Allen 603D right computer

[Diapason92]

Hey, i just received an Allen 603D organ that still works, but that is missing the right computer. it is an mos organ that has two computers in it, the right and the left. the organ is just running off the left right now, but there are two 32ft pedal stops that do not work and i suspect that it is because the stops are carried in the right computer. is there any of you guys that have or know were i may be able to find the right computer for my organ?

[circa1949]

Hhhhmmmm. I'm not sure if Allen will actually sell you one; their policy is to repair their older organs, not rehabilitate and rebuild them. If you have a dead one, you can pay for an exchange but even that is very pricey. Which is understandable, as no other technical company on planet earth is supporting products they made in the 1970s with parts.

That leaves a long wait on ebay for one to show up; but there are definitely some out that not being used, as people convert consoles for Hauptwerk or whatnot. This is a good place to start looking!

This is the way Allen support works for any digital organ. You contact your local dealer. If you are lucky, you get one that is easy to deal with.
If they agree to readily help you, they will find the cost of the new or refurbished replacement part and order it for you. Allen has parts to maintain all organs they have ever made, for a price.

[OrgansR4Me]

If you Email Allen for technical support with the model and serial number they may not have the part but can possibly supply you with historic technical information so you know the spec that you are searching for so you don't loose money getting the wrong part from the aftermarket. Have you noticed any other stops missing? It would seem suspect that you wouldn't hear other flaws from the missing computer?

[don60]

The second computer in this organ was used to double the stops for a better chorus effect, so its absence would not be very noticeable. The 32' pedal stops were produced in just one of the computers, however, presumably to avoid an unrealistic beat or pulsation caused by two low-frequency tones playing together.

A good resource for MOS-era Allen parts is organ dealers who sell other brands. They often take in used Allens in trade and in many cases strip them for parts. Several part numbers were used for MOS 1 computers, so the advice given above is good: try to find out exactly what board was fitted to your organ originally. Some of the boards interchange electrically but have different stop lists; obviously you need to have identical stops on the doubled ranks!

[Diapason92]

OK thanks guys, but i got to looking and found that what i was calling a computer is a keyboard array. that is whats missing. i really wish that i could get the 32ft stops to work, that is my favorite. i have contacted the Allen Organ Company with no reply so i don't think they will be much help. i don't know i cant find much information on this model of organ maybe i will post a pic and see if anyone recognizes it.

[don60]

Keyboard arrays come up on eBay rather often. At the moment I see two auctions for stopboard arrays, the companion parts that encode (oddly enough) the stops. Again, contact an organ dealer who might be parting out an old Allen if you do not want to take your chances on an auction.

You could move the other keyboard array into the empty slot and regain the 32' pedal stops.

[Diapason92]

well actually i found the problem. it was not the keyboard array. i did just as you suggested and it turned out not to be the problem. i don't really know how to describe how i fixed it but i did. the organ has a tone strip with three pegs sticking out of the backside for each stop. the first two of these had to be joined for the 32 to work. i am so happy!:->

[OrgansR4Me]

Happy as well that you traced the fault and found a simple connection problem. For your future use when we speak of contacting Allen the results are best when you go through your regional representative. They usually have a home page with an email link to their service department. Allen headquarters will always refer you back to the regional representative when you contact them directly. You may get some information later. If not contact a local church that may be dealing with Allen Service and if all else fails do an internet search on Allen organ sales and you'll be able to pick the result for your area. Not sure but the allen homesite may also have a link to help you locate dealers.

Don't know if this would be like your missing "computer" but a very nice board is selling now on Ebay at http://www.--------/itm/Allen-Organ-...item27cf46d0ae

[Diapason92]

thank you for the ebay post, but that is not what i need. i have recently found that the locale Allen dealer for my area is that people that gave me the organ in the fist place! i feel so stupid. well i have contacted them and am waiting to hear back. another thing my organ has five blank stops, does anyone know if it is possible to add tones to these stops?

