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  • Power issues with BC/142, need help!

    I have a Hammond BC and Leslie 142 that recently started experiencing some power issues (I believe it is an issue in the Leslie amp). A few months ago, they started not always powering up...I could hear the TWG get up to speed while holding the start switch, but when I flipped the run switch it would die back down and never turn on. Sometimes it would turn on for a short time and then die within the first minute, other times (rarely) it would actually work and stay on. In these instances, I would know I was in the clear if it worked for more than a min or so, and could run for hours, but this started happening less & less and now doesnt work at all. If I hooked the BC up to a JR20 tone cab with the exact same cable, it would work fine. Also, if I hooked an instrument up to the Leslie w/ a UC-1A combo pedal (again using the same cable, just to eliminate that as the problem), the Leslie worked fine. So it would seem to be some sort of issue w/ the Leslie sending power back to the BC.

    Does anyone have suggestions in regards to further troubleshooting this issue and determining the culprit? I should also mention that I have the B+ power supply that came w/ the BC, which I never installed. I suppose worst case I could install that to power the organ & take a 1/4" out to the UC-1A, which would power the Leslie; I would rather figure out the real problem then complicating the signal chain w/ such an elaborate "solution" though.
    1940 Hammond BCV
    JR20 Tone Cab
    Leslie 142
    Trek II UC-1A
    CV w/ PR40 (in process of restoration)
    Crumar Mojo
    1972 Fender Rhodes Stage 73
    Wurlitzer model 206 "student electronic piano"
    Fender guitars: Custom Shop "1960" Strat (sonic blue w/ matching headstock), MIJ Tele w/ Bigsby (sunburst, double bound), MIM P-bass
    Gretsch guitars: Knotty Pines Round-up, Jet w/ TV jones & Bigsby (white w/ gold hardware)
    Martin 000X1AE acoustic
    Amps: Fender Princeton Reverb, Vox AC15, Traynor YCV40

  • #2
    Do you have a voltmeter? It's pretty easy to check whether or not the organ is getting B+ from the Leslie. If it isn't, it's just a matter of tracing back to find where the problem is, especially if the Leslie amp works with the UC-1A. There is a 10k wirewound resistor inside the 122 amp, and though wirewound resistors are pretty reliable, they do occasionally open up. Or maybe there's a bad solder joint at the resistor or the input plug pin 5.

    Bad connections can arc-weld themselves back together, but they will eventually burn and fail. That fits your symptoms.
    I'm David. 'Dave' is someone else's name.

    Comment


    • #3
      Well David would probably know best I would think its your run switch itself or those older run motors do/did fail. However after rereading your post I'm wondering if you are confusing the B+ with A/C mains as far as what the Leslie sends back.

      Comment


      • #4
        I had a similar problem as Hamman mentioned one time, sometimes it would come on and stay on, other times the TWG would slow down and stop after a while, and then eventually it just stopped coming on. I noticed that whenever it stopped the tubes went out too, so I checked the run switch contacts with a multimeter and they were bad. Just ordered a new one, went in easy and all is good now! Hopefully that's your problem as this was fixed very easily in my case. Good luck!
        1949 Hammond CV w/1960 Leslie 45 (converted to 145), using H-1 and Leslie 25 amp
        1958 & 63 Hammond M3
        1963 Hammond L100 with 70s Leslie 120
        1979 Rhodes Piano

        Comment


        • #5
          Thanks for your replies! I'm pretty certain it's not anything to do w/ the run motor, switch or contacts...5-6 years ago I had to replace the run motor on a CV & the symptoms were pretty different, also in this case the BC worked perfectly when I hooked it up to a JR20 tone cab, so something in the Leslie amp certainly seems to be the culprit. I was hoping the fact that the Leslie works w/ the UC-1A but not w/ the BC would be a dead ringer for a common problem, sounds like no such luck though.

          I do own a cheap multimeter, however I just moved into a new house 3 days ago and a lot of what I packed is horribly unorganized (come to think of it I don't remember seeing that multimeter when packing, or anytime in the last few years). I guess my next step is to acquire a voltmeter & investigate some connections then. I'm not particularly saavy when it comes to electrical work though...when given sufficient direction, I've been able to successfully replace bad components on many occasions in the past, but I'm still not super confident when it comes to soldering or using the diagnostic tools. So I may come back here looking for some direction on how & what to check in a few days. In the meantime, if anyone else has suggestions as to what the specific problem might be, any & all feedback would be appreciated. Thanks!
          1940 Hammond BCV
          JR20 Tone Cab
          Leslie 142
          Trek II UC-1A
          CV w/ PR40 (in process of restoration)
          Crumar Mojo
          1972 Fender Rhodes Stage 73
          Wurlitzer model 206 "student electronic piano"
          Fender guitars: Custom Shop "1960" Strat (sonic blue w/ matching headstock), MIJ Tele w/ Bigsby (sunburst, double bound), MIM P-bass
          Gretsch guitars: Knotty Pines Round-up, Jet w/ TV jones & Bigsby (white w/ gold hardware)
          Martin 000X1AE acoustic
          Amps: Fender Princeton Reverb, Vox AC15, Traynor YCV40

          Comment


          • #6
            I might have said Run Switch, too -- except that you said that the organ works fine with the JR-20 tone cabinet. That would also rely on the Run Switch and so tends to rule it out.

            There's really not much between the B+ supply in the Leslie and the organ's preamp except that one 10k resistor, some wiring, and some connectors.

