Allen Protégé AP-4 - Some stops not working

[Guest]

Hello all

I'm new here, so hoping some one can help!

I'm one of two organists from the Parish of Portaferry in Northern Ireland. Been organist here for just over twelve years, started when I was 13. We have two churches, one church, St. Patrick's Church, with an Allen Protégé AP-4, and the other, St. Cooey's Oratory, has an Allen Protégé C-2a. Anyways, enough about me...

We have the Protégé AP-4 in our main church (we had this installed in 1996, I believe), and we are having a problem with it. When you turn the console on, 15 out of 27 speaking stops don't work (I can't remember off-hand what ones they are exactly, but I know stops including the Diapason and Chimes on the Great, and the Spitzprinzipal on the Swell do not work. We would leave the organ on at least two hours before Mass began, and eventually the other stops would work. But this no longer seems to work. It's really frustrating. Most of the stops that don't work are the ones that provide the backbone to the rest, so it's not the best sound as it stands.

Does anyone happen to have any ideas of what the issue would be? Our engineer is calling down in a fortnight to have a look, but I'm just curious as to what the issue? The last thing we need is to have to buy a new organ!

Many thanks,

[jbird604]

Sounds like you are losing one of the audio channels. The AP-4 is of the "W-5" type, the last series of MDS models from Allen. A very nice system that produces very good organ sounds when properly voiced and installed.

Since the sound used to come in after it got warmed up, it sounds like there is a connection issue in the audio path. As with almost any audio problem in a digital organ, I recommend a basic maintenance routine. This is simple stuff that you can do yourself.

First of all, since the most common cause of a dead audio channel is a dirty "pot" or volume control, you need to "exercise" the pots associated with the audio system in the organ. On the amplifier itself you will have two volume control pots. If the amplifier is the most common type it will have two black knobs with numbers from zero to 10 on it. Make note of the number it is set on, then exercise it by twirling it back and forth several times from zero to 10, then return it to about the same spot you found it. Do this to both pots, then see if you now have all the stops playing.

Next step is to check the audio cables that run from the generator cage to the amplifiers. You should see a pair of grey vinyl covered audio wires going into the amp with RCA plugs. Carefully disconnect each one with an easy twist and pull, wipe away any corrosion you see (I use petroleum jelly to clean up these plugs, then wipe it away with a paper towel or soft cloth). Then gently but firmly re-insert. Follow these cables back to the generator cage, and do the same thing where they come out of the cage, and also if they happen to plug into any other boards or assemblies in the organ.

One more crucial step is to exercise the miniature pots in the voicing section of the generator. You should see a metal face plate that has four rows of small holes with a screw-driver adjustable pot behind each one. You need a miniature screwdriver that just fits the slots in these pots in order to adjust them. They are marked with the letters B, T, G, and W in each row. And the rows may be marked as channels one through four. The "G" pot in each row is the "gain" control for that channel, and these are the pots that are notorious for getting "dead spots" which will cause stops to be dead. Make a note of the position of each pot so you can return it to about the same spot later. Then exercise each pot by turning it back and forth a dozen or so times.

While you're inside the organ, check all the cables and connectors everywhere. There are a number of disconnectable cables, and you should gently pull and push on each one to make sure it is firmly seated on the pins or in the sockets to which they attach. On the amplifier you have a row of screw terminals holding down a fanning strip. You might want to loose each screw and then tighten it back down.

If the organ is equipped with antiphonal relays, these can also be a problem. they will be in the floor of the console. Make sure the screws along one edge are tight, and you might even wiggle the wires or poke around gently on the little pc board to see if the sound happens to pop on. If so, that might indicate a problem with the relay.

Going through all this may fix it, and if not, then the problem is more serious. Could be a dead amplifier channel, which is often due to a failed mute relay inside the amplifier chassis. But problems like that may have to be addressed by a qualified Allen tech.

Good luck!