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Wulitzer 4570 Entire Tibia Octaves Dead or Weak

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    Wulitzer 4570 Entire Tibia Octaves Dead or Weak

    Wurlitzer model 4570.
    Could also apply to models 4573, 4370, 4373.

    An entire octave of some Tibia stop footages is dead or very weak as shown in the attached picture. The blue-shaded keys are dead or very weak.

    This problem started suddenly.

    All other keys on the manuals work normally for each Tibia stop. All other stops work normally.

    Please let me know the likely defect, and where to begin troubleshooting.

    I have the schematic diagrams.

    #2
    From your diagram it looks like it might just be one octave that is dead or weak as the octave shifts with the 2', 4' and 8' pitches. I don't have this model, I have a Wurlitzer 950. I don't know about your schematics or if you have the service manual, but if the service manual for your model is anything like mine, it has documentation in the beginning of the service manual which is very helpful. If you are in the USA, you can try contacting Morelock Music in Rienzi, MS. They were very helpful for me and they have all the Wurlitzer organ parts.

    Comment


      #3
      Originally posted by you795a View Post
      If you are in the USA...
      Neither of you have completed your User Profile to show your location It is helpful to others.
      Last edited by RogerM; 07-26-2019, 01:22 AM.
      Previous: Elka Crescendo 303, Technics G7, Yamaha EL-90
      Current: Yamaha AR-100

      Comment


      • RogerM
        RogerM commented
        Editing a comment
        Both profiles now updated. Excellent stuff 😀

      #4
      Follow tibia signal IV from keying on page 21 to page 26. There you will find the tibia IV filter board. Check that the soldering to the mother board is good.
      td

      Comment


        #5
        Originally posted by tucsondave View Post
        Follow tibia signal IV from keying on page 21 to page 26. There you will find the tibia IV filter board. Check that the soldering to the mother board is good.
        td
        Hello tucsondave,
        Thank you for the instruction. I resoldered the Tibia III/IV filter board to the mother board. That corrected all of the problems except the lower manual, 8' Tibia, top octave is still dead. Is there another place to look?

        Comment


          #6
          If the LM 8' top octave is dead but the 4' an octave down is good then check the tab switch or the 12 k resistor. If both are still bad then check wiring. (Page 21)
          td

          Comment


            #7
            Originally posted by tucsondave View Post
            If the LM 8' top octave is dead but the 4' an octave down is good then check the tab switch or the 12 k resistor. If both are still bad then check wiring. (Page 21)
            td
            The remaining trouble with the lower manual, 8' Tibia, top octave being dead was simply that one of the flexible contact wires on the 8' stop switch was out of its slot.

            I buttoned up the cabinet, tested it out, but now all of the upper manual red voices (8' Melodia, Horn Diapason, String, Trumpet, Kinura) on the next to highest octave C# to C inclusive are dead. Same on lower manual when 8' Upper to Lower coupler is on for those voices.

            Grrr.
            Last edited by Bucky; 07-29-2019, 12:42 PM.

            Comment


              #8
              Additional problem with Wurlitzer model 4570.
              Could also apply to models 4573, 4370, 4373.

              ■ Two entire upper manual octaves of one or any combination of 8’ Red stops (Melodia, Horn Diapason, String, Trumpet, Kinura) are dead as shown in the attached picture. The blue-shaded keys are dead.

              ■ When the 8' Upper to Lower Red stop coupler is on, the lower manual exhibits the same dead keys, also as shown in blue.

              This problem started suddenly.

              All other keys on the manuals work normally for each Red stop.
              All other stops work normally.

              Please let me know the likely defect, and where to begin troubleshooting.

              I have the schematic diagrams.

              Attached Files
              Last edited by Bucky; 08-10-2019, 01:50 PM.

