Allen Board Identification

[myorgan]

Folks,

Does anyone know what a DPDT Relay does in an Allen Organ (#904-5732)? So far, I have seen it on an ADC-6000, ADC-5400, and MADC-1100. However, I haven't found it on my ADC-4300.

What is it and what does it do?

Michael

[toodles]

In the MADC-1100 it is used to turn on/off the presence projector speakers. For the other models, I am not sure. It could be used to turn on/off remote presence projectors , or any other general purpose switching functions.

What tabs (apart from voices) do the ADC-6000 and 5400 have that the 4300 does not have? En chamade speakers? Presence projector on/off, chimes (for external real chimes)?

It is a DPDT relay with no circuitry except for an anti-flyback diode that operates on 12 VDC. If the relay coil itself is low enough in current it could be operated by one of the remote outputs (REMOUT). You can find out the coil current if the relay manufacturer is marked on the device and then do an internet search.

[myorgan]

What tabs (apart from voices) do the ADC-6000 and 5400 have that the 4300 does not have? En chamade speakers? Presence projector on/off, chimes (for external real chimes)?

Toodles,

Thanks for the reply. Let's see what each organ has:

Feature	ADC-4300	ADC-5400	ADC-6000
Antiphonal Relays	No	Yes	No
PP On/Off	No	No	No
Brass Chorus	No	Yes	No
Bass Coupler	Yes	No	No
External Chimes	No	No	No

Needless to say, I'm stumped. I did try to trace the wires on the photos I've taken (the organs are not available to me right now), and one appeared to be connected to one of the 4 small, square REM connections at the bottom of the board. It also appeared to be connected to one of the 4 REM Outputs on the short edge of the same board as well. Since I don't have REM charts for the organ I traced, I was unable to discover the function of either REM connection.

I'll have to wait until I can get a REM chart for one of the organs in question to trace what they do. Maybe that will answer my question. Thanks so much for the response, Toodles!

Michael

[toodles]

On the 5400 it is probably related to the Brass Chorus--if I recall correctly that function requires some input to the multiplexer board that the REMOUT switches. On the 6000--perhaps an option that is prepared for, but not installed?

JBird probably has the REMOUTS for these organs, so maybe a PM to him?

[jbird604]

I do know that there is a REM output on some models that is dedicated to the Brass Choir. But I have no idea why the organ requires an external relay in order to activate the Brass Choir stop. You'd think it was just a stop like any other, activated by the USCM stop map. But there is something spooky about the way the Brass Choir works that requires the relay. The tech site doesn't explain this and I haven't seen it spelled out in any service manuals either.

On certain models, the relay is used to produce "all swells to swell" by switching the connections to the expression cells. On some models, it enables "great/pedal unenclosed" by breaking the connection to the expression cell on that division's USCM input. On a few MDS models it serves to boost the volume of the channel that contains the Festival Trumpet by jumpering around a series resistor in the audio path. In that application, the REM output that trips the relay is enabled only when the FT stop is drawn by itself. If any other choir stops are drawn with it, the relay is not actuated and the FT stop becomes just a plain trumpet. This trick is not used in all MDS models with FT, but I have seen it in some of them.

So it's just a general purpose device that is used wherever a relay function is required to make something happen that isn't a cage function. To see what it does in a given model you'd have to trace the wiring attached to it and see where it goes. For some reason, the tech site has little or no info about this.

[myorgan]

After reading both your posts, my best guess is that the relay does do different things in different organs, depending on the task it's assigned. In one organ, I think it is the relay for Main Organ Off, while in another organ it is Great/Pedal Unenclosed, and yet in another organ, it is connected to the Brass Choir stop and activates that relay. WOW!!! Too bad there isn't more documentation for that particular card!

My only confusion now is that in one organ, it is connected to 15+/-, while the other is 12+/-. I'm sure the power requirement needs to be there in different organs, but does the relay really care whether it is 15 or 12? Maybe one is more prone to burnout if it is on the higher power?

Thanks so much for your input. It makes me wish I had access to Allen's documentation site, but I know that will NEVER happen--even since I have many of their older organs! Not even a service manual to be found!:'(

Michael

[toodles]

The average relay is pretty tolerant of the coil voltage, energizing on as little as 80% of its rated voltage and permitting 10 to 20% overvoltage, so you don't need to worry about burning out the coil with excess voltage. I'm sure the engineers at Allen reviewed the coil specifications before choosing to operate a specific relay on different voltages to be sure there would be no damage.

It's not like a light bulb that burns out much quicker on a higher than normal voltage. A higher voltage on a coil will generate more heat, and whether or not that causes damage has to do with insulation ratings and adhesive breakdown temperatures.

Then there are so-called "sensitive" relays with a very high coil resistance that are specifically intended to work on very little current, and have extremely wide voltage range--maybe 70% to 190% of rated voltage.