Allen 1800 (1500)(905-0086-? Capture Memory Power supplies

[Dave Rivers]

I'm looking for 2 Allen MOS-I (I think) Capture Memory Power supplies.

This is for my organ rebuild (documented on vpoproj.wordpress.com - pictures there.)

Most everything was stripped from this organ, but I'm hoping to piece
together enough to get a Zuma-group stop controller working to use the
existing draw knobs, etc...

The console has two DM-3 boards in it (156+stops) so I think I need
2 power supplies.

Can anyone verify that at 905-0086-x is what I need? And, I'm hoping
someone can point to a source for a couple...

- Many thanks -
- Dave Rivers -

[circa1949]

That's quite a project you've taken on there.
I must say you were damn lucky to be given that console - and by an Allen installer no less! Hopefully they don't have their territory yanked away from them LOL. As you quipped, the company is not in the business of charity and certainly doesn't go out their way to make life easy for 2nd hand purchasers of their organs.
Continue to ask around about the capture power supply issue. IIRC the very first Allens with moving stops in the 60s & early 70s used magnets from a 3rd party supplier. I can't believe the voltage and pulse standards evolved to be so wildly different after that, and there could be an advantage to buying an "open market" power supply from someone like Peterson instead of going through the Allen beg-a-dealer/wait for months on ebay rigmarole. It isn't really an Allen organ anymore, it's an Allen console. Someone like Petersen might have reversed engineered however Allens worked (certainly no patents are still valid from the 70s) and could supply you with something that would function correctly. If nothing else a change to a few rectifiers and voltage regulators could change a +30V rail to a -30V rail. (vaguest memory of that being one non-standard thing about Allen's capture system - the polarity of the magnets. Jbird?)

[John Kinkennon]

Wow, Dave. I wish I had that console! I've added MIDI to several Allen organs including two draw knob consoles. I had to reverse engineer the Allen design with no schematics other than for the power supplies you mention. Please check my website and contact me if you want to exchange info. The manuals will be 11x6 matrix designs. The pedals may be either bus or matrix depending on the model. The expression pedals are best converted to operate a potentiometer -- much easier than messing with the Allen LDR outputs. I've got a MIDI encoder/decoder that handles 4 keyboards, pistons, expression pedals, and stops. You could have the board(s) fabricated yourself if you like. Nice blog -- good luck! Contact info on my website.

[Admin]

Someone like Petersen might have reversed engineered however Allens worked (certainly no patents are still valid from the 70s) and could supply you with something that would function correctly. If nothing else a change to a few rectifiers and voltage regulators could change a +30V rail to a -30V rail. (vaguest memory of that being one non-standard thing about Allen's capture system - the polarity of the magnets. Jbird?)

It isn't an issue of supplying voltage to the magnets, it's about Allen's implementation and utilizing the existing driver logic circuitry that's present on each stop assembly. In this system Allen pulses all the stops in a division when a combination is changed, not the just the stops that are changing state. A logic signal to each of the stop assemblies steers the pulse to the correct magnet.

Certainly, an off-the-shelf third party system could be used, but not without extensive rewiring, and it's likely to cost much more than a used Allen original.

[Horseshoe_or]

The folks at Harrison Labs are a good source of information.

[circa1949]

"In this system Allen pulses all the stops in a division when a combination is changed, not the just the stops that are changing state. A logic signal to each of the stop assemblies steers the pulse to the correct magnet."

Thanks for clarifying but I knew the way it worked. My question was just whether any other system works in a similar way. Ultimately, logic IS logic. It's just the state of a circuit. Maybe some pipe console systems use +5V to ground, some use -5V to ground, and a vendor allows their power supply to switch to either standard. Compared to other things one might want to reverse engineer in an old Allen console like the key matrices, it seems relatively simple to me. Allen's after market support policies are not written in stone tablets. They could decide at some point the future they won't sell one of their power supplies to support a TG-less console; and waiting for ebay is, well, waiting for ebay. If there's some way to move away from depending on an Allen part, it seems like a good idea for something like a large power supply that isn't known for having an indefinite lifespan.

[Admin]

The folks at Harrison Labs are a good source of information.

Harrison's organ midi products are designed to interface to the Allen's existing electronics. OP does not have them.

[Dave Rivers]

Many thanks for all the replies!

Does anyone have a source for these power supplies? I've started calling around to various Allen distributers to see what's available...

- Thanks -
- Dave Rivers -

[myorgan]

Can anyone verify that at 905-0086-x is what I need? And, I'm hoping someone can point to a source for a couple...

Dave,

I wish I could verify the power supply part number for you, but my organs are all later. However, I have seen one recently on *Bay (in the last month). At first, I thought this was what you were looking for, but realized it was a Card Reader Power Supply instead of a Capture Power Supply.

Would this one work? http://www.--------/itm/Allen-Electr...YAAOSwAKxWWSZP. Even though the listing has ended, perhaps you could contact the seller.

I will keep looking, though. Welcome to the Forum!

Michael

P.S. The Capture Power Supply I saw on *Bay was this: http://www.--------/itm/Allen-Electr...YAAOSwAKxWWSZP.

