end of the manual. I select only the 8' Flute. All oscillators key on, but there is "chirp" at the beginning of the note after the key is depressed. If the key is held down, the "Chirp" goes away, but this is not the same as the "Sustain" which works fine. The fundamental oscillator sounds the same on the Accompaniment manual as it does on the Solo which says it is not an oscillator issue. The key oscillators are pure.
I would have thought is was a "Chiff" issue, but it is there whether the "C" stop is off or on and therefore happens anytime you play on the "Solo" from C2 to the end. I have tried to see if recycling the power changes or clears the issue but it does not. But there seems to be a slight difference between having the "C" stop on or off, but I can not really decipher the difference because the 'Chiff" is normally such a short pulse.
It seems to me that it must be a keying issue maybe like a shorted diode but the fact that it happens on every key I don't think I would have that many diodes that are shorted and pass the "Chirp" pulse through the "Chiff" coupling capacitors.
A friend with better ears than mine says the chirp frequency at the beginning of the note being played is a constant pitch and not the pitch of the note being played.
Could this "Chirp" come from a different gang switch? Are there some other tests I could try or even disable to see where the source of the noise is coming from?
At this point I would welcome any thoughts.
Thanks for listening to such a long post and for everyones willingness to advance the art of the organ.
Because I new using forum, if this post gets re-directed to somewhere else please tell me how to find out where it was re-directed.
Thank you
Craig Shull
The problem shows up only on the Solo manual, all keys C2 to the end of the manual. I select only the 8' Flute. All oscillators key on, but there is "chirp" at the beginning of the note after the key is depressed. If the key is held down, the "Chirp" goes away, but this is not the same as the "Sustain" which works fine. The fundamental oscillator sounds the same on the Accompaniment manual as it does on the Solo which says it is not an oscillator issue. The key oscillators are pure.
I would have thought is was a "Chiff" issue, but it is there whether the "C" stop is off or on and therefore happens anytime you play on the "Solo" from C2 to the end. I have tried to see if recycling the power changes or clears the issue but it does not. But there seems to be a slight difference between having the "C" stop on or off, but I can not really decipher the difference because the 'Chiff" is normally such a short pulse.
It seems to me that it must be a keying issue maybe like a shorted diode but the fact that it happens on every key I don't think I would have that many diodes that are shorted and pass the "Chirp" pulse through the "Chiff" coupling capacitors.
A friend with better ears than mine says the chirp frequency at the beginning of the note being played is a constant pitch and not the pitch of the note being played.
Could this "Chirp" come from a different gang switch? Are there some other tests I could try or even disable to see where the source of the noise is coming from?
At this point I would welcome any thoughts.
Thanks for listening to such a long post and for everyones willingness to advance the art of the organ.
Because I new using forum, if this post gets re-directed to somewhere else please tell me how to find out where it was re-directed.
Thank you
Craig Shull
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