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Hammond T-200 - Help Wanted!

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    Hammond T-200 - Help Wanted!


    #2

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      #3
      G'day Ricko!
      I'll be with ya soon.

      Er... later.
      It's Monday morning here, and work's off to a bad start.
      I'll B back...

      -Brendooon
      -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.

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        #4

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          #5
          >Did you ever get that percussion issue on your T fixed?

          Agh, no.
          I can't muster the brain power to conquer that one... Uber, extended mega concentration required.

          That pedal rumble's interesting on your rig....
          -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.

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            #6
            https://www.dropbox.com/s/ex3eigz0tg...umble.MOV?dl=0

            Hard to hear it through phone speakers because of the frequencies, but sounds like thunder.

            As you can hear in the vid, with bass drawbar in the organ is pretty quiet and manual keys are all good!

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              #7
              Dang, it sounds identical to the wind from a close mic'd leslie!

              As I was drifting off to sleep I remembered something about 'dem ol' pedals that might be worth checking.

              If I remember rightly, the boards on the pedals are mainly just the triggering system. I think that includes the part which makes sure only one pedal sounds at a time.
              That's essential for the poor ol' analogue octave divider which can only do one note at a time.

              Now, that dividing is done on the pedal preamp... set between the power supply board and the main amp, middle o' the chassis.
              It'll shove anything it gets down an octave or two
              (urgh! The forum's misbehaving and I have to type slowly. Every second letter gets missed otherwise)
              SO it may even produce that noise with the pedals unplugged.

              I reckon if you study the pins on the divider board you may discover something.
              I'll go look up my notes from my last pedal problem and see if there's anything of interest.
              -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.

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                #8

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                  #9
                  Does the rumble still appear if the input from the pedals is detached?
                  -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.

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                    #10

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                      #11

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                        #12
                        C750 is the timing capacitor to produce the pedal erase pulse at the collector of Q751. Check for that pulse. Check for the 13 v with a pedal pressed. Also check for the 12 v at the emitter of Q752 when keyed.
                        Disconnect pin 9 on pedal board #3 to see if the rumble changes at all.
                        Make sure all grounds are good.
                        Your description indicates that all pedal keyers are leaking audio to the divider board.

                        td

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                          #13

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                            #14
                            Ok - so had a chance to the checks tests by TD.

                            Q751 collector - 1.2mv to 1.7v when keyed. No where near 13v as suggested.

                            Q752 emitter. Sitting at 15.87v unkeyed. Drops to 15.71when keyed (ie marginal drop).

                            Rumble disappears with pin 9 disconnected at keying board 3. Tones no longer played when key. But can hear clicking when each pedal is keyed.

                            Checked grounds on keying boards using continuity function and seem ok.

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                              #15

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