Burning Amp

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by gldtp99, Jun 11, 2019.

  1. gldtp99

    gldtp99 Member

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    George from Metro replied to this vid and told him:

    1) The amp was a DIY kit, sold by Metro, and not built by Metro themselves.

    2) The tube socket needed to be replaced because of the arc event.

    What do you guys think about all this ?
     
  2. 0010 0001 0011 1111 1110

    0010 0001 0011 1111 1110 Member

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    Point 1, no opinion.
    Point 2, I concur.
    I watched that video earlier today and I have to say, as good of a player Brad is, the amp sounded quite a bit off. The gain sounded, hmm, not smooth?
     
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  3. HotBluePlates

    HotBluePlates Member

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    When the camera zoomed in there did not appear to be carbonization across the body of the socket for future arcs to follow. One could argue the absence of that carbon trail means the socket did not need replacing, especially since we know it was tech-error that created the arc.

    OTOH, the pins themselves & solder on pins 2 & 3 were carbonized, and needed at least some cleaning with alcohol & perhaps reflowing. And a burn mark was left on the 1kΩ screen resistor for that socket. Worse, the insulation on the heater wire running to pin 2 was partly melted. It wasn't clear in the video any of those things were addressed (I saw the burn on the screen resistor late in the video, so that wasn't fixed), and they should be because they are tech-caused defects that didn't exist in the amp when it arrived. They are items that could cause future issues; any tech should fix damage they caused at no charge, and consider it the price of a lesson on what not to do.

    This video shows exactly why many times I kill B+ in an amp before moving probes on output tubes. I learned that lesson the hard way myself.

    Separate items I didn't like was "checking bias voltage" at the board. I believe it should be measured right at pin 5 if one is going to check, because there's no guarantee the wiring/soldering is good. And, if the amp is popping fuses & burning up a tube why not check B+ with no output tubes installed first?
     
  4. gldtp99

    gldtp99 Member

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    Yes, there have been many things in the vids made by this person that I question.

    I realize that I don't know it all but I don't agree with all the procedures I've seen, and the thinking process behind them, that I've seen in these vids.

    But he seems to be held in high regard by many people.

    I wondered if I was just being too critical ?
     
  5. slider313

    slider313 Silver Supporting Member

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    That's not a burning amp.............this is.....:D

     
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  6. Steppin' Wolfe

    Steppin' Wolfe Member

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    Just a personal observation, but the tech in that video is working from the wrong side of the chassis, imho. I was taught and prefer to work from the back side of the chassis. Since I started studying Fender schematics and layouts before working on amps and since the very experienced tech whom I watched some while he worked on amps approached the work from the back side, that seems natural to me. Working from the back allows one to see the front panel controls, jacks, etc as well as presents the layout to me in a more workable manner. Ommv....
     
    slider313 likes this.

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