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Thread: M3 rattling hum when when turning on. I'm stumped

  1. #11
    ppp Pianississmo Escape pod's Avatar
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    Thanks Seet Peet for the speedy reply, I checked the swell cap inside for shorts or loose wiring it looked really clean and everything in order. So on to the matching transformers and I am assuming the switch plates you are referring to is the controll panel by the registers. What exactly should I be looking for loose wires etc and dendrites. I guess I should just give the panel a good cleaning. How do you think I should go about testing T1 and T2 I'm open for suggestions and things to stay away from. Thanks again everyone on this forum has been great

  2. #12
    fff Fortississimo blhristov's Avatar
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    Tripple check the ecaps you replaced. If the amp was moderately working before, you may have miswired something. Check against the schematic of your amp type available online.

  3. #13
    f Forte muckelroy's Avatar
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    It seems like your amp is mostly-silent when grounding its inputs. That's a good sign.

    To test the organ signal separate from the amp, remove all tubes from the amp so that it is not conducting (You can remove the 5U4 only, if you are OK with the rest of the tubes glowing. They shouldn't conduct any high voltage though.)

    Disconnect the yellow and green wires from the "A" terminals of the AO-29. Then, find a separate preamp, or amp. Any small guitar amp will do. Get a 1/4" cable, run it into your guitar amp. Connect the "tip" lead of the other end of the cable to the yellow cloth-covered wire that normally would connect to "A" terminal of the amp. Attach signal ground to the braid shielding/ground of that cable. Start the organ. You should hopefully hear normal organ signal as long as vibrato is turned off. Now power off, and switch your hookup to listen to the "B" green wire. Test how it sounds when vibrato is turned on.

    If this sounds anything less than ideal, your problem lies upstream (either the matching transformer, control panel, or a ground somewhere along the way.)

  4. #14
    ppp Pianississmo Escape pod's Avatar
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    First of all I'm sorry I misspelled your name Sweet Pete I need to review my posts better. So Muckelroy I did the guitar amp test and the organ sounds great through the amp on both tests. I'm assuming that means it is in the the organ amp itself this is good news but puts me back where I started. If correct on this I will go back through the circuit wiring again but with a more confident and discerning eye as that is where the problem is. Any other advice is greatly appreciated

  5. #15
    pp Pianissimo wannab3's Avatar
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    Did you use the recap kit from Tonewheel General Hospital?

    Can you post any pictures of the inside of the amplifier chassis?
    1955 Hammond M3 & 1960 Leslie 45 (2 speed via MTCLogic)
    Work in progress: 1962 Hammond A100
    I chose a terrible user name.

  6. #16
    ppp Pianississmo Escape pod's Avatar
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    Yes, I did get it from TGH. I will post some pics when I get home.

  7. #17
    ppp Pianississmo Escape pod's Avatar
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    IMG_0090.jpgIMG_0089.jpgIMG_0088.jpgIMG_0085.jpgIMG_0087.jpg

    - - - Updated - - -

    Let me know if these pictures are detailed enough if not let me know exactly what to shoot
    and as always
    Thank You All

  8. #18
    ff Fortissimo Sweet Pete's Avatar
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    The grey e-cap in picture 3 is C14?
    Had trouble with mine as well.
    Schematic says 30uf/25V and I ended up using a 33uf/50V. 22 seems a bit off course....
    Try reflowing those solder joints where you've replaced the resistor (dark blue cable) as well.
    The one I recapped (a '57) had issues after the rebuild. I ended up back in there reflowing solder.
    No issues since then with it!
    A100/147 B2/147 A102/222 M102/145 M111/145 L133/770 1937 Northern Hammond(third one built) BCV/122 NordStageEX88 Yamaha MOX6,Neo Ventilator
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  9. #19
    ppp Pianississmo Escape pod's Avatar
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    Hi,
    yes the grey e-cap is c14 provided by tone generator hospital it is a 100 MFD 35v connected at pin 3 to ground. I reflowed the solder joints on the resisters as well. If you or anyone else sees anything of interest
    please let me know.
    and again
    Thank You

  10. #20
    ppp Pianississmo Escape pod's Avatar
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    Hi All, well I thaught I would get back to everyone after a long work week. I was able to get the M3 working I found a faulty ground connection as well as a couple of sketchy component connections on my meter. At first the vibrato on did not work but then it kicked in and has been working ever since. I hope that doesn't become an intermident issue but for know all is well.
    thank you all for your insite, experience sharing and helping me through this I learned a lot from all of you.This is such a great community of people
    I hope I can return the favor to someone in the future.
    EP
    Michael

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