Allen 123-3 C gremlins

[Guest]

Hi guys - 1st post from me, thanks for a great forum.

I have been working on my sons home organ Allen 123-3 C (late 1970's) trying to sort out the "gremlins" as I fondly call them

when a key (mostly in the flute section ) is sustained you get an odd chirp or gremlin sound - easy to replicate if holding a key down and actuate the stop in and out of contact.

thus far I replaced all the caps in the power supply and cleaned and reseated all edge connectors

I have checked all other RCA connections and had a uneventful time on the trim pots on the DAC board



Where should I poke next or am I on a thankless journey?

Apart from this the organ is in fantastic condition and was under a service contract until 2006 - I just want to get the best we can from it

Thanks for your time

Bill

[myorgan]

Where should I poke next or am I on a thankless journey?

Apart from this the organ is in fantastic condition and was under a service contract until 2006 - I just want to get the best we can from it

Bill,

You're going to think I'm crazy, but have you turned the ceiling fan off? My wife once played her violin under a ceiling fan, and it sounded like she was under water. Recently, a Forum member got an organ home, and couldn't diagnose the issues he was having with the sound--ceiling fan.

Otherwise, do you have a way of recording the issue so we could hear it? I use Audacity (free audio recording program) to record my audio.

Hope this helps somewhat.

Michael

[jbird604]

All MOS organs have a bit of a grungy chirp or crackle in the tone if you are holding down a note while turning stops on or off with the tabs. This is due to the slightly flaky switching action of these tabs. If you look at the rather primitive switches behind these tabs, you'll see that they are just thin pieces of metal that are brought into contact when the tab goes down.

Since the surfaces tend to get dusty and/or corroded over time, the connection becomes a little iffy, and the noise results. Cleaning up the mating surfaces will often help, but won't fully resolve the problem. I generally dip a Q-tip in alcohol and use it to wipe away as much of the black gunk as I can from the mating surfaces, then I may apply a very thin film of Vaseline to the same surfaces to prevent or retard future corrosion.

The good news is that the noise becomes less bothersome the more you play the organ, the more you exercise the tabs. And most players don't do a whole lot of flipping of the tabs while holding down notes, though of course that may need to be done sometimes. The noise will be quite inaudible when the presets are used to change the tone during playing, as they do their switching electronically rather than mechanically.