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  • Hammond T400 - Leslie Switch and HK Tube

    Hey folks,

    I just finished generator service of a completely stuck T400, and drawbar/switch cleaning respectively. Now everything seems to work again (set aside one single tone in every octave, I suspect a generator problem with tone #50, and the vibrato that does not vibrate at all... but that is a different story).

    However, I wonder whether there is a possibility to attach a foot switch for the built in „leslie“ unit. It is very inconvenient to have only the hand switches left of the lower manual for that.

    And secondly, I think about the possibilty to integrate a Hughes & Kettner Rotosphere Tube in the signal chain, thus hitting two scores at once (Leslie and Tube overdrive). What do you think? would that be an interesting approach, and which layout scheme should I consult to decide where to connect it?

    Idea: bridge from preamp in with an A/B-switch to the HK, and from the HK out back into the organ main amp - cause the speakers are really good IMHO.

    Thanks for your opinion on this

    greetings, Jesaiah

  • #2
    Hi Jesiaiah,
    I'm just ducking in briefly now but I'll be back later re overdrive etc.
    I had a T500 which had a momentary footswitch on the side of the swell pedal. Does the T400 have that? It's for turning the rhythm machine on, but it can be rewired for leslie.
    Tonewheelgeneral.com also sell sideswitches.

    You can use the switch for turning the leslie to fast, it stays fast while you've got it pressed and then ramps back down to off/slow depending on what you've got it switched to. The ramp down is slower if you've got it switched to off, so you can nicely replicate slow by just touching the switch every now and then. It was very expressive, loved it!
    If you run wires from the fast side of the switch to the pedal it should do it. You're just running 12V to the relay.

    Ah, I just remembered the internal leslie is always spinning. You can install a plain old light switch under the lower manual in line to the power wire to the slow motor. more on that later.
    -1958 Hofner 550 archtop guitar -1959 C3 and PR40- -1964 Busillachio Harmonium- -1964 M101-
    -1967ish Leslie 122- -1975 T500 (modded..chopped, and reassembled!)-
    -DIY 760 FrankenLeslie/rat hideout-
    -1980 Electrokey Electric Piano- -Yamaha electric Harmonium (early 80's?)-
    -1990 Jansen GMF150 amp- -1992 Korg 01W/fd- -1992 G&L S-500 geetar.

    Comment


    • #3
      Don't waste time with a Rotosphere.
      Get a Mini Vent II.
      Current:
      1971 T-202 with Carsten Meyer mods: Remove key click filters, single-trigger percussion, UM 16' drawbar volume correction. Lower Manual bass foldback.
      Korg CX3 (original 1980's analogue model).
      1967 Leslie 122 with custom inbuilt preamp on back panel for 1/4" line-level inputs, bass & treble controls. Horn diffusers intact.
      2009 Marshall 2061x HW Plexi head into Marshall 4x12 cabinet.

      Former:
      1964 C3
      196x M-102
      197x X5
      197x Leslie 825

      Comment


      • #4
        @Papus: The vent is sort of overkill imho - I am planning to wire back in the organ speakers thus remaining in the realm of mono signals.
        And the vent is somewhere in the $300 region whereas the rotosphere can be found for 100 (used but in good condition) ...

        Comment


        • #5
          @Brendon: I will check for that switch, thanks a lot !
          Is there a wiring chart for the T400 leslie available?

          And btw, if you have any ideas concerning the (missing) vibrato, I would be grateful too...

          greetings, j

          Comment


          • #6
            there's not much on the leslie itself, the details are hidden off to one side in the overall organ diagram, if you can work it out.

            First place to look for the vibrato is to see if the organ's motor still has a rubber belt attached between it and the vib scanner.
            -1958 Hofner 550 archtop guitar -1959 C3 and PR40- -1964 Busillachio Harmonium- -1964 M101-
            -1967ish Leslie 122- -1975 T500 (modded..chopped, and reassembled!)-
            -DIY 760 FrankenLeslie/rat hideout-
            -1980 Electrokey Electric Piano- -Yamaha electric Harmonium (early 80's?)-
            -1990 Jansen GMF150 amp- -1992 Korg 01W/fd- -1992 G&L S-500 geetar.

            Comment


            • #7
              In this model, the vibrato scanner (or what I think it is) is mounted at the right side of the generator opposite to the motor. I have not seen a belt yet (it is mounted REAL tightly), but it seems to me that the transmission shaft that goes into the brass box seems to rotate smoothly.

              Comment


              • #8
                Dang, I'd posted daft information into my memory!
                For some reason I'd started to imagine the T300 and T400 would have the same scanner as the T500, rather than the decent one you've got.

                So that means the Scanner is AOK.

                Okay, next step is to use a marker pen to show the position of the trim-knob on the vibrato preamp (the board with the transformer on it).
                Twiddle that and see if it brings vibrato volume up.
                Be sure to put it back in the right position if it DOESN'T affect the Vib, because it also affects the clean volume. It's more like a balance control rather than a straight volume.

                After that check behind the tabs to see if any cables appear to have broken off. Have a good look, because sometimes the wire is hard to spot, having slipped away from the area it belongs in.

                While you're at it take good clear photos of everything as reference for a later time. Wires will break occasionally and these photos are hugely valuable for finding where they ought to go.
                -1958 Hofner 550 archtop guitar -1959 C3 and PR40- -1964 Busillachio Harmonium- -1964 M101-
                -1967ish Leslie 122- -1975 T500 (modded..chopped, and reassembled!)-
                -DIY 760 FrankenLeslie/rat hideout-
                -1980 Electrokey Electric Piano- -Yamaha electric Harmonium (early 80's?)-
                -1990 Jansen GMF150 amp- -1992 Korg 01W/fd- -1992 G&L S-500 geetar.

                Comment


                • #9
                  Thanks a lot for the feedback! I will give it a try this weekend and keep you up-to-date if you dont mind ...

                  Comment


                  • #10
                    I just noticed I did not update the progress on this ...
                    Thanks again to Brendon Wright and all the others that provided me with valuable information. I managed to slide out the vib gen side of the generator block far enough to get inside the unit. A dose of medical benzine, soaking with a mixture of hammond oil and benzine 1:1 and finally reoiling with original oil did it (along with some mechanical motivation using a small screwdriver and in a very, very careful manner).
                    The T400 is almosrt completely up and running again (one generator coil seems to be dead, but I can live with that).
                    Now I am turning on the instrument every week for 30 minutes minimum - if I have time, more often for fun :)

                    Comment


                    • Papus
                      Papus commented
                      Editing a comment
                      install a new motor run cap if you haven't already done so.
                      The old caps are time bombs, liable to explode - sending carcinogenic PCB oil and burnt paper everywhere.
                      New cap should be less than $20 and requires about 15 minutes to install

                  • #11
                    That's so good the hear, Jesiah!
                    I've got quite a number of T threads up in the browser I'm meaning to answer... it's harder to fit in than it once was!
                    -1958 Hofner 550 archtop guitar -1959 C3 and PR40- -1964 Busillachio Harmonium- -1964 M101-
                    -1967ish Leslie 122- -1975 T500 (modded..chopped, and reassembled!)-
                    -DIY 760 FrankenLeslie/rat hideout-
                    -1980 Electrokey Electric Piano- -Yamaha electric Harmonium (early 80's?)-
                    -1990 Jansen GMF150 amp- -1992 Korg 01W/fd- -1992 G&L S-500 geetar.

                    Comment

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