Allen 603, no sound issue

[cwielus]

Hello,

Just got back from rochester to pickup a 603 mos 1 organ that I bought on ebay. All wired up in the barn to try and troubleshoot why there is no sound output (i bought it this way). Amps power up, organ powers up, capture action works. I have DAC boards and computers from a two 301-b organs (one that I use), and i know that they both function.. Can I swap these into the 603 to see if the boards are the issue. Any other suggestions welcomed and appreciated.

Thanks,

Chris

[jbird604]

Chris,

You can always swap MOS boards around for troubleshooting, with a few caveats. Any MOS-1 board will work in any MOS-1 computer, but if it's the wrong "code" some of the stops will be different. DAC boards may or may not have bass boost on them, and later DAC3 and DAC4 boards required + and - 15 volts brought to them on a small connector, but you can always pop in an original DAC or DAC2 to test any system. Clock boards, SBA, KBA -- all are interchangeable though KBA boards come in several varieties, some with remote sustain knobs or other unusual accessories. Tremulant gates and Random Motion boards are all identical.

It is unusual that you have no sound at all from either of the 603's two computer systems. Perhaps the un-muting voltage (delayed +12) is absent and the mutes are not getting opened. Listen for the click of the muting relays a few seconds after powering up. If it doesn't happen, you can always put a clip lead across from the incoming +12 to the delayed terminal (on the AC distribution box in the floor of the organ) to temporarily open the mutes. You can play the organ like that, but remove the clip lead before powering down or you'll get a nasty pop, and don't re-clip it until after power-up to avoid the turn-on whump.

That muting voltage is about the only thing I know of that is common to both systems. Of course, you may have a dead board of some kind in each one if the organ has been neglected or out of service for a long time.

[cwielus]

Thanks Jbird,

I swapped both mos boards, no change, checked for 12v, present (and delay click is heard). swapped in the single spare mos board that I have and we have sound! I have also swapped it into both locations in the console and have sound from each, although there are some keying issues on the swell in ONE position. Also no 32' or 16' pedal stops when the working mos board is in one position, but work fine when it is in the other slot. some cross talk from flute to the main channel (DAC board?) .

Thanks for your thoughts,

Chris

[jbird604]

The absence of the 32' and 16' stops on one side is not a malfunction. If you look at the tone strip you will find that the diodes for those stops are connected only to one system rather than both. This was done to keep these low stops in only one channel that could then be equipped with a subwoofer or an extra large speaker system, and to preclude odd out-phasing effects at these low frequencies.

The cross talk from flute to main may be intentional if the organ is of the "-3" ("dash-three") variety. Or if the spare MOS board you have happens to be the wrong "code" for your organ. If the model plate of the organ says "System 603-3" then it is supposed to have A-2-4-6 boards in both slots, but if it is "System 603" without the dash-three, the boards are supposed to be A-1-4-6. Using the wrong code board won't hurt anything, but a few of the stops will not be what the stop tab says and certain stops may come from the opposite audio channel.

Keep up the good work!

[cwielus]

Hello John,

The organ is a 603-D. It currently has an A-1-4-6-SP board and an A-1-4-7 board (neither if which seem to function) I have from my working organ and spares installed two A-1-4-6-FS boards. There is still some distortion although I do believe that the likely cause is the non-existant woofer foam in EVERY speaker. I'll be ordering foam kits tonight to address that issue. The "octaver" settings cause some very interesting action on the swell. When activated they cause quite a few sounds to play as well as quite a few notes. Almost sounds like it does if one does not move the transposer to the correct 'detent' and leaves it between settings so to speak. (christmas eve 2010...oops)
Otherwise things seem to function well. It has the nicer (non-floppy) dual combination action, came with tons of tone cards and is cosmetically excellent condition. Story is that it lived the same living room at a single ladies home until she passed away and left everything to the local university (who turned around and sold everything!).

Thanks for your kind assistance,

Chris

- - - Updated - - -

Here's a link to a quick video I shot with my Iphone (for some reason on its side...sorry)

http://www.youtube.com/watch?v=mIds-LDWJLE

[jbird604]

Don't know about the Octaver malfunction, could be a problem in the KBA board for one system, if I were guessing.

If the A-1-4-6-SP and A-1-4-7 boards were original to the system, that would make good sense. The -6 and -7 designate differing mixture compositions, which would have been interesting when used together, or maybe the organ was designed to have one stop for the -6 mixture and one for the -7 (perhaps a "Scharf" or other high-pitched mixture name).

The one board with "SP" indicates "slow pedal" and it would be the one that the 16' and 32' stops were wired to, so that these stops would speak slowly or seem to build up gradually in a pipelike fashion. The rest of the pedal stops would have been wired to both boards, and the quick attack of the non-SP board would have masked the slow attack of the other board, giving the pedal upperwork the necessary faster response.

Allen did some pretty cool stuff with MOS, considering the humble set of samples the reside on the MOS board. Another forum member recently posted about a large MOS organ set up with basically the powerful reeds in a channel by themselves, and Allen had done this with standard MOS boards and creative tone-strip wiring.

BTW, the replacement boards you are using are OK, though you will have lost the secondary mixtures or may find that the mixtures are not nearly as bright as they would be with a -7 board in the B slot. The "FS" designation indicates "frequency separation" which means that there is a subtle built-in tuning deviation between the flute and main channels, which further enriches the ensemble of the tone. This was a rather expensive option on MOS organs, so appreciate the richer sound you are getting!

Good luck re-foaming the cones. I never try to do that because I've found inexpensive rubber-surround woofers from MCM Electronics that work just fine in older Allen cabinets. But re-foaming is admirable because it preserves the old speakers and probably retains the original frequency balances better.

Enjoy your fine instrument!

[cwielus]

Thanks again John

I really appreciate the education on these boards. I like to know what I'm working with. Just spent an hour out in the garage playing the organ, it sounds pretty decent for having 6 poorly functioning woofers. A bit buzzy! I quite like the sound of these older allens, and they are quite enjoyable to work on.

regards,

Chris

[Tom Albrecht]

Also appreciating the free education. My 603DK is up and running well, with a little help from John a couple weeks ago. I'm paying a lot of attention to threads like this which divulge a little more about how the organ works. This will undoubtedly all come in very handy in the future if and when malfunctions arise.

Thanks again,

Tom

[cwielus]

Well, the 603 was installed into the church yesterday afternoon, running to about 3 am to get it sounding decent enough for todays service. Some person pulled over in front of the church when we had the old 301-b on the sidewalk, he wanted it for free, but it was a no-go, I'm keeping it for the time being. He would'nt stop talking to us, so we made him help lift the 603 off the truck and up the stairs!

Had a small combination action problem, that turned out to be # 3 & #4 general thumb piston contacts both making contact at the same time, due to the face board under the keyboard getting pushed back slightly. simple fix, but took hours to trace. Caused some very erratic action, including random action changes during a power cycle. Figured out that it had to do with #3 general, after I realized that the stop settings for that piston randomly set during power up or down.

Sounds great! I am still missing a 15" woofer on the left flute channel which should arrive this week. I have harrison reverb and Travelling wave generator on the right flute & main channel and have ordered another pair to go on the left channels.

Bass response is a little week above about Bb on the pedals, it may be the missing woofer on the left side.

Thanks again John for your help in getting this up and running.