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Allen TC-4 Project

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  • Silken Path
    replied
    Curious - sat down at the organ this evening and it has tremolo. Made sure I hadn't activated the gyro, and then I got up and looked at the Whind machine, and surely enough, it is ticking right along... I both love it and hate it when something starts working without explanation. That which starteth can quiteth again. We shall see.

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  • Silken Path
    commented on 's reply
    Well, the seller has issued a full refund on the Whind machine. It took over a year for one of these to show up. At least I have one that can be repaired.

  • Silken Path
    commented on 's reply
    Hey Larry - the picture of the rack of that 3MAN custom... or your TC-8 pictures, actually gave me the idea. The TC-4 has been SO trouble-free, all things considered. Part of me suggests that I shouldn't MESS with it, but that's a tiny, mostly mute part of me. I wanted Whind machine #2 so I could work on #1 and fix the tremolo. But... #2 is actually a newer model. It's the LAST newer model that Allen made, in fact, but John B. told me that the early MOS machines had a similar circuit. So the tremolo on #2 just barely works and I can't hear it at all. So the seller agreed to send me another one... and #3 is out there... somewhere.

    I would like to have a three manual analog, but two rows of tab stops is not exactly beautiful. I like the TCs because there's plenty of technical talent here for virtually anything that goes wrong with it. This is the shining moment in time that a common person can own, play, and maintain a magnificent machine.

    I could see a TC-8 here. It's just more of more of.

    #3, by the way, is another one of the compact models.

  • AllenAnalog
    commented on 's reply
    Sorry to hear about that mix up. I hope the seller has told the inadvertent recipient of the Whind machine that he will pay freight to ship it to you.

    The photos I've seen of older large instruments showed labels on multiple Whind machine chassis in the rack that marked which division they supported so I don't think you are considering anything that wasn't somewhat standard.

  • Silken Path
    replied
    Yikes, the replacement Whind machine is lost somewhere out there... I got a well-used Dell wireless mouse instead of it, and somewhere somebody who needed a mouse is looking at a Whind machine and wondering just what the heck it is. So this is a wee problem. Don't the rules say that if you get something that you didn't order, you can keep it (except for other people's money accidentally deposited in your bank account). So what if that other person, who has the Whind machine, doesn't WANT to send it back?

    Anyway, the thought occurs to me that I could put one Whind machine on each manual and have per manual control of tremolo and Whind... I think I know where it comes in, too. It's the big wire on the springs at the rear of the keys...

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  • AllenAnalog
    commented on 's reply
    Rather than further hijacking your TC-4 thread, I've started a new one since GG took over this one for me and it got a bit long.

    https://organforum.com/forums/forum/...alog-era-stuff
    Last edited by AllenAnalog; 10-22-2020, 09:22 PM.

  • Silken Path
    replied
    Hi, Allen - This thread has wandered all over the place, so you're welcome, of course.

    So I have two different types of Whind machines now. The newer one is more compact and has one power cord. Allen made it smaller, I guess, to put in the bottom of the TC models - it fits perfectly, at least in those models that don't have four generators. Since the smaller unit is basically the same thing - just with the three circuit boards in the same case - I now prefer the newer model. It's a 900-0171, exactly what Toodles provided.

    I still haven't permanently set up the flapper-equipped gyro that I bought from John B. My plan is to add another gyro for the diapasons, and I'd like to have the deluxe one like I have now. I mentioned somewhere back in the thread that I tried the reeds through the gyro + flapper instead of the stationary horns-tweeter-woofer, tilted-front speaker I have. I did NOT like the sound of the reeds through the gyro, and unfortunately, I did not like the sound of the diapasons running in the gyro, either - it was much too fast to be a tremolo. I DO like the sound of the reeds through the flappers, though.

    I have moved the speakers for the Allen. I have a 200 sq. ft. "office" attached to a 550 sq. ft. garage that the organ is in. The office has two doors that open into the garage, and I have the flutes stack and the diapason/reeds stack facing different doors. This has made the organ so much more pleasant to play. This desk I'm sitting at is between these stacks... They're sitting on half-ton plastic dollies from Harbor Freight, and I've shored them up with 2x4s to keep them from tumbling over. I'm still amazed at the sheer sound pressure that 50 W x 3 can make through these old-fashioned monster speakers, and I have all the amps all the way down.

    And here's a thought from nowhere. When I select an organ sound on my Rodgers, it turns on the Leslie simulation. I have tried running organ sounds from my little Juno synth through my Neo Ventilator II, and if I slow it down a lot and add some fuzz (overdrive), even the classic organ sounds on the Juno are better. "The pipe organ voice of the electronic organ," or something like that. So what would that electronic method for the reeds be?

