Do I need a new Transformer?

Discussion in 'Amps and Cabs' started by piloto117, Feb 20, 2012.

  1. piloto117

    piloto117 Member

    Messages:
    311
    Joined:
    Jan 24, 2012
    Hey guys, wondering if you can help me pinpoint a problem I'm having with my amp.
    It's a Fender Blues Deluxe RI. I've noticed that playing around an hour, the volume drops a bit; recently it's been happening on a shorter time. Not only does the volume drop a bit, but there's a hum present when I'm plugged in, which is my main concern/problem. If I unplug the cable, the hum is reduced to almost nothing/normal, but still present. With some pedals connected inbetween and engaged (especially distortion pedals) the hum is louder. I also lose some highs and the amp behaves and responds differently when this occurs. I've placed a fresh set of power and preamp tubes with proper bias, and other than the speaker, the amp has no mods at all. I've been trying to do some research and I'm starting to suspect that the power transformer may be wimping out, as it does get pretty hot when this problem starts to happen. Could this be it?
    Any suggestions?
     
  2. Blue Strat

    Blue Strat Member

    Messages:
    30,036
    Joined:
    Aug 2, 2002
    Location:
    Sterling, VA (not far from Washington DC)
    Transformer problems virtually never happen and almost always present themselves as the amp not working at all.

    If the amp doesn't hum with nothing plugged in, the problem is outside the amp. If you're using single coil pickups and/or you have florescent light lights in the room (or are playing close to the amp) that is at least part of your problem.
     
  3. piloto117

    piloto117 Member

    Messages:
    311
    Joined:
    Jan 24, 2012
    No, the problem isn't outside the amp. When I unplug the cable, the hum is ALMOST gone, but STILL present. I've tried different configurations with pedals, cables and guitars and they're not the problem. I'm using a Furman power conditioner as well, trying to isolate RF and such, but that is not the problem either. If it were, I'd be listening to the hum all the time. This is not the case, the hum comes when I've been playing for around an hour straight or so, also with a slight volume drop.
    Let me put it another way, if I were to hear any problems with a transformer; what would it sound like and/or be expecting?
     
  4. solitaire

    solitaire Senior Member

    Messages:
    3,721
    Joined:
    Jan 31, 2006
    Location:
    In the heartland of Sweden
    Judging by the symptoms you describe I would have guessed it was an output valve that's on the blink. Had that happen to me in the past.
     
  5. nospickups

    nospickups Silver Supporting Member

    Messages:
    582
    Joined:
    Dec 6, 2009
    +1 on this, I had the same prob with an amp and it was one of the preamp tubes. Try replaceing those one by one with a known good one to find the bad one or rule it out as aproblem.
     
  6. piloto117

    piloto117 Member

    Messages:
    311
    Joined:
    Jan 24, 2012
    Unless I have a defective tube, but like I said; I've replaced them with a fresh set of both power and preamp tubes and have biased them correctly.
    The problem with the hum is still present (before and after the tube swap).
    I'll try to swap them around again, one by one see if that's the problem. Still, I'd like to know if I were to have a transformer problem, what would I be expecting?
     
  7. piloto117

    piloto117 Member

    Messages:
    311
    Joined:
    Jan 24, 2012
    Well, I went thru 3 different sets, one by one. The first combo that worked well only did it for like 2 minutes, it started to become extremely noisy and then the sound went off completly. I went thru all my tubes and now I can't get any sound from my amp. Apparently, everything lights up as it should but no sound at all. If i softly wiggle the V1 preamp tube i get a little "crumbling" sound and that's it. One pair of power tubes got fried when the distorted noise was coming thru.
     
  8. piloto117

    piloto117 Member

    Messages:
    311
    Joined:
    Jan 24, 2012
    OK, got it working again. I remembered something I read somewhere saying that these amps are common to have these issues with hum caused by a bad contact on the soldering pads on the PCB. Since the tube sockets are inverted, the heat from the tubes can/may cause a weak solder joint to break contact. So I reflowed each and every one of them and I got it working again. Still need to see if that took care of the hum though. Thanks anyway, you were right, I had a new but defective tube in V1.
    Still want to know, problems with transformers....lol, but I guess I'll post a new thread!
     

Share This Page