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  • B3/122 Motor Speed Switching Issue

    Hi all,

    First, I cannot tell you how helpful this forum has been to me over the years. 14 years ago I bought my '58 B3 from a church in Illinois for a $25 donation (they wouldn't accept more...they needed their basement storage space I guess). It lived with me in college, its been with me living in 4 different states literally from coast-to-coast. I found a Leslie 122 cabinet at another church that had been scrapped for parts and was able to make a trade for it. So for the last 14 years I've been working on the B and the Leslie as I've had time and money to do so. Two years ago, I finally had a really great Hammond tech come and install the half-moon kit so I could use it with the 122 and it was a dream come true.

    Now, after a cross-country move and then another move over the Rocky Mountains, something isn't right. Everything sounds really great, but the motors don't switch speeds any more with the half-moon switch. Thanks to many of you on this forum, I've done a lot of troubleshooting, but I think I'm at a dead end for my current knowledge level and would love any help you're willing to give.

    -------------------------------------
    SYMPTOMS:
    B3 fires up like normal, but when Leslie kicks on, it doesn’t go through the “warm up” sequence with motors changing speeds. B3/Leslie sound amazing as ever, everything seems to be ship shape. When I throw the half-moon switch, there is no click from the relay, and the motors stay stuck in one speed.

    TROUBLESHOOTING I'VE DONE TO DATE:
    Confirmed that all motors work when individually plugged in to wall

    I took preamp out of the Leslie (but left it plugged in) and manually engaged the relay on the underside...motors switch normally when I manually push the relay

    I switched the two 12au7 tubes on the preamp, and no change...still sounded great, but no motor switching

    I visually inspected the half moon switch connections and the “kit” inside the B...everything looks great (the tech who worked on it is really incredible)

    I replaced the rectifier tube in the Hammond preamp and no change...still sounds great, but no motor switching

    Visually inspected both ends of the Leslie cable and everything seems good

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

    So. In your expert opinion, where should I go next? If it's time to start checking voltages on things, could you please also recommend a great meter for this type of work? And FYI, my electrical experience is novice. I'm comfortable enough to install a ceiling fan or switch out a light fixture...and I know my way around the Leslie pretty well...but I know stuff gets intense and I definitely don't want to fry the organ (or MYSELF)! If it's time for a tech, can you recommend anyone that may be able to help in Colorado? My searching has turned up no one.

    Thanks in advance for your time reading this long post, and for any help you might give! Keep screamin', everybody!

    Cheers,
    DH

  • #2
    George Benton has some really good information on his site: https://bentonelectronics.com/servic...2-amplifier/#7

    You will need a meter to measure the switching voltage. Any digital meter should be ok as long as you have some decent leads. Does you organ have the 6x4 adapter to provide power to the kit?

    Jim

    Comment


    • #3
      In a stock setup, the default speed would be fast. Any failure of the switching tube, or loss of switching voltage would have the Leslie running fast. So the first thing I look at is ...are the motor wires in the correct socket? Brown to the left, white to the right. Sometimes these get reversed. If that was the case, then being stuck on slow would actually mean stuck on fast. Stuck on fast which is more common would lead me to check if the switching voltage is present AND if the amplifier DC voltages are within range. Either can cause no switching.

      Geo

      Comment


      • #4
        Jim, thank you! I have been referencing that section of the Benton site a lot lately! Is the 6x4 adapter that you're talking about the black cylindrical "plug" that goes in the Hammond preamp with the rectifier tube then plugging into that black cylinder? If so, yes I do have that and the wires coming out of it seem fine, and are connected well inside the kit.

        Geo, I'm star struck that you responded here...your many posts on other threads have been so helpful! Thank you! I can confirm that the motor plugs are in the correct sockets, and we are stuck in fast. Could you let me know how to go about checking switching voltage and amplifier DC voltages? Meter recommendation, and procedure? I can't thank you enough!

