Help with Allen 603-3DK

[Frankd]

Hello all,

I am very experienced in electronic repair, but not much experience with organs themselves. Last Sunday, I sat in a different spot and noticed that the 2 speakers in the front of our church weren't working, but both sets in the rear were. When I asked the choir director about them, she told me that they've been out since the organ was serviced about 6 months ago. In a separate cabinet, there are 2 identical amplifiers that have 2 channels (A & B) and they have been updated, and were made in 2001 ( the organ was made in 1980). After service, I could tell which was front and which was rear because one was warmer than the other. There is an RCA cable going to the front amplifiers from a power supply (it's labeled power supply, but obviously it does more), and when I unplug it I can hear the front speakers hum when the shield clears the plug. This indicates to me that the problem is in the organ itself, but I was wondering if it's possible that something is selected wrong on the console. Any ideas?

Thanks for the help,

Frank D.

[toodles]

The source of signal in the console might be unplugged. That's where I'd start.

[Frankd]

I opened the console and looked for a cable unpluged before writing the question above!!! I didn't see anything loose. I put it all back together, and when I went to choir practice last night, everybody wanted to know what I did to the organ.....the front speakers were working great. I explained that I really didn't do anything, that I'd just opened it up and looked around. I talked to the organist after practice (she's 91 years old), and she told me that she'd moved some controls, but said that she'd tried that several times before.

I do have a question though....I saw 4 cables going to the amplifier inputs. These connectors had what appeared to be "F" or cable TV connectors, and the co-ax may have been RG-59 size. I looked for the other end in the console, but didn't see them. Where are they hooked in the organ? Are they "F" connectors on the console end also? I imagine that they are in the bunch of cables that come out the center on the bottom of the console back cover. Now that I think of it, maybe one of them was being pulled tight before I took the back cover off and when I put it back on it could have ended up in a slightly different position and that's why it works now. I'm not going to look a gift horse in the mouth.

Frank

[toodles]

Back in the analog days, Allen used coax cabling between the console & remote amplifiers--just carrying audio signal. That connector was similar to an F connector, but a smaller size; I think with the MOS organs they changed to standard F size connector, though I'm not sure of the cable type itself. This is audio signal running from the output boards of the organ to the remote amplifiers.

Yes, they go out of the console to the remote amplifier rack. Perhaps it is a loose connector where they attach to the console--it is safe to tighten those. Also, could be an intermittent cable termination--it would be OK to disconnect & examine the connector. Just a single stray ground wire to the conductor would be enough to short out the signal.

[myorgan]

Please forgive me for asking the obvious, but does that organ have antiphonal relays? Perhaps the organist unknowingly is using the antiphonals only and mistakenly turned the main organ off?

Michael

[Frankd]

If the problem comes back, I'll check the co-ax connections in the console and make sure they're tight.

Are the antiphonal relays those in the remote amplifier rack? Or are they in the console themselves? Yes, there is a possibility that the organist didn't have something selected, but she and the choir director said that they'd checked that several times. And no problem asking because I have no organ experience and it isn't obvious to me.

[toodles]

I'm not sure, but good wiring practices would have the antiphonal relays at the amplifier rack rather than taking the speaker signals back into the console. But anything is possible--the key question is, do speaker wires run from the amp rack back to the console or directly to the speakers?

[cwielus]

These Organs have an On/Off switch for each computer for tuning purposes. If the Organ was recently serviced it it possible that one computer was turned off. The switches are located directly beside each MOS board and it's a chrome toggle. Right in front of you as soon as you remove the back cover.

Chris