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Hammond X-66 Reverb Amp issue

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  • Hammond X-66 Reverb Amp issue

    Dear community,

    the reverb tabs on my newly acquired X-66 do not work. I located the both reverb amps in the lower section of the organ, next to the spring reverb. All wiring seems to be OK, I did not measure any component on the PCB yet. I will do that once I have an X-66 service manual on hand, which I do not have right now.
    I wonder if the X66 has any other areas, that could impact the functionality of the reverb.

    The failure mode again:
    - no reverb at all, regardless of the tab position

    What I did:
    - located both reverb amps and the spring section, no loose cables, no "blown" electrolytic capacitors (as far as I could judge from the outside)
    - I 'shaked' the springs and did NOT hear any noise

    What I need:
    - a section from the service manual, that tells me what the inputs and outputs of the reverb PCB are
    - any hint, if there is any other location at the organ, that could affect the reverb functionality

    Btw - I found two bulbs inside of the organ ... are they somehow correlated to the reverb ? (just a thought as the M100 reverb section has two small bulbs in there)

    The attached picture shows both of the PCB's Click image for larger version

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    Cheers and thanks

  • #2

    Congratulations on your X-66.

    The light bulbs have to do with switching the presets. BTW do not rewire your presets unless the organ is unplugged. I believe they are live with 110 Voltage.USA. there should be a warning label back there to warn you of this! If you have the thing turned on with back open and push down two presets at once you will see the bulbs get brighter. has to do with switching....not a service tech...but I still should know the exact answer and I can't remember. Getting old.

    Because this is not a B3 type you probably won't want to customize your presets anyway. Most of them are really useful as is. and have etched labels anyway.

    Have you taken the back off the tone cabinet?. May want to unplug the RCA plugs on the amp to clean them. As I remember there are 5 of them. May have dirty contacts also work the tone cabinet cable to clean contacts for the channels. Just an idea, will cause scratchy audio and may be why reverb channel is missing. if the organ is on and you wiggle the tone cabinet cable you may get quite a lot of noise. keep the volume down or turn organ off when doing this.

    Very important that all the AC wiring in the organ be checked for dried out coatings. The organ is 50 or so years old and zip cord dries out. Change it all out to avoid a fire. You will see where the power comes in on the lower left and can trace the zip cord. I think one line runs up inside the left pedastal leg looking from the rear of organ. You can then track it across the inside of the organ. You should be able to thread a new piece of lamp cord down the tube from inside the organ.

    Here is a link to a US website for an organ club that uses the X-66. You will also find more interesting stuff about your instrument here...some of which you may already know. This links to the page about the aging wiring for the electric.


    This also might be a good time to fuse organ in case of any problems so you don't wipe out power supply??? Also, a grounded electric cord. Again if you are in UK or abroad I am not familiar with your plugs. I know we have to use a converter on international stuff in this country.
    Hammond used zip (lamp cord) for running the 110 voltage or whatever you operate on in the UK or overseas.
    Didn't help with your reverb question but... don't want to see you go up in flames before you get to play it.

    Ross R


    • #3
      I would suggest you look at the x-66 club website. Dan Vigin in Belgium has done extensive engineering, restoration and redesign work, and has several restoration articles listed there.
      Larry K

      Hammond BV+22H+DR-20, Celviano for piano practice
      Retired: Hammond L-102, M-3, S-6, H-112, B-2+21H+PR-40, B-3+21H, Hammond Aurora Custom, Colonnade.


      • #4
        Thanks Ross

        that was the first I have checked, thanks. The power cord is replaced already, the organ has a fuse.
        I do not plan to change the presets, as they are well selected. Thanks for the hint with the bulbs, I had no clue what they should do (I do not need light @ the inside of the organ)

        I will start now to work on the amp plugs, however I was not aware that there are any particular channels for reverb.
        By the way, do you own a pdf service manual ? Obviously this is difficult to get....


        - - - Updated - - -

        Thanks Larry
        I am already in contact with them and have asked to join the website. I have read Dan's presentations up and down, very helpful.


        • #5
          Service manual can be found here:



          • #6
            thanks !!

            Originally posted by matseke View Post
            Service manual can be found here:

            Thanks Mats, you made my day