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Allen 301 C Celeste problem and a cleaning question.

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  • Allen 301 C Celeste problem and a cleaning question.

    I was given this unit and I'm trying to fix it up for a practice organ for someone. Outside of needing a serious cleaning, everything works, except for the Celeste ranks. Actually they work but many notes are way out of tune. Since this is an analog rank I suspect the capacitors have drifted out of tolerance. I'm wondering if I should just "pad" them to the right value or do a wholesale replacement of the frequency-determining caps. It's not that bad, only 37 or so. The trouble is that it is difficult to read the values because of the physical location. Does anyone have access to a schematic of this celeste rank? It starts at C1.
    I am going to add reverb to liven it up a bit by using a stereo reverb unit, However this extra rank makes it 4 channels with each pair getting mixed in at the amplifier inputs. I guess I should pick up the signal inside each of the two amp chassis after they are mixed internally.
    Speaking of cleaning, the cabinet has decades worth of grime and needs some serious cleaning to get it at least presentable. Any ideas on how best to do that and keep the finish?
    Thanks to all in advance!
    John
    Can't play an note but love all things "organ" Responsible for 2/10 Wurli pipe organ, Allen 3160(wife's), Allen LL324, Allen GW319EX, ADC4600, many others. E-organ shop to fund free organ lessons for kids.

  • #2
    Allen's procedure for tuning analog ranks includes selectively replacing or padding the capacitors you mention in order to center (approximately) the tuning adjustment. Allen supplied their technicians with a capacitor kit for the purpose.

    The procedure does not say anything about replacing all of the capacitors, but of course it was written when the capacitors were relatively new and not decades old.

    If the organ were mine, I would replace all of them if they are of an inferior type likely to have drifted significantly or become lossy. Otherwise I would leave them alone and change what is needed in order to carry out the tuning.

    Have you considered that the capacitors are still on-value but that other components in the oscillator circuit have drifted? The most likely culprit is the inductor, but resistors also have an effect on the tuning and may well be off by 20% or more after decades of use. A good multimeter with a capacitor function would quickly rule in or rule out the resistors and capacitors.

    Comment


    • #3
      This is a case where you might want to check the ESR if you have an ESR meter. If not, if you have a signal generator and an oscilloscope you can use that too. You don't need to desolder anything to use either of these two techniques. If the ESR is ok for the capacitors, then I would pad away. If the ESR is off, I would replace them. No sense spending a lot of time working on the circuit, then you have worse troubles because the capacitor shorts. Don60's suggestion of testing the other components makes sense too.

      Usually you start with soap and water on the cabinet, then see how far that gets you! Don't get it sodden, just enough to get the grime off, and some scrubbing with a soft sponge if necessary. If there are glaring problems with the finish after that, then you can think about repairing the finish or refinishing.

      Current: Allen 225 RTC, W. Bell reed organ, Lowrey TGS, Singer upright grand
      Former: Yamaha E3R
      https://www.exercisesincatholicmythology.com

      Comment


      • myorgan
        myorgan
        Super Moderator
        myorgan commented
        Editing a comment
        Forgive my ignorance (read: old age): ESR?

        Michael

      • Larason2
        Larason2
        f Forte
        Larason2 commented
        Editing a comment
        It stands for "Equivalent Series Resistance." Basically, it lets you check if a capacitor is bad. You need some other measure besides capacitance, because a capacitor will read close to it's designed capacitance until almost the second before it shorts. There are other ways to test if a capacitor is still good, but this is the easiest and works most of the time. On the other hand though, this is only for electrolytic capacitors, other types like ceramic basically never fail. As well, capacitors used in an audio signal chain are never very high value, and so are less likely to fail. Once you get to 50 years old though, even ones used in the audio chain should be checked before assumed good!

      • Larason2
        Larason2
        f Forte
        Larason2 commented
        Editing a comment
        If you don't have an economical way to check ESR, you can just assume old electrolytic caps are bad. If they are ceramic caps, I wouldn't worry about them - the problem is probably elsewhere!

