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All Bass Pedals play same (one) note...

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  • All Bass Pedals play same (one) note...

    Hi Everyone,

    Got a T222 in my workshop, and it has got a strange problem. When bass pedals are pressed down, the same note sounds regardless of wich pedal I press.
    Anyone knows whats going on?

    Best Regards,
    Jan

  • #2
    Probably a stuck contact in the pedalboard.
    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

    Comment


    • Jan Sjoberg
      Jan Sjoberg commented
      Editing a comment
      Even though it only sounds when any pedal is pressed, and not sound continously?

  • #3
    It seems to me the pedals on the T are like those on the M. They are monophonic so the contact is not like a light switch-on or off. As I may possibly mistakingly recall, there is another contact that enters into the equation for pedal sustain. That second contact or circuit should reset when some other pedal is played. It appears that is the stuck contact, not the one that makes it play, I would recommend downloading the service manual unless our friend Brendan the T expert chimes in.
    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.

    Comment


    • Jan Sjoberg
      Jan Sjoberg commented
      Editing a comment
      I've takin it all apart and measured each contact. There is a 1-pole two way switch at each pedal. All seem fine.
      It is the B note that sounds, regardless of wich pedal's pressed. Im leanin towards a transistor failure at the B note.
      Does any body know what these transistors are? Modern replacement?

  • #4
    I am getting really deperate here... Anyone?

    Comment


    • #5
      Each pedal has both a normally closed and normally open contact. Have you checked (with an ohmmeter) that every pedal opens and closes these contacts when pressed?

      Comment


      • #6
        Have you joined the Hammond Organ and Leslie speaker Technician's Network on Facebook?

        Comment


        • #7
          guylavoie: Yes. All contacts OK.

          DaveMcCarthy: No, didn't know there was such a group. I'll join immediately! Thanks!

          Comment


          • #8
            Is there someone who could explain the theory of the the pedal circuit? Or perhaps has a service manual for T-series?

            Comment


            • #9
              Google "Hammond T-500 service manuals" to find a good copy. It's similar enough to a T-200 to be totally useful.
              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

              Comment


              • #10
                Ok, thanks enor. I found the service manual. Measured 22v on the 15v line. Fixed that. Plus changed all power supply caps. But... Still the same problem! This is driving me crazy! Help! Anyone?

                Comment


                • #11
                  I'd try unsoldering the transistor for the stuck note on pedal switch board #3. If that stops it from playing the B note when any pedal is pressed, then you'd know that transistor is probably bad. I'd then try a general purpose NPN switching transistor (eg: 2N2222 or 2N3904) in it's place to see if that works.

                  Comment


                  • #12
                    I tried removing the cable to B note from generator. All other pedals plays a garbled noisy sound, no real note.
                    Desoldered transistor and diode on B note, measured with a transistor tester, both seems OK.

                    Could it be the divider board? Is there anybody who could explain the theory of how all this works?

                    Comment


                    • enor
                      enor commented
                      Editing a comment
                      Once again - read the service manual, the operation is thoroughly described there
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