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Needing Advice - A100 Vibrato weak sounding, almost non-existent?

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  • Needing Advice - A100 Vibrato weak sounding, almost non-existent?

    Hi All! You all here in this gracious forum helped me get my Hammond M come alive again some years ago, and this time I'm back having just acquired a beautiful A100 -- I'm BEYOND excited!!! Anyhow the organ is in great shape, but the only issue I've found so far is the Vibrato really isn't noticeable on any of it's settings. I DO notice a bit of brightness that kicks in when I turn the Vibrato on, but besides that, there is very little to no extra vibrato that gets added to the sound when engaged.

    I might quickly add that I am a true and through NOVICE when it comes to electronics. But I did at least try "zapping" the vibrato scanner with two 9v batteries. This didn't seem to make any difference.

    So now I'm wondering if I'm going to actually go ahead and pull the scanner out and do a full clean out? If I must, I will, but I have to admit this sort of mission is QUITE intimidating for me! So before I go for it, I just want to check in with any of you Hammond Genius' here in the forum to see if you might recommend other courses of action to take before pulling out the scanner?

    All ears and thanks in advance for the wisdom!

  • #2
    Sounds like the scanner is stuck, and not turning. It's possible to remove the end cap of the scanner and see if it is turning. It's also possible to nudge it with a well placed finger to get the rotor to turn again. You must be careful not to bend the needle like contact in the center of the rotor. I have successfully re-started most scanners without removing them with this method. Of course, if you have the time etc. removing and cleaning the scanner is the better, longer lasting option.
    Good luck!

    Geo

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    • #3
      Indeed, this sounds exactly like the symptoms my M-111 had when I first got it. Turning on the vibrato would result in a change of tone (due to the delay line and a different pre-amp input), but no actual vibrato. My scanner was really badly stuck; even getting it apart was hard.
      Stefan Vorkoetter: http://www.stefanv.com

      1962 Hammond M-111 with Improved Vibrato, Internal Rotary Speaker, Drum Machine,
      Window Seat Tone Cabinets, Completely Rebuilt Amplifier, and Recapped Tone Generator.
      1978 PAiA 1550 Stringz'n'Thingz with many enhancements.
      2017 Raspberry Pi organ-top synthesizer.

      Comment


      • #4
        Hello,

        I give you my advice, but before a few words about the delay line which is after the scanner another critical component of the vibrato.

        It is composed of several delay cells that are selected in turn by the scanner to produce the vibrato effect.
        All these cells consist of a self and a capacitor.
        The last cell is a terminating resistor that absorbs reflections.
        The operation is very sensitive to the quality of the capacitor and to the value of the terminating resistor.

        I come to the point :

        If your delay line is equipped with paper oil capacitors. Their value increases a lot over time and instead of delaying the signal they absorb it. You must have to replace them all.
        I remember micamold capacitors whose value had increased by 36x.
        Look also at the capacitors that are above the generators. Often it's the same brand.

        https://picclick.com/Vintage-Micamol...523840524.html

        JP

        Comment


        • #5
          Old capacitors will muddy the sound, but they won't make the vibrato imperceptible. The OP's symptoms really sound like the vibrato isn't working at all.

          http://www.stefanv.com/electronics/h...brato_mod.html
          Stefan Vorkoetter: http://www.stefanv.com

          1962 Hammond M-111 with Improved Vibrato, Internal Rotary Speaker, Drum Machine,
          Window Seat Tone Cabinets, Completely Rebuilt Amplifier, and Recapped Tone Generator.
          1978 PAiA 1550 Stringz'n'Thingz with many enhancements.
          2017 Raspberry Pi organ-top synthesizer.

          Comment


          • #6
            Originally posted by geoelectro View Post
            Sounds like the scanner is stuck, and not turning. It's possible to remove the end cap of the scanner and see if it is turning. It's also possible to nudge it with a well placed finger to get the rotor to turn again. You must be careful not to bend the needle like contact in the center of the rotor. I have successfully re-started most scanners without removing them with this method. Of course, if you have the time etc. removing and cleaning the scanner is the better, longer lasting option.
            Good luck!