[OrgansR4Me]

These blanks were indeed used on custom purchases. May take a little engineering to replace what was previously available but they are definitely working tabs. My last ADC self contained organ had 2 32' pedal voices added with the blanks that come on the lower left keycheek as well as random motion and some other effects.

[Diapason92]

thats pretty cool, but i wonder how i would even go about adding stops. is there some kind of electrical components that must be added?

[OrgansR4Me]

Voicing networks or whatever feature boards you'd want to activate would have to be wired to the tab. J Bird or Arie would be best qualified to speak to the work involved since they often improve the organs they work on. I'm not aware that any unmarked feature would be hidden already within you instrument. When used, the blanks were most often filled during the factory order from what I understand.

[jbird604]

Too bad you don't have parts to make both computer systems function because you're not hearing the lovely chorus effect that is produced by the two systems being every so slightly offset in tuning. Also, the celeste tuning function is not working properly without both computers. Maybe if you watch ebay you'll get the chance to buy the missing part at a reasonable price. I'd think that would be the best first upgrade to make to this organ.

Small MOS organs were usually sold without the 32' stops and sometimes a few other stops were not enabled, and these could be elicited by adding tabs to simply ground the appropriate pins on the stopboard array or on the motherboard (depending on the stop). However, I think the 603 probably already uses all the stops resident on the computer boards. The reason you were missing your 32's was because they are normally tied to only one of the computer systems instead of both. The one that is disabled in your organ is the one that would normally have given you your 32' stops, so you worked around that by wiring them to the secondary computer. Nothing wrong with that, but eventually you might have both computers working and then you might find them too overpowering coming from both systems.

MOS is actually a fascinating technology and one can do a lot of good stuff with these old organs. Too bad the documentation is a little hard to get from Allen. You have a good organ to practice on and enjoy. Hang onto it and keep up the good work.

[circa1949]

Too bad you don't have parts to make both computer systems function because you're not hearing the lovely chorus effect that is produced by the two systems being every so slightly offset in tuning.

Jbird, as always, you da man. I don't know where MOS or ADC owners would be without you! But, it's worth mentioning that this could all be mitigated - in theory - not only by fixing the 2nd computer, but buying a semi-powerful outboard effects unit (i.e., recent Lexicon or something >= MPX-1 from the past) and running an chorus program. You'd need to also run an EQ program if you want to bypass the pedals. At that point, the unit may or may not still be capable of running a reverb. My former MPX-1 would sometime add tiny glitches to pitch shifting if it was also reverbing. It was getting a little overloaded. I doubt the newest have this problem, but of course they aren't exactly cheap. I didn't chorus with mine, but I did shift one channel down a bit, so as to make the MADC-3 system have 3 effective frequency maps instead of 2. Just a little bit of this really helped open up big ensemble registrations. As we know, nowadays a Quantum organ surely has a separate frequency map for every output channel, as that most closely mirrors a pipe organ. Surely, an organ like the giant Johannus in Virginia would have sounded very cold if all 70 channels were lock step in tune with each other. Its tremendous realism was because they were not.

[jbird604]

I'm interested in that concept. If I wind up using this analog Rodgers at church, a pitch-shift would be nice since it only has two ranks of oscillators (plus a celeste), so all the divisions are basically locked in tune with nothing to distinguish them except the separate speakers. I gotta get another MIDIverb4 and give that a try on this one. I remember using it several years ago to add some chorus to another old analog Rodgers.

With the Allen 603 in question here, it would be so much better an organ if he could get both systems running, not only for the chorus and celeste, but to preserve the channeling that Allen worked out. Some of the stops come from both systems but some of them may be in only one or the other. And the tuning scheme is somewhat more complex than just slightly sharp in one computer. When you switch to celeste tuning, the unison computer will be in "stretch tuning" mode and the sharp computer will be in "straight" tuning mode, giving a better celeste scaling than would be possible with a digital processor.

If he keeps an eye out, he might pick up a complete MOS1 organ for a few hundred dollars and have a good supply of spare parts!