1974x power tranny replaced not good

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by toneseeker, Aug 1, 2006.

  1. toneseeker

    toneseeker Member

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    I have a hw 1974x that is 1 year old . The power transformer blew. I had a Marshall tec replace and repair the amp. The replacement transformer from Marshall is not the same as what came with the amp originally. I think it has changed the tone of the amp and I don't like it.
    Have any of you had this happen ?
     
  2. John Phillips

    John Phillips Member

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    Yes. I had a '90s Vox AC15TBX - built by Marshall - on which the PT blew (for no very obvious reason... the amp was actually on standby at the time). I had a factory replacement sent from Marshall, which turned out to be a Dagnall - the original was a Drake. I don't think it sounded as good after that, even though it was the only component changed, and I didn't keep the amp.

    I've replaced a lot of recent Marshall transformers professionally, and the replacements are often slightly different from the originals (and usually Dagnalls in place of Drakes) but that's the only one I've been able to compare the tone of before and after, since the other ones all came to me dead.

    I would hope they are changing the spec on the transformers, because they are beginning to have a very poor reputation for reliability, and they really need to do something about it - but the downside is that it probably will affect the tone.
     
  3. Geetarpicker

    Geetarpicker Member

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    My 2 years+ old 1974x recently cooked the power transformer. I got a new one from Marshall that was an upgraded part, about 1/4" thicker core. I didn't notice any difference in tone however the new transformer also blew out after only about 1 hour on it. Currently I'm waiting for a second replacement from Marshall. I might just get a Heyboer transformer and be done with it. It's interesting that my amp worked fine for about 2 years of pretty hard use (always on 10) before the first transformer cooked. It goes without saying that many of these amps may make it passed the warranty period only to blow out a few years later. Not that transformers can be expected to last forever, but it's a shame Dagnal (Marshall's supplier on these) doesn't have it together with these yet...
     
  4. slider313

    slider313 Silver Supporting Member

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    I have a '61 brown Fender Vibrolux,Concert,'64 Vibrolux Reverb,Pro and a '65 Deluxe Reverb,a '61 Martin 112 and a '63 Gretsch Dual Twin;all with original tranny's. 40-45 years is not forever,but I'm sure they'll be working just fine long after I'm gone!!
     
  5. John Phillips

    John Phillips Member

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    Transformers absolutely can be expected to last 'forever', in electronics terms anyway - at least as long as any other component in the amp including the chassis. If they're properly spec'ed and the insulation does not burn through, they're not loaded wrongly, and they're not subjected to moisture causing corrosion, there is nothing that will stop a transformer continuing to work indefinitely.

    The problem is that Marshall aren't spec'ing them correctly... it's that simple.
     
  6. mockoman

    mockoman Member

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    So the power tranny DOES affect the tone?
     

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