Allen ADC-222 issue

[Reedorgansforever]

I purchased a mid-90's Allen ADC-222 yesterday from a small local Baptist church. They hadn't used it in about ten years. It played alright when I tried it out a few months ago, although there was some distortion on full organ at high volume (internal speakers.) I figured, “ok, a few minor issues, no big deal.” I bought it to practice on at home, if the nearby church where I serve as organist/pianist is too cold during the week. Anyways, the Allen suddenly has a major problem. It develops a NASTY distortion/crackle in the sound if I use the swell reeds, or the 8' Diapason on the great+16' in the pedal. This is accompanied by a strange sort of “surging” in and out of the sound when this happens, and the awful distortion is still there, even if I close the expression pedal all the way. The flute and string stops don't act this way at all, and the sound is fine when only they are used. I've tried “exercising” the pots, as well as turning the volume knobs on the amplifier, to no avail. What gives?

[jbird604]

Thanks for posting your question here. I would have loved to help you privately, but as I've often remarked here on the forum, it does a lot more good for a lot more people when we talk about issues like this on the open forum.

I've been pondering this since yesterday, trying to think of a sure solution. You exercised the pots, including the amplifier volume knobs, no improvement. There are no foam-surround speakers in the 222, so unlikely to be speaker issue. Is there a headphone jack? If so, does it sound better with headphones?

Also, I'm not sure about the 222, but I know the 220 and possibly the 221 had some jacks on the back of the console down at floor level for connecting external speakers. This odd arrangement was unlike the speaker outputs on any other Allen models, and there were some problems possible with those jacks. I've had cases where the jacks developed poor conductivity on the "normally-closed" pass through terminal of the jack. You might look for those and make sure the jacks are clean and functioning properly.

One other maintenance issue to address is the RCA plugs and jacks. They can develop a layer of corrosion on the mating surfaces that is invisible but which creates connectivity problems that can lead to distortion. So be sure to pull out each RCA plug, wipe a tiny bit of Vaseline or your favorite electronic cleaner/lube onto the center tip and also onto the inside of the outer part of the plug. Clean whatever you can see of the jack as well. Do this at the cage outputs, at the inputs and outputs of the audio processor board, trem units, and all other assemblies within the audio chain. Then do this at the amplifier inputs.

There is also some value in un-plugging and re-plugging anything else in the console that is removable, including chips on the various boards. At the very least you should press down a bit on all socketed chips to make sure they are firmly seated. If they "crunch" when you press, that may indicate that the chip had backed out of the socket a bit.

If this organ has the D-40 amplifier, these have failed in some cases, but usually with smoke. But you can always reverse the RCA inputs to the two channels and see if the problem moves to a different set of stops. Be careful not to overplay with the cables reversed, as the pedals will then be sounding through the channel with only an 8" woofer, which is not meant to handle those frequencies. But it is ok to test it for a minute like that, then put the cables back.

Be sure to measure the power supply voltages, which are +5, +15, and -15 in the cage, and there may be other supplies as well, depending on options installed. There have been problems with the cage power supplies on MADC and MDS organs with the small cage., but if they measure ok you are probably alright.

If the antiphonal relay is installed in this one, and if you are using only the internal speakers, be sure the two small jumper wires are still in place between the "amp" and "ant" terminals on the relay assembly. This will rule out the possibility that the relay contacts have become flaky and are producing distortion.

There is a chance that you can clean up the sound somewhat with careful voicing, if nothing else helps. Turning down the treble pot quite a bit on each channel may help. Also, be sure the bass pot on channel two is not turned up too high, along with the bass boost pot on the audio processor board. These can produce distortion if over used.

The fact that the organ was not played for 10 years is worrisome, as lots of troubles can develop from disuse. But you should be able to revive it with care. The sound may never be anywhere near as exciting as on your reed organs or pipe organs you play in churches, but it should be a pleasant enough practice organ.

Let me know how it goes.

[John Vanderlee]

I have a 221 and is does NOT have the output jacks. It does however have a headphone jack and inserting the headphone plug activates a speaker relay that is tied into a terminal strip that also has the two jumpers JBird talks about. All of these are areas of possible bad contact if you have the headphone jack which is located on the right under the key desk .
John