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  • AllenAnalog
    replied
    I'll be following your progress. The RMW/Tremolo unit in my theater organ was disconnected when I bought it. I bought a spare unit on ebay several years ago but have never tried to hook either one up. Good to have the complete document from Toodles and the Mouser part number in case my neon is dead.

    I should probably start a new thread for this but since there are only a handful of us analog owners on here any more I'll momentarily hijack your epic thread. The electronic trem was only used for the reeds on my organ. The flutes and strings have gyrophonic projectors for the trems. I have enough parts to build a matching gyro cabinet for my reed channel but somewhere I read that it did not sound good so they used the electronic method for the reeds.

    That big Allen analog out in Sacramento had the small motor-driven flappers in front of horns for the reed channels. I think you mentioned you have them too. Any thoughts on the differences between the electronic, gyro and flapper tremulant quality?

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  • Silken Path
    commented on 's reply
    Turns out that I did not stop... The TC-4 is still as of today my main organ.

  • Silken Path
    replied
    Well, I got the power cord on and installed the Zener across the inside of the 9-pin. The tremolo barely wiggles the meter or flashes the light on the organ. The seller is honoring the agreement we had and is sending me another one. (I told him I wanted the one in the ad this time.) The noise circuit and thus the Whind seem to be working. I tried some of the obvious things like squirting/exercising the pots and connectors. At least the B+ (keying) is working and tremolo is *trying* to work.

    I'm going to stand by until the other unit gets here. The organ remains playable.
    Last edited by Silken Path; 10-21-2020, 11:40 PM.

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  • Silken Path
    replied
    Thanks. I've been reading about them. Ordered two and a spare. And that explains why I was having so much trouble searching for it. I was entering "IN4744 zener diodes" and it was showing me everything EXCEPT IN4744 diodes. Live and learn is such a booger it's amazing that I've made it this far.

    I'll occupy myself replacing the power cord, which is literally falling apart. It had been in Texas, and I bought it from a charity sales outlet.

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  • toodles
    replied
    That's the correct one. Allen mistakenly used IN instead of 1N in the diode number. There is no "IN" for diodes.

    In the world of noise generators, different methods have been used to generate white noise. The least expensive is probably a selected transistor used with the emitter-base junction reversed biased to cause breakdown; the breakdown creates random noise. A zener diode when used as a regulator (i.e., reverse biased as a diode, but the normal way a zener is used) also generates noise. Rodgers, for a while, used electrolytic capacitors in reverse connection, also causing a breakdown and noise; they used a low voltage to do this, presumably so the capacitors wouldn't explode.

    Finally, an engineer at Thomas organ worked with National Semiconductors on the sly to generate a noise IC--Thomas wanted it for their rhythm percussions, but volume wasn't enough to justify a custom chip. By working with National and letting National sell it as a standard product, Thomas got the needed part, and others could use it as well. Personally, the character of the noise of this IC isn't really "white", as there is a low frequency repetitiveness to the noise--i.e., it tends to sound like a shaky tremulant when used to modulate amplitude. It's good for high frequency noise, though, such as for cymbals. Avoid it for things like random motion.
    Last edited by toodles; 10-09-2020, 06:30 PM.

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  • Silken Path
    replied
    Is this a suitable IN4744? (They stock a lot of this one.)

    https://www.mouser.com/ProductDetail...jeOjc3Cg%3D%3D

    And Brother Toodles, I updated my manual and service bulletins with the pages I didn't have. Thanks again.

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  • Silken Path
    replied
    Thank you. Toodles ! I thought I'd read everything, but I don't have that 1985 service bulletin. (My analog service manual was made up before then.) OK. First I'll see if the seller has this plug-in module and will send it to me, and if not, I'll convert it to a Zener diode. (And put it inside the case.)

    To other readers with Whind supplies, that PDF file that Toodles attached has the RMW pages from the manual AND the associated service bulletins, including the 1985 service bulletin that describes converting it to a Zener diode in place of the neon bulb... or I'll just put the Zener inside the can to preserve the appearance... or put it under the case and leave the can for appearance.

    On the spot again, Sir toodles

    You ARE a handy fellow to have around.
    Last edited by Silken Path; 10-09-2020, 05:38 PM.

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  • toodles
    replied
    You might be able to find a 9-pin socket plug base; if you can, see the attachment for info on replacing the neon lamp with a zener diode, which is Allen's recommendation. See attachment for a lot of details.

    Allen RMW Complete.pdf

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