            Rereading the original post, I found it somewhat unclear on whether the tone generator continues to run in all cases. The tone generator does not require B+ from the Leslie or tone cabinet.

            If the tone generator isn't working when you use the Leslie, but works with the JR-20 connected, it's a mystery.
            I'm David. 'Dave' is someone else's name.

            Comment


            • #7
              Originally posted by Johnny No. 5 View Post
              Thanks for your replies! I'm pretty certain it's not anything to do w/ the run motor, switch or contacts...5-6 years ago I had to replace the run motor on a CV & the symptoms were pretty different, also in this case the BC worked perfectly when I hooked it up to a JR20 tone cab, so something in the Leslie amp certainly seems to be the culprit.
              The JR20 probably draws less current than the Leslie; so your switch manages to pass enough current for the rig to stay running with the JR20 hooked up. With the Leslie, on the other hand, the total current demand becomes too large and the connection thru the switch fails.

              The Leslie only sends back high voltage for the AMP to the organ, not the power to run the motors.

              The run switch is guaranteed to be your culprit.
              Current organs: AV, M-3, A-100
              Current Leslies: 22H, 122, 770

              Comment


              • #8
                I'm not as certain as Enor is that it's the run switch, but the difference in current could do it.

                Since my ESR meter is basically a sensitive low-Ohms meter, I can also use it to test switches. Switch contact resistance should be very low, almost zero, and it should be consistent when you flip the switch several times.
                I'm David. 'Dave' is someone else's name.

                Comment


                • #9
                  Does the current issue mean you couldn't check it with a multimeter?
                  1949 Hammond CV w/1960 Leslie 45 (converted to 145), using H-1 and Leslie 25 amp
                  1958 & 63 Hammond M3
                  1963 Hammond L100 with 70s Leslie 120
                  1979 Rhodes Piano

                  Comment


                  • #10
                    Originally posted by Alek Z View Post
                    Does the current issue mean you couldn't check it with a multimeter?
                    No. The reason I sometimes test switches with my ESR meter is that it gives readouts in hundredths of Ohms and will spot a marginal switch contact more easily than a standard Ohmmeter where you may have 0.3 - 0.4 Ohms error just from the leads.

                    What burns up switches is resistance. Once the contact surface is damaged or contaminated, increasing the contact resistance, it heats up as the square of the current times the resistance. This heat further damages the contact surface, increasing the resistance, until it eventually burns up.
                    I'm David. 'Dave' is someone else's name.

                    Comment


                    • #11
                      Well it'll definitely be hard to figure out if it's the run switch then, aside from just replacing it.
                      1949 Hammond CV w/1960 Leslie 45 (converted to 145), using H-1 and Leslie 25 amp
                      1958 & 63 Hammond M3
                      1963 Hammond L100 with 70s Leslie 120
                      1979 Rhodes Piano

                      Comment


                      • #12
                        This BCV needed a run switch AND a run motor (chorus genny).
                        It had a tone cabinet and a 21H hanging off it for many years.
                        Should be fine with a new switch.Unlikely, but those run motors sometimes stall a few times before they fail.
                        On the A100 the run switch is original,never had a larger load on it.
                        A100/251 A100/147 A102/222 B2/142 BV/147 BCV/145 M3/145 M102/145 M111/770 L101/760 T222/HL722 M111/770 no B3/C3!

                        Comment


                        • #13
                          Replace the switch, and while you're at it do all the power wiring as well - it's a safety thing.
                          Current organs: AV, M-3, A-100
                          Current Leslies: 22H, 122, 770

                          Comment


                          • #14
                            Hey everybody, original poster here...apologies for being absent from the conversation for past week, i injured my hand to the point of it being completely useless & have still been in process of moving so haven't had time troubleshoot further. This business about the run switch is intriguing though, I had assumed that if it worked w/ JR20 but not with Leslie then it couldn't have possibly been that but I never considered the differences in power consumption.
                            Something to add though...the fact that for a while, it DID work sometimes, and often times it would turn on but die in under a minute makes me question the switch hypothesis. When it would turn on but die right away, I would never hear the TWG slowing down & lowering in pitch (which is what would happen when I had a bad run motor on a CV several years ago), instead the power would cut to the Leslie first & then I would simply hear the faint sound of TWG slowing down unamplified. Does this eliminate the run switch or motor as a problem, or could it still be the switch (only way I could see that is if the run switch is still some crucial junction point that power has to pass thru, & was just slowly failing on me)?
                            1940 Hammond BCV
                            JR20 Tone Cab
                            Leslie 142
                            Trek II UC-1A
                            CV w/ PR40 (in process of restoration)
                            Crumar Mojo
                            1972 Fender Rhodes Stage 73
                            Wurlitzer model 206 "student electronic piano"
                            Fender guitars: Custom Shop "1960" Strat (sonic blue w/ matching headstock), MIJ Tele w/ Bigsby (sunburst, double bound), MIM P-bass
                            Gretsch guitars: Knotty Pines Round-up, Jet w/ TV jones & Bigsby (white w/ gold hardware)
                            Martin 000X1AE acoustic
                            Amps: Fender Princeton Reverb, Vox AC15, Traynor YCV40

                            Comment


                            • #15
                              Intermittent stopping leads to a faulty run switch most of the time.
                              We have already 'troubleshot' this.
                              Assuming your hands work well enough to operate an DVM
                              and soldering pencil?
                              Replace the switch.
                              A100/251 A100/147 A102/222 B2/142 BV/147 BCV/145 M3/145 M102/145 M111/770 L101/760 T222/HL722 M111/770 no B3/C3!

                              Comment

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