[tucsondave]

The DM boards used the 905-0086-x capture supplies. They had several variations but all functioned the same.
And yes you will need two.

td

[jbird604]

Yes, that is the part number for the DM capture supply. There were several revisions of it, but they all work the same way. Since your boards are DM-3 (and not just plain DM or DM-2), it would have had a later version of the supply, which might also be the easiest type to find, since the DM-3 system was the one that Allen used over a long period of time.

All the info that's been shared here looks correct to me. It would be a shame to have to strip out the DM system from the console. As has been said, the system is different from most anything else, and you would have to radically re-wire and/or change out the drawknobs to make it work with an aftermarket system. And the DM system works beautifully and is based on a very clever concept.

Almost all Allen organs (except basic models with non-moving stops) built after 1975 and before about 1988 or so will have DM capture (meaning DM, DM-2, or DM-3). You might have to buy a couple of MOS-1 organs to get your supplies. Given the present state of the market, it's not unusual to see them offered for free or very little money. Just be sure to get them with DM-3 capture, and not sequential capture, which will have no parts you can use. You could then sell off the rest of the boards (or keep them for spares) and eventually sell the consoles, pedals, and other parts to other project builders.

It would be best if you got organs with DM-3, as opposed to DM or DM-2, but I think the supplies would be almost identical in the DM and DM-2 system. I seem to recall that there is a 5 volt ouput on some versions of the supply and not others. But I'm sure that any organ with DM-3 will have a supply in it that will work for your setup.

Too bad that you will have to sacrifice two smaller Allen organs to make your system work, but the reality is that many old organs are just gathering dust these days, if not actually going to the landfill. And you will be preserving and enlarging a very wonderful console with which to make great music. Good luck!

[indianajo]

I can't imagine the prospect of begging for, then moving 2 or 3 dead AGO pedal church organs to pick up a working power supply. One with overaged capacitors that will probably blow something in the next 5 years anyway. Old AGO allens go about $1000 around here , the dealers have the seminary student parent's by the hook. It took me 5 years to find a $100 Schober AGO pedal organ and $220 to move it 70 miles home. A blown tire on the first rental truck necessitated a repeat trip and turned this into a 3 day ordeal. If organ dollies are not for rent in your location, it is not a 30 minute job to load one.
Among the arcane secrets Allen kept to itself, power supply design is not one. They built their power supplies just like everybody else before switchers became cheap about 1985. I just redesigned and activated the defective schober power supply for about $20 in parts.
Unless there is a vile odor about the supply, there is probably a $.50 part blown, plus possibly a couple of $5 leaky capacitors. The vile odor might come from a burned transformer, which are about $30-80 but not impossible to replace either. PS parts are commonly available at mail order houses like newark, digikey, mouser, allied.
You could remove the supply and take to a local mitatech for repair. Or you could buy a $30 DVM a $40 soldering iron and about $20 more total tools, read a book, and do it yourself. I started the diy route when I was 14 on car radios. There was no internet then.
Buy Electron Devices, the Electron Flow Version by Thomas Floyd if you want to learn about how transformer power supplies were designed and put together. i picked up the 2nd edition a Goodwill for $2. Or a similar text book from the second year electronics course at your local community college or trade school. Look for leaky capacitors, plus something blown right after the transformer. Possibly a rectifier, resistor, or fuse. Another likely suspect is the voltage regulator IC after the first rank of capacitors and before the second. And after it is working, change out all the electrolytic capacitors, Allen did not buy the epoxy sealed forever variety, if the 301 I repaired is any indication.
Moving organs to the dump, what an expensive and difficult practice.
A switcher supply without a transformer, they are a bit more difficult to draw out the schematic diagram, and a bit dangerous on the front end. In that case I'd be tempted to figure out what voltages come out, then replace it. The same suppliers above sell them, or these supplies are a bit more profitable buying on the overseas ebay market. If +5 and +- 12 are the voltages required, the PCAT ATX computer supplies recommended in other threads are incredibly cheap at $24 plus freight. Capture actions tend to have a 24 v supply to move the solenoids, so I would imagine you might need one of those, or the 27 mentioned on previous threads about the old MOS capture actions. The pipe organ I worked on with a defective Petersen capture action supply supplied 24 v at about 10 amp.

[jbird604]

I-Jo, while I don't disagree that such a power supply COULD be built, it's not as simple as you might think. (Note that our OP here does not have the original supplies, as the console he bought was missing the two units, so repair is not an option. He has the DM-3 boards and the rest of the capture system, just needs the original supplies.)

The DM capture supply is not just a simple power supply, but an elaborate and complex part of the capture action itself. While at its root is is just a very high-current source for DC at about 45 volts, there is a complicated logic-controlled set of outputs that are essential to the working of the DM system.

Each supply unit has four "N" terminals which are linked to the DM board. Each "N" terminal corresponds to one division of the organ -- swell, great, choir, pedal. Whenever a piston is pressed, the DM board sends a triggering signal to the "N" terminal corresponding to the division in which the piston is located (or all four in the case of a general piston). This trigger signal then goes through a logic circuit that tells the power supply which of the output lines -- labeled "SP" or "CP" on the supply unit -- are to receive a quick 45 volt pulse.

