NAD gone bad. Orange Root Terror

Discussion in 'Amps & Cabs' started by ypnos, Aug 25, 2018.

  1. ypnos

    ypnos Well-Known Member

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    Bought this amp for 350 euros, which is a great deal considering everything goes well.

    The amp is a 15 watt beast. Delivers hard rock and desertlike tones, but in a really agressive manner.

    Hooked it up yesterday first time, but.... The amp stopped working for like less than a second, for 3 or 4 times at the beggining, randomly, an then stopped doing it. Thought it was some not well connecte cable.

    That was not the issue as it turned out. Today the amp was not usable. Continuous blackouts. :(

    The amp is played in a band situation rehearsing, volume wise maxed out and gain around 4.

    Has three preamp tubes, but two of fhem seem to glow inside the metallic socket that protects them. Could this be it? A failed preamp tube?

    Also the tube that runs the effect loops seems not to be glowing too.

    Need help

    [​IMG]
     
  2. Chubbles

    Chubbles Well-Known Member

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    Tubes can be a fickled thing. They do go bad, especially with used amps.
     
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  3. Clifdawg

    Clifdawg Well-Known Member

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    Any chance you could snap a photo of the tubes when the amp is on and warmed up? That could help in diagnosing the issue.
     
    Dale likes this.
  4. ypnos

    ypnos Well-Known Member

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    I'll do it as soon as i can, mister
     
  5. syscokid

    syscokid Well-Known Member

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    All vacuum tubes have heater filaments that will emit a small orange and warm glow when the amp is on... even on Standby mode. Some preamp tubes have their heater filaments so well encased in their plates, that it's hard to see the glow. Use a dark room and see if you can see the effects loop tube glow.

    If any of the power tubes have a big and bright orange-red glow, then they are red-plating and might be permanently bad:

    red_plating_power_tube.jpg

    Your amp has 6 tubes in total. 2 EL84 power tubes, 3 12AX7's for the preamp and phase inverter circuit, and 1 12AT7 for the effects loop. I would start by checking those power tubes first. In fact, do you have a source that can test all the tubes? It's always a good idea to have spare or extra tubes that you might need, just in case!
     
    Clifdawg likes this.
  6. DaveInSoCal

    DaveInSoCal Active Member

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    I would suggest re-seating the tubes since the problem was initially intermittent, I'm guessing it could be one of the EL84's since everything blanks out. I'm no tube expert but that's what I would do first. If you can get access to a tube tester that's the best way to go.
     
    Last edited: Aug 27, 2018
    Dale and syscokid like this.
  7. ypnos

    ypnos Well-Known Member

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    Decided to get it to the tech. In case the problem is somethjng else rathen than tubes, it'll be returned.

    Thanx all for the replies, by tomorrow i'll post more details.

    Hope it's just the tubes, i really like this amp.
     
    TubeStack likes this.
  8. tbonesullivan

    tbonesullivan New Member

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    Good luck! Tubes really can be fickle. Also if it was shipped, they can be not properly seated in the sockets.

    Was this a new amp, or used?
     

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