Vintage Super Lead 100 Problem, Please Help!!!

Discussion in 'The Workbench' started by Frank Plante, Dec 23, 2018.

  1. ampmadscientist

    ampmadscientist Well-Known Member

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    This type socket is a special type that was only used in 1971 (I do believe).
    This socket has a metal retainer (snap ring) ring around the socket.
    This socket has a flange plate which is removable.
    The chassis cutout diameter of this socket is 1.25" or 31.75 mm, is larger than a normal Marshall socket.
     
    Last edited: Dec 25, 2018
  2. Frank Plante

    Frank Plante New Member

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    Alright! I'll be able to attempt this with him in about a week or 2, let's hope it works! Thanks for your help, if the problem persists I'll come back here thanks again
     
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  3. ampmadscientist

    ampmadscientist Well-Known Member

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    There's several things you need to do including checking your speakers, speaker cables, jacks, impedance selector plug.
    Any of those can make the sockets arc.
     
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  4. Frank Plante

    Frank Plante New Member

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    I have already checked all those and they are working correctly, maybe it wasn't used properly in the past? that would be my best guess. Speaker cab is wired correctly, the speaker cables are new, amp head is set on 16ohms (i have a 4x12, and the back of the speaker indicate 16ohms) . What do you think about the filter caps failing? Would that cause that kind of problem?
     
  5. m1989jmp

    m1989jmp Active Member

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    I'd say change the filter and bias caps regardless; they're cheap enough and can cause a lot of expensive failures when they finally fail.
     
  6. ampmadscientist

    ampmadscientist Well-Known Member

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    The tube sockets arc because of impedance mismatch.
    Then if the sockets are burned they need to be changed.

    Mismatch can happen if the impedance selector plug in the back of the amp is worn out....making intermittent contact. (this selector plug is a weak point which fails)
    A bad speaker cable.
    Bad connections inside the cabinet.
    Bad speaker jacks that no longer make good contact.
    Blown speakers (speakers that scrape when they move in/out).

    Or any of this could have happened long ago. Before you owned the amp.

    Any socket which is burned must be replaced.
    The screen grid resistors must be changed (at least 2 of them look burned).
    The speaker must be matched to the amp.
    The bias must be adjusted correctly.
    The output tubes must be good (if these have not been damaged).

    The capacitors do not cause sockets to arc.
    But if the caps are old, you should change them. Those can fail from age.

    1. Connect a speaker cable to the cabinet.
    2. Connect an ohm meter to the end of the speaker cable.
    3. What is the reading? This is really important.
     
  7. ampmadscientist

    ampmadscientist Well-Known Member

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    "...a sort of loud static-like sound when I play..."

    Yes I see why - because the sockets are arcing / sockets resistors are burned.
    All this stuff must be corrected before you play the amp again.

    Where are you located? I'm going to maybe recommend a tech.
     
    Last edited: Dec 24, 2018
  8. Frank Plante

    Frank Plante New Member

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    I am located in Quebec City, in Canada. Do you know where I could buy the sockets? I want to be sure I buy the right thing, especially if they are a special type.
     
  9. ampmadscientist

    ampmadscientist Well-Known Member

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    Can you get a better picture of that socket? I can't see it very clearly, where it looks like it burned.
    Do any of the other sockets have burn marks?
    I need to see who has those bigger sockets in stock. Yes somebody will have some...

    1959SOCKET.png
     
  10. Frank Plante

    Frank Plante New Member

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    Sure, does this help?
     

    Attached Files:

  11. ampmadscientist

    ampmadscientist Well-Known Member

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    It's not the same brand as original, but it fits the (oversized) hole. It's made by Amphenol or Millen.
    It has a retainer ring and a mounting flange that holds it together.

    [​IMG]

    https://www.ebay.com/itm/AMPHENOL-8...h=item25f62d50de:g:1nIAAOSwHhRa9ku~:rk:5:pf:0

    [​IMG]

    1959retainerring.png

    [​IMG]

    This is Millen socket 33008, I have used it in these amps before because it fits the over-sized hole.
    Millen 33008 Steatite octal tube socket flange for 1.25" / 31.75 mm diameter hole
    1.625 center-to-center mounting holes.
    Bottom mount, mounting flange can be removed so it can mount in the same keyed holes as Amphenol 78/86 series.

    millen octal bottom.png

    millenoctaltop.png
     
    Last edited: Dec 25, 2018
  12. ampmadscientist

    ampmadscientist Well-Known Member

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    On this one socket pin 2 is definitely arcing to pin 3.
    You need to replace at least this 1 socket.
    Do any of the other sockets look burned? check really carefully for any other burned spots.

    1959 toasted.png

    1959toastedpuppy.png
     
  13. Frank Plante

    Frank Plante New Member

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    Thanks, do you suggest I change all 4? If so, is there another post that sells 4 of them? I believe I saw a guy that sold 4 black ones in the tab
    "People who viewed this item also viewed" , but again i cant post a link down here.
     
  14. Frank Plante

    Frank Plante New Member

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    I will check and attach more pics
     
  15. Gutch220

    Gutch220 Well-Known Member

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    Could this type of arcing be caused by somebody erroneously turning on the amp without a speaker load? I bet a lot of people do this.
     
  16. ampmadscientist

    ampmadscientist Well-Known Member

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    Check around to find 4 clean ones....but so far only 1 is really bad.
     
  17. ampmadscientist

    ampmadscientist Well-Known Member

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    yes that is possible

    but usually set amp 16 ohms, hook up 4 ohm cabinet is what does it.
     
  18. ampmadscientist

    ampmadscientist Well-Known Member

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    The black ones are plastic, which are not as good as the ceramic ones.
    So if you can find ceramic for a 1.25 inch / 31.75 mm hole that would be better.
     
    Last edited: Dec 24, 2018
  19. Gene Ballzz

    Gene Ballzz Well-Known Member

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    @Frank Plante
    You said you checked that your speaker cables are good, but no asked if they are actual speaker cables or shielded cables? If shielded, this must be corrected! You also have not answered the question about the "measured" DC ohms resistance of your cabinet? Should read 12Ω to 13Ω-ish, for a 16Ω cabinet.
    Just Sayin'
    Gene
     
  20. ampmadscientist

    ampmadscientist Well-Known Member

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    Or it could have happened before he bought the amp.
    (impedance mismatch)

    But he should test all that stuff anyway to be on the safe side.
     

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