Nasty hum in my '74 V4B

Discussion in 'Amps and Cabs [BG]' started by MichelD, Apr 17, 2019.


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  1. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    Sometimes, it's less expensive to ship the amp to a tech who really understands these amps. Alternatively, if you can wait until things get better, perhaps a road trip might be an alternative?
     
    bobyoung53 and Sunnampeg like this.
  2. Sunnampeg

    Sunnampeg

    Nov 11, 2019
    UK
    the amp is from the technician
     
  3. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    I am talking about a tech who REALLY understands these amps, not the technician that you have been having these experiences with.
     
    bobyoung53 likes this.
  4. Sunnampeg

    Sunnampeg

    Nov 11, 2019
    UK
    yes i brought the amp to the Guilford guy who also restore vintage ampegs
     
    bobyoung53 likes this.
  5. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    A different tech than the one(s) before? Maybe that wasn't clear?
     
  6. Sunnampeg

    Sunnampeg

    Nov 11, 2019
    UK
    yes exactly
     
  7. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    Gotcha, I missed that detail then.
     
  8. Sunnampeg

    Sunnampeg

    Nov 11, 2019
    UK
    amp is done and there was a fault on the caps they were to old and also on the circuit board resistors near v1 v2
     
    Wasnex, bobyoung53 and beans-on-toast like this.
  9. TomB

    TomB Supporting Member

    Aug 24, 2007
    Vermont
    So the problem is solved?
     
  10. MichelD

    MichelD

    May 19, 2014
    I've got a sizzling sound in mine that sounds like someone is frying bacon in there.
     
  11. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    More often that’s a sign of a bad pre-amp tube.
     
  12. MichelD

    MichelD

    May 19, 2014
    Crazy. Just had it in the shop and he replaced all the power tubes and one preamp tube. He must have tested the one he left in and found it good I guess.
     
    beans-on-toast likes this.
  13. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    OR, the shop never identified the actual cause of the problem?
     
    BassmanPaul and turcmic like this.
  14. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    I did say that most often it is a preamp tube but there are many other possibilities. Since tubes were changed, it could be that a new tube has smaller pin diameters which leaves the socket contacts loose. In that case, retensioning the socket will resolve the issue. there are other possibilities if that isn’t the problem.

    Unfortunately, it looks like another trip to the tech.
     
  15. Sunnampeg

    Sunnampeg

    Nov 11, 2019
    UK
    its less noisy than before..not like my Sunn 2000S but it s decent..i m very happy I ve an amp with an Amazing tone.
     
    TomB and agedhorse like this.
  16. BassmanPaul

    BassmanPaul Inactive

    If coming back from the tech you are not happy with the unit take it back to him to fix properly!
     
    Fishheadjoe likes this.
  17. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
    Aug 4, 2021

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