Allen ADC-5300-DK Crescendo and audio path wiring questions

[cpistel]

Hi Guys,

After playing a new to me ADC5300 at home for a couple of years, I've decided to attack some of the issues the organ has to bring it back to what it once was. I have a couple of questions that I hope the forum can assist me with:

1. There are a couple of wires broken off of the crescendo pedal. An anyone offer a picture or description of which color wire goes where on the encoder/switch/whatever the mechanical to electrical converter is called?

2. I have Allen's early external sound module that came with the organ. It's audio path seems to be via the swell speakers and swell audio path. However, one channel of it seems to be much stronger than the other. Additionally, the reverb, when engaged, will, after a short delay, start to create a positive feedback loop. Looking around inside the console, I question the hookup of the external module. I'd like to get back to the audio connections from the module and the connections to the mixer and reverb as designed by the factory. Does anyone have any diagrams of how the audio path should be connected from the cage, thru the mixer and ADR4 and out to the amps. How should the external expander be connected into this? I think I'd really enjoy having some reverb in my tiny little room. The organ also has extra amps installed but no speakers for them and no connections to them that I can see. It also came with what appeared to be a speaker to line level converter that was not attached to anything. Thus, I think the organ audio path has been tinkered with and I would really like to untinker it.

I have a pedal channel that recently has become intermittently quiet, loud and crackly or normal. I need to get into the organ to hopefully exercise some pots and clear this up. I would like to tackle my other gripes at the same time. All suggestions/ info gladly excepted.

Thanks,
Chris

[myorgan]

I have a pedal channel that recently has become intermittently quiet, loud and crackly or normal. I need to get into the organ to hopefully exercise some opts and clear this up.

Craig,

Congratulations on getting such a nice organ. Regarding the Pedal, my guess is that one of the two Pedal channels has an issue with the Gain pot on the board inside the cage. See if you can isolate it to a certain group of stops, and that will help determine which channel/chard is the issue. It's a simple fix, by just exercising the pot, but it has to be the right one or you could mess things up.

There are a couple of wires broken off of the crescendo pedal. An anyone offer a picture or description of which color wire goes where on the encoder/switch/whatever the mechanical to electrical converter is called?

If a couple of wires are broken off the crescendo pedal, my guess is you could match the colors of the wires to where they used to attach. If the wires are sequential, I'm not sure it really matters which is connected where as long as they are adjacent to each other. If they are from far apart, the order they are activated becomes more important. Let me do some checking to see what I can find about the crescendo order on an ADC-5300.

Others will weigh in with more expert advice.

Michael

[cpistel]

Thanks, I really like it. Unfortunately the crescendo wires broke right at the solder joints so every color is silver at that point. :-( and it's not apparent from the wire bundle which went where. I assume its some sort of encoder (BCD, grey code, etc) as there's only a handful of wires involved. I could always try a couple of combinations but if there's an easy answer I'd rather do that than experiment.

Craig,

Congratulations on getting such a nice organ. Regarding the Pedal, my guess is that one of the two Pedal channels has an issue with the Gain pot on the board inside the cage. See if you can isolate it to a certain group of stops, and that will help determine which channel/chard is the issue. It's a simple fix, by just exercising the pot, but it has to be the right one or you could mess things up.

If a couple of wires are broken off the crescendo pedal, my guess is you could match the colors of the wires to where they used to attach. If the wires are sequential, I'm not sure it really matters which is connected where as long as they are adjacent to each other. If they are from far apart, the order they are activated becomes more important. Let me do some checking to see what I can find about the crescendo order on an ADC-5300.

Others will weigh in with more expert advice.

Michael
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[AllenAnalog]

As another proud owner of an ADC-5300, I have tried to learn everything I can about the instrument to keep it running for a long time. When I first got it I took many photos of the console interior to document how it was wired. Alas, my photo of the swell and crescendo pedals is from the wrong angle for a perfect look at the wires. But by cropping that picture I think you can see the wire colors.

There are six wires connected to the switch. They connect back to J235 on the USCM console multiplexer board. To me it looks like they have the following colors, from the back to the front of the organ: red, yellow, white, green, blue, black.



