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Thread: What does it take to break a tube pin?

  1. #1
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    What does it take to break a tube pin?

    I broke a pin on a 12AX7 yesterday while installing it in a socket. I removed and replaced a dozen or more tubes yesterday in the very same socket while testing some tubes I just bought.

    I have swapped hundreds of tubes in the past. I have never saw a pin break... ever.

    I'm trying to explain to my vendor that I feel I was being gentle and that I think that the tube had some type of defect. I don't think he agrees. So I'm probably stuck with an expensive NOS tube that is useless.

    This has got me wondering... what WOULD it take to break the pin on a healthy tube? I never thought about it but I imagine that it takes some specific effort to break a pin... even if you intend to do so.

    Does anyone have any thoughts about what it might take to break a normal pin?

    Thank you.

    best regards,
    mike

  2. #2
    Supporting Member Jazz P Bass's Avatar
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    The tube pins are typically a soft metal.
    Not a hardened steel.
    Where did it break?
    Flush with the glass?
    I have seen pins bent over flat with the glass & they could be pulled back straight.
    Obviously this stretches the metal at the bend.
    Being a soft metal it can be flexed to a degree.
    Could be a metallurgy thing.
    Then again if it is a stainless type steel, being harder it may crack.

  3. #3
    Supporting Member Chuck H's Avatar
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    Never broke a pin. I think your right but that doesn't matter. There's no way to prove you didn't break the pin by abusing it and it is an old tube that was sold to begin with. I don't see a good way to fight this except to go with another vendor from now on. One that would recognize the rarity of this kind of thing and not take advantage of the gray area in the details.

    Chuck

  4. #4
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    Thank you for offering your opinions.

    best regards,
    mike

  5. #5
    Senior Member Howlin' Mad Mac's Avatar
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    If you didn't already have a conversation with the vendor about it, you could always order another tube of the same make & model & when it arrives complain it "arrived" in that condition & you want to return it for a replacement. Yeah, you'll have to purchase an extra tube but at least you won't be stuck.
    Hey you... Yeah you kid... Ya wanna buy some "Magic Beans"?

  6. #6
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    I will not consider doing that.

    I am frustrated that this vendor doesn't seem at all prepared to consider the idea that I am honest and that my claim is legitimate... he got the last $40 he's gonna get from me... I now know that we can not continue doing business together.

    best regards,
    mike

  7. #7
    Senior Member melvin's Avatar
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    At least tell us who the vendor is.

  8. #8
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    In my book, which might be wrong, of course, the only thing which might break a tube pin is fatigue, and that would come only from a pin that was bent and straightened a few times before, leaving the metal weakened. Add to that some crack aready present which you didn't see (nor imagine it would be here).
    That so-called NOS tube should really be called UOS or VUOS, meaning used old stock or very used old stock, very probably "pulls" from old equipment.
    Where else could the inexhaustible EBay supply come from?
    Sorry.

  9. #9
    Senior Member Pedro Vecino's Avatar
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    J M Fahey is right. One reason is the bent and straightened of the pins in used tubes, but some old tubes are more sensitive on the issue and today some sockets pins are stronger than previously. Knowing the exact tube model and amp model can determine whether higher or lower is the risk (understood as a new tube)
    For example: on Mesa amps the cover springs generate much tension. Current Russian and Chinese tubes support well, but using old tubes this tension should be reduced cutting it.

  10. #10
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    Yes I understand what you are saying... it seems we all agree it would take repeated bending cycles.

    This tube was an Amperx 12AX7 Made in Germany possibly by RFT.

    It and the other one I bought seem to be true NOS. The tubes and boxes are reasonably clean.

    I just got a bad example and the vendor is treating me as if I am trying to pull something over on him.

    I have bought over a thousand dollars worth of tubes from him over the past fifteen years and he is choosing to stand his ground and treat me like I am lying about how the damage occurred. The darn pin just popped off while I was inserting it.

    I am a bit put off that after so much good will and profitable business... he's going to spoil our relationship over what ever he made on this $40 tube... by essentially treating me as a liar and a cheat.

    Thanks for sharing your opinions.

    best regards,
    mike

  11. #11
    Supporting Member Chuck H's Avatar
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    Welcome to the information super highway... Your name is a $ sign and nothing more. Eventually some standard of courtesy and compensation vs. recognition of a regular client will be handled by software designed to maximize profits by making regular clients feel important. Until then we're at the mercy of raw human nature. Make your $ and "who cares who you are, I made my margin and never actually read your name on the forms".

    Sorry

    Chuck

  12. #12
    Noodle of Reality Steve Conner's Avatar
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    I got a few of those Belton sockets for a recent build, and they have huge spring tension. I really had to shove the tubes in, and I could see how that might stress something.

    Used old stock tubes are fine by me. I have a great collection that I raided from old industrial and lab equipment on its way to the scrap heap. My finest find was 7 GEC KT88s, from which I managed to make two matched pairs.

    I don't know how much they would go on Ebay for, unless I dishonestly sold them as NOS. I'm not prepared to do that, so I'll probably be forced to just use them up in my hi-fi system, what a bummer
    "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"

  13. #13
    Supporting Member Chuck H's Avatar
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    Quote Originally Posted by Steve Conner View Post
    I don't know how much they would go on Ebay for, unless I dishonestly sold them as NOS. I'm not prepared to do that,
    Good for you. There's a lot of that around. Some sellers use NOS as a descriptive term when they are selling pulls. I think the distinction is waning and NOS is starting to be interpreted as 'good old tube' rather than new old stock. The price difference is shrinking also so you could sell them honestly and make some $$$. But then YOU wouldn't have them.

  14. #14
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    I've broken one but this was on a tube that already had the pin extremely bent(trying to bend it back into position). Still worked though (one side of it anyway--this was on a small 6AL5 rectifier tube).

  15. #15
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    I've broken a pin just by knocking the amp over. Yes, it was clearly a defective pin. No, I did not bend the pin or repeatedly insert the tube in the socket. It was almost certainly a bubble or fracture in the pin itself introduced during manufacturing.

    Luckily, it was a cheap Chinese tube that was neither expensive nor costly to replace. However, it did take a long time for me to figure out that a broken off pin was stuck in the tube socket, and the socket had to be replaced. Also lucky for me was that the socket was inexpensive to replace.

  16. #16
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    I had a nice thing occur that sort of made up for this situation... I just bought and scrapped an old organ with 31 long black plate RCA 12AX7s dated 1957.

    :-)

    Somehow it sort of evens out.

  17. #17
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    Well, now you know why it's a:
    it was a cheap Chinese tube

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