              Comment


                #9
                Look at the lower left of page 18. The white and Lt Green wires carry the signal from C# (38) to C (61).
                Check continuity from the DC keyer (page 19) to the upper STRAF boards beginning on page 12.

                td

                Comment


                  #10
                  I have found the problem with the red voices. Three of the four shielded cables leading from the D.C. keying board to disconnect O (Percussion) at the treble end of the STRAF broke off the disconnect terminals due to raising and lowering the STRAF over the years.

                  There is one remaining problem: only the shielded cable from notes 26 thru 37 did not come loose. The other three, for notes 1 thru 25, 38 thru 49, and 50 thru 61, need to go to disconnect terminals 2, 4, and 5, but which goes where? There does not seem to be an identification in the schematics.

                  A copy of a portion of schematic Page 12 is attached. The input circuitry is slightly different for each series of notes going to the MELODIA filter.

                  I also made a diagram, attached, of the rear of disconnect O showing which terminals have intact connections and the three that are broken off.
                  Click image for larger version

Name:	4570 Page 12  FILTERS UPPER STRAF #2 D.C. SCHEMATIC.JPG
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Size:	81.4 KB
ID:	662794Click image for larger version

Name:	4570 DISCONNECT LETTER O PERCUSSION a.jpg
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Size:	71.7 KB
ID:	662795
                  Once I know which is which, I will need to reattach the wires. Is there a procedure for removing terminals from the disconnects?
                  ...or, is there a source for the same type of disconnect?

                  Comment


                    #11
                    Are the colored markers missing from the cables? Pg 12 shows the color on the cable and the numbers in the square with the "O" indicate the pin.

                    There was a tool for removing the pins. You may be able to solder the wires to the pins using a fine pointed soldering iron tip.
                    td

                    Comment


                      #12
                      Originally posted by tucsondave View Post
                      Are the colored markers missing from the cables? Pg 12 shows the color on the cable and the numbers in the square with the "O" indicate the pin.
                      td
                      The color codes on the schematic page 12 mentioned above (PINK, LT. BLUE, LT. GREEN, WHITE) are for the wires that exit disconnect O on the STRAF side of it and lead to the MIXER B and MELODIA boards. The shielded cables that come to this disconnect from the D.C. KEYING BOARD are not marked. Attached is a copy of schematic page 19 showing where the four shielded cables are attached to the D.C. KEYING BOARD, and the note numbers that are related to each of the four cables.

                      The connections to the rear of Disconnect O are shown in the second photo attached. The white and black wires and shielded cable to terminal 3 leading from D.C. KEYING BOARD (notes 26 through 37) had not come loose. The other three shielded cables had broken off the disconnect.
                      Without a diagram that shows which cable goes where, I determined which is which by listening to the evenness of brilliance and timbre of the MELODIA stop as the three loose shielded cables were moved among disconnect terminals 2, 4, & 5. The reason it matters is that the input resistors and capacitors to the MELODIA board are different for the four key ranges, thus affecting the sound of each section.

                      Click image for larger version  Name:	4570  Page 19  P.C. BOARD D.C. KEYING - 56 NOTES.JPG.JPG Views:	0 Size:	83.5 KB ID:	662844Click image for larger version  Name:	4570 DISCONNECT LETTER O PERCUSSION correct connections.jpg Views:	0 Size:	87.6 KB ID:	662845

                      I believe I will replace one or both sides of disconnect O because I cannot seem to get the terminals that the wires broke off of out of it. I think the following kit may replace the original: Molex 76650-0067.

                      tucsondave, thank you very much for the advice and guidance on how to fix the dead Tibia notes and now the dead Red stop notes.

                      --------------------------------------------------------------


                      FYI, I have owned this organ and Leslie 212S since new in 1973. A year ago I replaced all of the electrolytic capacitors in the organ amplifiers and in the power supplies, along with any 5 mF or larger capacitors elsewhere and a few 1.5 mF or larger. I also recapped the Leslie console connector.

                      Gotta keep these antiques going! I hope to get many more years of life out of this set. It plays like new now.

                      Comment


                        #13
                        Try contacting Morelock Organ Parts and Service in Riezni, MI. They were very helpful for me with my Wurlitzer 950 organ.

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