MOS1 Tape record/play adapter 911-0166 and 911-0165

[phisch2]

Greetings,
This is my first post but have been reading a lot as our church just acquired an Allen 301B. The Allen tech was out yesterday and swapped out our capture board, replaced a power supply module, replaced the main power switch, and reconnected a cut wire that was preventing 6 keys from sounding. Now the instrument is up and playing as it should be.

Anyway, there are two boxes mounted write under the tone generator board marked "Tape record adapter Ass'y 911-0166" and "Tape play adapter Ass'y 911-0165". The "play" adapter is not wired up at all and has a total of 4 RCA style connectors on it. The "record" adapter has three wires coming out of it, yellow, green, and black. The black wire is connected to ground on the 12V power supply, but the green and yellow wires are not connected. It has two RCA style plugs marked output, one for flute and the other for main. I'm assuming this is some kind of line-level output adapter? But where would the green and yellow wires be connected to? The corresponding amps? And what is the "tape play adapter" for. I've searched the forums and internet with the assembly numbers but come up empty, save one post that mentions the 911-0166, but no real information about what it is, how it works, etc.

I'd greatly appreciate any information that could be provided. We're looking for a line level output from this instrument if possible. Otherwise we can try a speaker-level to line-level converter, but if there is something already built in to the instrument, I'd rather do that.

Thanks and regards!
-Phil Schielke

[myorgan]

Phil,

Unfortunately, that's a new one on me! I am very curious to learn the answer as well. We have some great techs here who should weigh in shortly.

Thank you for becoming an active part of the Forum. I hope you continue to participate here for a time to come.

Michael

[phisch2]

Here is a picture of the devices in question if that helps.

[you795a]

I never seen them before but just a guess here is that the Tape Record Adapter would be to connect a tape recorder to record the organ. It might also be used to connect to a PA. Where do the yellow and green wires connect? Is the box on the left connected with any wires? If it isn't, I'd be curious and open it up to see what's inside of it.

[phisch2]

The yellow and green wire on the tape record box are not currently connected to anything. The black wire is connected to ground.

The tape play box has no wires coming out of it. Maybe just some kind of gain control? I could try to open it up at some point.

[myorgan]

Both boxes appear to be identical with the exception that the one on the right has the 3 wires on it. My first question is where the Black wire is connected to ground.

I wonder if the Yellow and Green wires take the signal from the amplifier to the box on the right, and either the signal coming from that box is then fed to the 2nd box. Both boxes have gain controls on them, so they're obviously used to regulate the signal.

Alternately, the box on the left could take an input signal that is Y-split from either the amplifier or the DAC board (if there is one), to send to the recorder.

I'm guessing since none of us have seen it before (maybe John has seen it), you won't find documentation on it. You may have to create your own.

Congratulations on finding a true mystery for us!

Michael

P.S. Thank you for the photo-it's worth more than 1,000 words!

[you795a]

That's what I'm thinking as well. The yellow and green wires would go to the amplifier channels. Yellow and green wires were/are commonly used as speaker wires inside the Allens. The Tape Play box could be for the Y-adapter cables before the amps.

[phisch2]

The black wire is connected to the 12V power supply ground. The Allen tech did say the amps were not original so maybe the tape adapter was disconnected when the amps were replaced.

[Admin]

I was puzzled by the fact that the Tape Record adaptor had outputs, but no shielded signal inputs, but if the wires were connected to the amplifier speaker terminals, that would make sense. My guess is that the box simply contains a passive resistor network, that along with pots, attenuates the speaker output level of the amps to something suitable for a tape recorder input.

This solution of taking the speaker output and attenuating it is a simpler solution to the problem of interfacing MOS organs to other audio equipment. No need for active line amps, attenuator do-dads, and preamps. In fact, the Allen reverb mixer on my MOS-2 derives its input from the speaker outputs of six amplifier channels.

[John Vanderlee]

I also noted a machine screw with washers on the top of the "tape" box. Could there be a relay inside? And if so for what purpose? I'd take the box off, and look inside.

[you795a]

I wouldn't think that there would be a relay inside because I don't see any voltage wires to activate the coil. I'd be curious as well, I'd be opening it up myself.

[John Vanderlee]

I was thinking about the function of those wires attached. Again, a peek inside might tell a lot.

[phisch2]

I will try to open the adapters tomorrow and take pics of what's inside. Thanks to all for the ideas so far!

[Admin]

There's three wires going in for two outputs. As there are two outputs, and no other inputs visible in the photo, I have to conclude that the wires are ground and two inputs. A relay would only make sense if there were other inputs to the box or if there were a minimum of four wires going into the box- two for the coil and two for the switch contacts.

[myorgan]

Before you open the boxes, everyone take a look at the photos in this thread: https://organforum.com/forums/forum/...ick-allen-705d. The very first photo posted, has both of these boxes on a MOS-2 organ amplifier rack, which is currently available (the organ, that is). If you look at the photo, you can readily see that the wires in question go down in the direction of the amplifiers, however, not far enough to know for sure. Perhaps member, 74corvette could help us with this mystery?

Let me take a look at his posts to see if there are any further photos that might help. Meanwhile, check it out, as well as his other posts.

Michael

[myorgan]

A MUTEREL is a mute relay. If the amplifiers' signal turn on when the organ does, there will be a loud "BOOM" from the speakers that would principally affect the woofers. A mute relay delays the turn-on of the amplifiers' audio channels until the rest of the organ has turned on.

A better explanation is here: Mutes audio at turn-on and turn-off to prevent loud thumps. Operated by a delay circuit located inside the AC distribution box on most organs.

Michael

[Admin]

MUTEREL = mute relay. Mutes the audio when powering on and off to prevent thumps.

Let's have look inside the box to avoid further conjecture.

[myorgan]

Awwww, c'mon Admin. We're having so much fun guessing from afar!;-)

Michael

[phisch2]

Here are two pics of the insides of the "Tape record" adapter. Haven't opened up the tape play adapter.

[you795a]

It looks like it takes amplifier levels down to a line level. Used for recording or older style PA system. The other box is probably the same except that the green and yellow wires would probably connect to the amplifier channels.

[myorgan]

Now we know for sure what they are there for and how they work. My only concern now is the extra metal pieces at the bottom of your first picture on your work surface.

Michael