1. You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
    Dismiss Notice

Sometimes you just can't trust your lyin' eyes. NCL2000 crock.

Discussion in 'Amplifiers' started by nomadradio, Nov 27, 2018.

  1. nomadradio

    nomadradio Analog Retentive

    Joined:
    Apr 3, 2005
    Messages:
    1,970
    Likes Received:
    1,404
    Sometimes you just can't believe your lyin' eyes.

    This resistor should have a green third band, as in "brown-black-green".

    But somebody looked at the old one after it had overheated and burned that green band black.


    [​IMG]


    Before you replace a resistor with a black third band, consider what color it used to be, especially in tube-type equipment.

    This resistor is in a National NCL-2000 amplifier. It serves to shut the amplifier down in receive mode. One section of the antenna relay shorts across it when the amplifier is keyed, activating the tubes. This 10-ohm part would have caused the tubes to cook along at full idle current on standby and when keyed, both. Sure would have caused it to run hot even if you never keyed it. The correct 1-megohm part blocks the voltage to the screen grids of the tubes, and puts them in standby mode.

    And I probably would not have noticed it if Kopcicle hadn't asked about this section of this model amplifier. I suppose dumb luck is better than bad luck.

    73


     
    sunbulls and Shadetree Mechanic like this.

  2. Low_Boy

    Low_Boy Well-Known Member

    Joined:
    Jan 21, 2010
    Messages:
    735
    Likes Received:
    215
    Good catch
     
  3. Handy Andy

    Handy Andy Do Your Research First, Then Decide...

    Joined:
    Apr 23, 2018
    Messages:
    1,587
    Likes Received:
    1,310
    Wow! It' literally looks like a 10 ohm OEM part.

    1 Meg eh?

    Good to see you on the job!
     
  4. kopcicle

    kopcicle Sr. Member

    Joined:
    Feb 17, 2016
    Messages:
    635
    Likes Received:
    621
    ...your welcome. More like even I stumble across something once in a while :ROFLMAO:
     

Share This Page

  • About Us

    The WorldwideDX Radio Forum was originally established in 2001. We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. We are working every day to make sure our community is the best Radio Hobbyist's site.
  • Like us on Facebook

  • Premium VIP Member

    The management works very hard to make sure the community is running the best software, best designs, and all the other bells and whistles. Care to buy us a beer? We'd really appreciate it!

    Donate to us!