        Cheers!
        DH

        Comment


        • #5
          I had this same problem with my C3/122. After consulting with techs and checking voltages it turned out to be a simple adjustment on the Leslie. Check the four long screws hanging down from the top rotor motor. Try backing off these screws slightly. It could be only one of the crews so try one at a time to see if it makes any difference. If one or more are too tight the Leslie doesn't go through the warm up phase and won't switch to fast speed from the console switch.
          Hammond C-3/Leslie 122, Hammond M-102A, Vox Super Continental, Farfisa Combo Compact

          Comment


          • Sweet Pete
            Sweet Pete commented
            Editing a comment
            I suggest a thorough read of the 1970 version of 122/147 service manuals.Pictures worth a thousand words.
            Earlier version of manual less informative as the dual stacks developed 'issues' by '70.

          • DavisH
            DavisH commented
            Editing a comment
            Thanks, LMF! I will try this first, hopefully tomorrow. Hope this is the solution! :)

        • #6
          After confirming pin 5 on your cable is 100% working,confirm the B+ voltage before and after the 33K resistor on the 6X4 tube adapter is correct.
          Yep.the Benton site is very helpful,thanks again geo!

          In the middle of the motor stacks the adjustment nut on the height shaft of an o-ring/pulley is all explained in the 1970's service manuals.
          Which I read in 1971 when I was young with no internet.
          Still somehow managed.......I have rebuilt at least a hundred 'stacks'.
          Still working on the mall organ coffee table book for cork sniffers

          Comment


          • #7
            Unless I missed it, I have not seen the 428/8000 relay box mentioned here.
            I rebuild Hammonds and Leslies. Please visit my website. tbstonewheels.com It's still in the works but is up and running. My personal setup is a Model A # 2203 with Trek II percussion, 122RV and 2 31h's. One is fitted with two speed motors and the other a Hamptone. Also sporting a working Vibratone 30A # 326.

            Comment


            • #8
              Is the 6x4 adapter that you're talking about the black cylindrical "plug" that goes in the Hammond preamp with the rectifier tube then plugging into that black cylinder? If so, yes I do have that and the wires coming out of it seem fine, and are connected well inside the kit.
              In that case, the organ is providing the switching reference voltage. Unplug the Leslie cable at the Leslie and with a meter set on DC, you should see the voltage vary from approx 80 ish volts DC to O VDC metering between pin 2 Gnd and pin 1 SIgnal. when you flip the tremolo switch. If the voltage is good, then the problem is in the Leslie, No voltage, then the problem is in the 6X4 adapter or kit.

              Jim

              Comment


              • DavisH
                DavisH commented
                Editing a comment
                Thank you, Jim! I'm going to try loosening the four top rotor screws and see if maybe their tightness is the issue first, and then I'll check the things you've suggested here. Do you have a specific meter that you recommend for this, or do I just need to browse around the local hardware store? Thanks again for all of your time and help!

            • #9
              Originally posted by Sweet Pete View Post
              After confirming pin 5 on your cable is 100% working,confirm the B+ voltage before and after the 33K resistor on the 6X4 tube adapter is correct.
              Yep.the Benton site is very helpful,thanks again geo!

              In the middle of the motor stacks the adjustment nut on the height shaft of an o-ring/pulley is all explained in the 1970's service manuals.
              Which I read in 1971 when I was young with no internet.
              Still somehow managed.......I have rebuilt at least a hundred 'stacks'.
              Hey Pete! Do you know of anywhere online that the 1970's service manuals exist?

              Comment


              • Sweet Pete
                Sweet Pete commented
                Editing a comment
                A few years before finding The Organ Forum I located Captain Foldback.The selection of Leslie manuals and technical bulletins there is helpful.
                Might have a '70 or newer 'dual stack' model with exploded diagram in there of everything as it should be.Site owner is Hamtech admin......
                Then I needed hookup kits for Leslies and I discovered the Fish Organs list of schemos/diagrams and model numbers.
                Since then I have built over twenty Leslie interfaces.

            • #10
              You have already confirmed that the motors work individually. Unplug the slow motors and confirm they are disengaged. Power up the rig and see if you have fast/stop operation. If it stays on fast, you have an electrical switching problem.
              I know Home Depot carries meters. What sources do you have available.

              Jim

              Comment


              • DavisH
                DavisH commented
                Editing a comment
                Hi Jim!

