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  • Hammond M3- No sound

    Hi everyone. This isn't quite like all the other stories of "This hammond hasn't run in 20 years" and then it just needs oil or they don't know how to start it. I use my M3 several times a week and it was working fine until about a week ago. I turned the organ on its side for bass pedal maintenance which I'd read was acceptable. I put rags at the oil cups to prevent oil from dripping everywhere. When I got it back on the ground it turned on but failed to produce sound. I had swapped the position of the two 6v6 tubes about a month earlier which solved a low frequency hum I'd had, so when this new problem occurred I thought of those tubes. I brushed off the ends of the tubes and put them back in their original positions. Problem solved . . . for a while. The problem has since happened increasingly often where I'd start the organ- no sound, maybe wiggle the tubes and get sound back until I found some old 6v6's from my guitar amp. They worked but after they run for a few minutes the volume decreases and it starts to get some deep purple style overdrive, but I figured its only temporary (and maybe a little fun). The distortion increases with the amount of notes played and really comes out in the low end. This led me to believe that it might be a rectifier tube. I still would occasionally turn the organ and get no sound. To make things more complicated I then wired a connection to a leslie 125 I just got through a 26-1 connector box and disconnected my original speaker. After about a day using my Leslie with the same problems it finally stopped producing any sound.

    At this point theres so many factors I'm not sure whats to blame. I've replaced the rectifier, 6v6's, 12ax7, and 12au7. In addition I also used deoxit on all the sockets and poked through the holes with a guitar string. They all light up just fine. The only one left I'm considering is the second tube that goes to the pedal. I had oiled the organ not long beforehand and I heard that oil can drip right onto that tube. I'm not super experienced with working with this stuff so I just peeked under the amplifier without touching anything and nothing was obviously burnt out (atleast not to my eyes). I checked the connections on my 125 and everything looks good. It spins and switches as it should.

    Any thoughts? I don't know what to think at this point. I really thought it was tubes, but now I'm not so sure. Any suggestions help.
    M3 w/ Field Coil
    M111A 1967
    M2 (Gone)
    Leslie 125 W/ Amp 1963

  • #2
    Check the output tube (6V6) bias. The negative DC bias voltage is known to fail. Tubes would overheat and distort without it.

    Geo

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    • #3
      Thanks for the response. Sorry I'm just getting back now. I was snowed in with no internet for a couple days there.

      Anyways, I'm a bit familiar with doing the bias for tubes on a guitar amp where you might have a pot to adjust it, but how would I go about adjusting it on an M3? Are you saying that the resistor that regulates bias is gone? Sorry if these are dumb questions, but I'm still learning my way a bit with working on these organs.
      M3 w/ Field Coil
      M111A 1967
      M2 (Gone)
      Leslie 125 W/ Amp 1963

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      • #4
        Do you have the service manual and a meter? The bias voltages derived from the PS are -22 and -19. The -22 is used in the base pedal amp and is on terminal X.

        Jim

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