    • #4
      I tried padding the freq. determining caps and was able to shift the frequency down, So that means capacitance is lost with age. However if I have to experiment with padding I would need a lot of misc. value caps. Then I might as well order the original values and just replace them. BTW they are the paper/foil types. I found that resistors age better than capacitors.
      Can't play an note but love all things "organ" Responsible for 2/10 Wurli pipe organ, Allen 3160(wife's), Allen LL324, Allen GW319EX, ADC4600, many others. E-organ shop to fund free organ lessons for kids.

      Comment


      • Admin
        Admin
        Administrator
        Admin commented
        Editing a comment
        No. Paper foil capacitors are not electrolytic. They contain no electrolyte. Paper is used as the insulating material.

      • John Vanderlee
        John Vanderlee
        ff Fortissimo
        John Vanderlee commented
        Editing a comment
        Early Paper foil capacitors lose value over time. I agree with Admin, and they are not polarized like electrolytics. Again I'd have to buy a selection of capacitors to do the padding. I'd rather just buy the right values, because it looks like that rank only uses about 6 different values with the little pots making the tuning adjustments within that range. Next time I'll take pictures of the celeste unit.

      • Larason2
        Larason2
        f Forte
        Larason2 commented
        Editing a comment
        Ah, ok. Thanks for the correction!

    • #5
      Murphy's Oil Soap works well for wood (console case & pedalboard), keys, and stop tabs.

      For analog tuning, the cap values are irrelevant. Get the pitch as close as possible with the tuning pot. If you can't get it in tune, just remove or add a tuning cap until it can be tuned with the pot. (Sorry, I can't remember flat or sharp/remove or add.) Allen says to keep any removed caps for future use. I have an old cap kit from Allen in a wooden box, though it has no label.

      Don60 is right about the instructions being written decades ago, but obviously the values drifted back then and fine tuning is done with the pot anyway.

      I have a 301B that I need to get running. I serviced many of them years ago and always liked the analog celeste.

      Comment


      • John Vanderlee
        John Vanderlee
        ff Fortissimo
        John Vanderlee commented
        Editing a comment
        The oscillator is a tank circuit, which means it uses a coil and a capacitor in a feed back loop with a transistor and a few resistors to control the gain (used to be a vacuum tube stage in the older days - hence the zillions of triodes in early Allens). Anyhow, the inductance of the coil and the capacitance value set the frequency. Since the coil is fixed and probably quite stable, it's a drifting capacitor that knocks the tuning out.

    • #6
      I've seen and heard Howard's Feed 'N' Wax will do a good job with restoring finishes that have been abused. I have some of the stains, but haven't used it yet–waiting until all the organs are in the garage first–dealing with -0˚F temperatures lately, so it might be a while.

      Thank you all for posting what I was thinking about–padding the caps. I had just read that in my source of Allen information just 2 days ago in an Allen Service Letter for analog celeste information, but wanted to verify before I posted.

      You guys are a great source of information!

      Michael

      P.S. Thank you Larason2 for defining what ESR is, and how to apply the concept.
      Way too many organs to list, but I do have 5 Allens:
      • MOS-2 Model 505-B / ADC-4300-DK / ADC-5400 / ADC-6000 (Symphony) / ADC-8000DKC
      • Lowrey Heritage (DSO-1)
      • 11 Pump Organs, 1 Pipe Organ & 7 Pianos

      Comment


      • Organkeys Jones
        Organkeys Jones
        p Piano
        Organkeys Jones commented
        Editing a comment
        Yes, some kind of wax or polish would be needed on the wood after cleaning with Murphy's. I've used Old English, but recently bought a can of Restore a Finish, but haven' tried it yet.