I can't help you with the external sound module connections but in the standard factory configuration, the six cage outputs go to jacks on the left side of the USRM-3 mixer and the amps connect to jacks on the right side. A cable plugged into J481 on the right side goes to the ADR-4 and the two outputs from the ADR-4 go to J479 and J559.

Since the USRM-3 has seven audio inputs and outputs, it is possible that your external sound module, if it has a monophonic output, was connected to the normally unused channel 7 input jack on the mixer board. Then the channel 7 output jack would be connected to an additional amplifier and speaker. On my mixer the channel 7 input jack has a shorting plug in it to eliminate any electrical noise from that unused input.

Be aware that the expression for all six standard organ channels is done in the card cage, before the reverb mixer board. So any audio signal connected to channel 7 will be at a constant level, not affected by the swell shoe position.

USRM3_Labels.pdf

[cpistel]

Thanks Larry,

I may ask for a few more pictures. I'm not near the organ right now but I recall a USEM-2 and another board that I was wondering about. I appreciate the pic of the crescendo encoder. That's going to be a great help

[AllenAnalog]

Steve, not sure if you need to start your own thread for your instrument if it has some special factory wiring with extra hookups. I'm reasonably certain that Allen never shipped organs with black electrical tape on lose wires. All of the extra wires in my instrument are carefully folded back in their cable bundle and not connected at either end. I'm guessing that a previous owner or a service technician made changes to or disabled your crescendo system.

As far as I know, and someone can correct me if I am wrong, the ADC model line crescendo pedal has always used a switch that generates a "Gray Code" to send position information to P244 on the USCM-1 (or USCM-2 in larger organs) console multiplexer board. There is no potentiometer and there are no duplicate connections. There are 20 individual steps in the ADC crescendo sequence so you need more than 3 wires to encode the position of the switch using the Gray ("reflected binary") coding system.

If the switch was disconnected because it was noisy as it moved through the steps, there are multiple old threads on this forum about that, along with suggestions for flushing out and cleaning the contacts. Here are a couple of threads covering that process:

https://www.organforum.com/forums/showthread.php?47087-Allen-Crescendo-Switch-Possible&highlight=allen+crescendo+switch

https://www.organforum.com/forums/showthread.php?49937-Crescendo-Expression-Pedal&highlight=allen+crescendo+switch+cleaner

The expression pedals use a light bulb, powered through an adjustable resistor, a shutter, and a light-dependent resistor to control the volume. So again, no potentiometer. Allen has used this patented system on swell pedals for decades to eliminate scratching noises from aging and worn potentiometers.

[jbird604]

The presence of the USEM-2 board indicates that the organ was prepared to receive more audio channels, probably incoming audio from a MIDI expander. The USEM is a small external mixer that is generally used in ADC and MDS models to provide some additional line level audio inputs, which are then mixed into some of the existing channels. Perhaps the USEM in your organ is installed in the swell audio path (channels 1 & 2?) and some of the extra inputs on it are dedicated to receiving the MIDI box's audio. That would explain why the Expander's sound is heard only in the swell speakers.

Somewhere I have a functional diagram of one version of the USEM, but not sure it's exactly the same as yours. Some versions of it actually had provisions for connecting some external expression cells, so that the channels passing through it could receive expression. Of course, you might not be able to do that in your case, because the swell channels are already under expression within the cage.

[davidecasteel]

For any reasonable number of binary digits (2 or more), there are multiple Grey Codes that can be set up and still be re-entrant. I'm assuming that any of them would function in a Crescendo Pedal, but only one of them will give the right order to the stops.

[cpistel]

Thank you to all the people that weighed in.

I now have a working crescendo pedal and working reverb and was able to get the expander hooked up and playing. I haven't got it to express, although the extra photocells are on my swell pedal and connected to the USEM2. I actually think I prefer the module not express, so I'm quite happy with the setup. It is also great to now know I have another set of inputs available for an additional sound module should I ever feel the need. As usual, this forum have saved me tremendous amounts of time and frustration.
Thanks again, and Happy New Year!
Chris

[AllenAnalog]

That's great news Chris. You are now officially a happy member of the ADC-5300 owner's club. When you have a moment could you post a photo of your USEM-2 board?

[cpistel]

Appologies for the focus. This is the only one I have with me. If I find a better one, I will post it in the future. I am still fighting with getting the pedals balanced with the rest of the organ so I might be back inside again soon and I can take a better one.