Each "SP" or "CP" output line is driven by a high-current transistor switch so that the voltage can be quickly turned on and off.

These "SP" output lines go to the coils of the stop tabs or drawknobs, one SP line for each division of the organ, and the single CP line for couplers and other controls only addressable by the general pistons.

When the DM board sends the signal to trigger a quick pulse to the appropriate set of tab or knob magnets, it also sends a control signal directly to each tab or knob individually. This is a "steering" signal which is either "high" or "low" to tell the tab or knob whether the pulse is intended for the "on" coil or the "off" coil. Some transistors and diodes on the little PC board piggybacked on each tab or knob then direct that pulse to the correct coil. All this happens in a small fraction of a second.

So, you can see that the DM capture supply is a rather complicated piece of equipment that you can't just put together using off the shelf parts from here and there. That is why I suggested that junking out a couple of smaller Allen MOS organs would be a good way to get his hands on two of these. You can probably find a whole organ for less money than the cost of this one supply.

I understand your frustration, with AGO organs being in such demand in your area that the prices for used ones are quite high. That is not the case here, where MOS organs are sometimes offered for next to nothing if not free. Of course, he is looking for a very specific power supply and not just any old Allen will have the right one.

These power supplies were built like a tank and except for the very large storage capacitor, which might eventually succumb to the ravages of age, most everything in there was designed to last until the rapture. The first of these out the door are now 40 years old, and I have yet to replace anything in one of them other than a driver transistor or two for a pulse circuit.

BTW, I just checked the Allen parts catalog, and yes, the supply can still be bought, but it is indeed pricey, and I've seen plenty of MOS organs go for less money. I also see that the same supply is used not only for all DM capture systems, but for the USCP-2 system as well. So even the late ADC models would have the same supply, making his range of choices for an organ to junk out even larger.

[circa1949]

These power supplies were built like a tank and except for the very large storage capacitor, which might eventually succumb to the ravages of age, most everything in there was designed to last until the rapture.

John, I got a chuckle out of this.
Thanks for the great write-up.
Just to play devil's advocate though, has it been proven that any other pulse power supply for capture actions won't work? I suppose very few people have been willing to risk their organ's stopkey or drawknob circuits to find out. But it seems to me that its not outside the realm of possibility that for example, the steering circuit logic lasts as long as the button is pressed...which could be hundreds of milliseconds...while the main pulse(s) are precisely timed for say 50 milliseconds after the piston press. In that case, couldn't any other pulse power supply with the appropriate voltage drive the stop movement? Allen presumably split the pulses per division not to make their system incompatible, but to preserve the life of the power supply. Right? Why would it matter if an aftermarket supply for a pipe organ, in fact, triggered all of the divisions together? But maybe not: maybe if the 45V arrives at a division that isn't "prepared" by the steering circuit, it could cause problems. It just seems to me that with all of the other things people figure out and repair from pin ball machines to, well, various other electronic musical instruments, someone could hook up a bunch of signal analyzers, o-scopes or whatever tool(s) are appropriate and really trace out all of the pulse trains and timings and determine whether or not someone is truly locked into the Allen part or not. Or, alternately, reverse engineer the Allen supply itself. Sounds to me like it's a typical high current supply but with 4 pulsed output rails triggered by an input signal. Shouldn't be too hard for someone who's already into ham radio or electronics.

[jbird604]

True. The capture supply could be reverse engineered by a diligent builder. An ordinary transformer steps down the 120 volt AC to a lower voltage, it's rectified by a bridge, then stored in a large capacitor until needed. The outputs are switched by rather straightforward transistor circuitry with some big power output transistors as actual switches. There is no timing circuitry in the supply itself, as the timing of the pulse is controlled by the DM board. In other words, the DM board grounds one or more "N" lines for a specified number of milliseconds, and this quick grounding of each line simply opens the corresponding transistor and passes the current out the corresponding "SP" terminal until the grounding ceases.

A little more complicated, but still straightforward, is the logic circuit that senses when more than one "N" line is being grounded at the same time, which tells the supply that a general piston has been pressed, as opposed to a divisional piston, which results in the DM board grounding just one "N" line. When this little logic circuit detects two "N" lines going to ground, it triggers the "CP" output to fire, which, as I stated, is the line that powers the coupler tabs, since they operate only with general pistons and not divisionals.

There is no separation in time among the four or five pulses, far as I know. The supply is capable of outputting enough current to drive all the magnets at the same instant (unlike the old sequential system).

Also, the DM board itself sends the high/low steering signal to the tabs or knobs, so that function is irrelevant to the power supply.

The only other thing inside the capture supply is a 5 volt regulated supply that is used by the DM board for some other purpose.

So, yes, a well-equipped and sharp tech or engineer could build one of these from scratch. But if you add up the time that would be required to collect all the parts, design and fabricate a proper chassis and cage for this, then build it up with project boards or else have a custom pc board made for the electronic parts, along with the cost of the components themselves, I think Allen's rather high price is in fact justified. And getting one from a scrapped out MOS Allen is even better!