                I unplugged the slow motors, powered up the rig and both rotors remained in fast regardless of throwing the half-moon switch. Seems like an electrical problem! I'm headed to Home Depot today to pick up a meter and will have a look at pins 1 & 2! Can't thank you enough for your help and expertise!

              • DavisH
                DavisH commented
                Editing a comment
                Hi Jim!

                Got a multimeter and just tested the Leslie cable at the Leslie end as suggested. The volts I was reading was between 4-7V with no change at all when flipping the switch. My guess is this voltage is too low? :) This suggests a problem with the 6x4 adapter or the kit, is that correct? Next steps?

                Can not thank you enough for helping me work through this!

            • #11
              Hi all! A quick update:

              Got a multimeter and just tested the Leslie cable at the Leslie end as suggested. The volts I was reading was between 4-7V with no change at all when flipping the switch. My guess is this voltage is too low? :) This suggests a problem with the 6x4 adapter or the kit, is that correct? Next steps?

              I did also test the resistance in each socket of Leslie cable and it seems the cable is just fine!

              Thanks so much to all for your help!

              Comment


              • #12
                There is a 33k resistor inside the 6X4 interceptor (the plastic fitting that goes between the tube and amp chassis). These are known to drift upward or open up over time. You can measure that from where the wire from the interceptor come into the kit and the interceptor pins. (Keep checking pins till you get a reading.)


                Unfortunately, I've never been able to open up one of those interceptors without having it crack, so if that 33k resistor is bad, you usually have to find a workaround like mounting a 33k resistor under the preamp chassis.
                I'm David. 'Dave' is someone else's name.

                Comment


                • DavisH
                  DavisH commented
                  Editing a comment
                  Thank you, David! Apologies for the dumb question (I'm a total rookie here). What readings should I be looking for to know if resistor is good or bad? And do I just unplug the interceptor from the preamp chassis, turn the B3 on, then use the multimeter on each pin to get the readings?

              • #13
                The adapter has a resistor inside which goes to the wire tap and one of the pins. To measure, connect one lead of your meter to the wire, then touch each pin one at a time looking for any reading other than infinity. Typically, resistor measurements are best out of circuit. So yes, adapter unplugged. As for the reading you want, the 33K ohms resistor would read 33K ohms if good with a + or - 10% tolerance.

                The way I look for switching B+ is to set the speed switch to slow, then connect one lead of my meter to the Leslie amp chassis, then slightly pull the 6-pin Leslie cable off enough to expose the plug pins so I can get my meter lead in to touch either of the top two pins. I need to see at least 35~40Vdc and could be as much as 100Vdc.

                Geo

                Comment


                • #14
                  Thanks, David and Geo!

                  Finally had time to take some readings on the adapter/resistor. First, my MANY sincere apologies for so many rookie questions, and if I've made a mistake in the process. Since I've literally never done anything like this before, and it's my first multimeter, etc...let me describe the process so y'all can make sure I actually took the readings correctly (if you don't mind). I unplugged the 6x4 tube from the adapter, and removed the wire nut on the connection between the brown wire coming out of the adapter, and the brown wire leading into the kit.

                  Click image for larger version

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                  I turned the B3 on.

                  I then touched one lead to the exposed wire and the other I moved from socket to socket in the adapter.

                  I don't know if these are correct socket identification numbers, but I started with the socket to the left of the "gap" (I'll call it #1 for now), and then worked my way around. These are the readings:

                  Socket 1 (left of the gap): 32.1k
                  Socket 2: 0 (but I could hear a faint crackle in the Leslie speakers when touching lead to this socket)
                  Socket 3: 0
                  Socket 4: 28.1k
                  Socket 5: 27.8k
                  Socket 6: 0
                  Socket 7 (right of the gap): 0

                  And here was the meter setting I was using (just in case I was looking at the wrong thing). Thank you all so much for your time and help!!!

                  Click image for larger version

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                  Attached Files

                  Comment


                  • #15
                    Clarification...when measuring resistance you want to ideally do it "out of circuit". So the same thing, except unplug the adapter completely from the organ. It appears you may have found the 33K resistor but try it out of circuit. The pins are numbered looking from the bottom, clockwise from the gap.

                    Geo

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