    • #7
      I'd love to hear people's actual experience with this products.
      Can't play an note but love all things "organ" Responsible for 2/10 Wurli pipe organ, Allen 3160(wife's), Allen LL324, Allen GW319EX, ADC4600, many others. E-organ shop to fund free organ lessons for kids.

      Comment


      • myorgan
        myorgan
        Super Moderator
        myorgan commented
        Editing a comment
        John,

        I forgot to include the link to their Testimonials: https://www.howardproducts.com/testimonials/

        Sorry about that. They also have videos available on their website, so it might be worth checking out.

        Michael

      • Silken Path
        Silken Path
        ff Fortissimo
        Silken Path commented
        Editing a comment
        If I were the manufacturer of a product, I would pick my testimonials to publish carefully. I would make sure that any additional points covered in comments favored the product.

      • myorgan
        myorgan
        Super Moderator
        myorgan commented
        Editing a comment
        Lamar,

        I just re-read the testimonials, but couldn't find anything negative. To what were you referring?

        Michael

    • #8
      I bought two containers of Restor-a-finish, but I’m yet to use them. I was going to use them for two projects, but reading online and asking for comments here discouraged me from using them. One was refinishing the bench of my Yamaha E3R, the other was my piano. For the Yamaha, I was advised to use a water based finish instead, and it turned out great. For the piano, I’m going to use the technique they recommend for old shellac finishes for Reed organs, since it is from the same time period.

      What I’ve read about the Restor-a-finish is that it doesn’t remove scratches if they are too deep. It also isn’t compatible with some finishes, and so may yield less than desirable results in some cases. I may still use it someday, but I’ll test in an inconspicuous location first!

      Current: Allen 225 RTC, W. Bell reed organ, Lowrey TGS, Singer upright grand
      Former: Yamaha E3R
      https://www.exercisesincatholicmythology.com

      Comment


      • #9
        Just to bring this back on topic, here are pictures of the Celeste generator
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        Attached Files
        Can't play an note but love all things "organ" Responsible for 2/10 Wurli pipe organ, Allen 3160(wife's), Allen LL324, Allen GW319EX, ADC4600, many others. E-organ shop to fund free organ lessons for kids.

        Comment


        • #10
          I know there are people who “hand roll” their own foil and paper caps. It’s not too hard, but it would be time consuming!

          Current: Allen 225 RTC, W. Bell reed organ, Lowrey TGS, Singer upright grand
          Former: Yamaha E3R
          https://www.exercisesincatholicmythology.com

          Comment


          • #11
            Interesting thought but I’m not about to do that. I found a friend of mine has a capacitor decade box. I will borrow that and see if I can pad the values. Then I can purchase caps closest to that.
            Can't play an note but love all things "organ" Responsible for 2/10 Wurli pipe organ, Allen 3160(wife's), Allen LL324, Allen GW319EX, ADC4600, many others. E-organ shop to fund free organ lessons for kids.

            Comment


            • #12
              I do not believe those capacitors are the old "paper" type. They probably use a mylar dielectric and are high-quality, stable components. True waxed-paper capacitors were round and had sealing wax visible at the ends of the cardboard tube. With time, this wax would drip out and make a mess of the surroundings.

              John, you should pick a note that is far out of tune and measure the values of the capacitors with a reliable meter (after removing them from the circuit). Then we will know whether they have drifted or not.

              The photos show a pristine, factory build that has never been modified in the field, so any previous maintenance did not include padding of the tuning capacitors. I have a set of generators with two or even three paralleled capacitors, illustrating what happens over the years with multiple tunings.

              Comment


              • #13
                Thanks, I had a suspicion they were high quality ,as that is what Allen usually does! First I 'll try padding with the decade box as it is the least destructive experiment. Then I 'll delve further.
                Can't play an note but love all things "organ" Responsible for 2/10 Wurli pipe organ, Allen 3160(wife's), Allen LL324, Allen GW319EX, ADC4600, many others. E-organ shop to fund free organ lessons for kids.

                Comment

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