            Geo
            Ok wow thank you friends! So my intuition is THIS is exactly the problem -- the scanner itself is stuck and not turning! I just watched a youtube vid of someone taking apart the entire scanner (ugh I'm really hoping I can avoid this!) but it helped me wrap my head around what the end cap section is. So I just want to check you guys before I start fiddling -- is it possible to remove this end cap WITHOUT taking the actual entire scanner out of the organ??

            From pics online I can see there are 2 screws on the cap I'll need to remove before I can get my finger in there and carefully try to move the scanner. Just wondering if I need to do anything else first before attempting to remove the end cap? Do I need to mess with scanner motor at all or I can leave be? Any additional tips you guys might have for this procedure please don't hesitate to let me know!

            Thanks again!!

            Comment


            • #7
              I open the end cap without removing anything. Takes a stubby screwdriver for the back screw and an agile hand.

              Geo

              Comment


              • #8
                UPDATE -- Ok so I was able to get the end cap off without removing the whole scanner, and what I found is that it was spinning -- but SLOWLY. I ended up nudging it with the organ off again, and I swear now it is spinning even SLOWER than before I touched it. I hope I didn't mess it up more somehow... but indeed, at this point it is just BARELY turning. Anything else anyone here would recommend before taking out the whole scanner? What is making it turn so slow you think? Thank you so much for taking the time to answer!!

                Comment


                • #9
                  Oil? I think the scanner is driven through a slip clutch arrangement, so if the scanner bearings aren't lubricated well it could turn slow or stop. Mine on my E100 was fine at first, then started squealing. I had to wait a few days for the oil to reach the bearings then all was well!
                  Tom in Tulsa

                  Fooling with: 1969 E100, 1955 M3, 1963 M100, Leslie 720

                  Comment


                  • #10
                    Originally posted by A.White View Post
                    UPDATE -- Ok so I was able to get the end cap off without removing the whole scanner, and what I found is that it was spinning -- but SLOWLY. I ended up nudging it with the organ off again, and I swear now it is spinning even SLOWER than before I touched it. I hope I didn't mess it up more somehow... but indeed, at this point it is just BARELY turning. Anything else anyone here would recommend before taking out the whole scanner? What is making it turn so slow you think? Thank you so much for taking the time to answer!!
                    My "trick" is to nudge it while it's running. As it turns slowly I nudge it to go faster. It makes a lot of noise when you touch the rotor so adjust the organ volume accordingly. You can tell as it frees up it will have less resistance. Of course the oiling tub on the motor should be freshly oiled. I also drop oil directly on the strings going into the scanner to speed up the process.

                    Geo

                    Comment


                    • #11
                      Feel dumb asking -- but what Geo what do you use to nudge the rotor? There isn't much space to work with since the end cap is still connecting via the wires, but yesterday I was using a screwdriver with the organ turned off... Would it be save to use a screwdriver even with it turned on, or should I try and find something less conductive? Thanks for these tips!!

                      Comment


                      • #12
                        Originally posted by A.White View Post
                        Feel dumb asking -- but what Geo what do you use to nudge the rotor? There isn't much space to work with since the end cap is still connecting via the wires, but yesterday I was using a screwdriver with the organ turned off... Would it be save to use a screwdriver even with it turned on, or should I try and find something less conductive? Thanks for these tips!!
                        Yes, it’s safe, however I use a well placed finger.

                        Geo

                        Comment


                        • #13
                          I like to:
                          * loosen the 4 nuts that hold the motor to its bracket, pull the motor-scanner assembly to the left and twist it 90 degrees so the back of the scanner is facing me.
                          * Remove the end cap as well as the 2 screws holding the phenolic mount for the brush contacts, and then take the brushes off and put the cap/brush assembly to the side

                          Now there's plenty of room and plenty of access. You won't have the help of the sync motor turning while getting the scanner loose this way, but on the other hand you won't be putting wear on the slip drive either.
                          Current organs: AV, BC, A-100
                          Current Leslies: 22H, 142, 147, 760
                          Organs in the past: L-100 (several), M-100 (x2), T-100, E-100, CV
                          Other keyboards: Roland FP-4, Yamaha DX7, Yamaha TX81Z, Yamaha Motif ES Rack, Korg Krome, Novation Mininova

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