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Thread: Arcing

  1. #1

    Default Arcing

    I'm scared. My HP 54111d oscilloscope starting acting up a couple of weeks ago. I turned it on for the first time in say a couple months, maybe longer, and I heard a popping, so I turned it off. A week or more later I turned it on again, and it popped to the degree that the display wobbled significantly. I've been leaving it outdoors on sunny and windy days, thinking maybe humidity over the summer needed to dry out
    But I don't want to turn it on again, until I can be sure what the problem is, and know the issue is resolved. I'm afraid I'll blow the little Sony crt unit and I'll be pissed.

    Arcing can be due to any number of things, faulty flyback or high voltage transformer. Or humidity. And the list goes on. What can I do to isolate the tube from harm especially while I investigate.

  2. #2


    I'd open it up, dust it off, then start sniffing around (literally!). Look for burned components and bad smells. Oscilloscopes don't usually have flyback transformers, but there could be several HV capacitors that may be blown. Be extremely careful around the HV components.

  3. #3


    It has a 9" Sony crt chassis, I assumed there'd be a flyback. Anyway I had it and my 54120b on last night ... briefly. The culprit exhibited a buzzing crackling sound, not nearly as loud as the last pop I heard. I'd like to remove that chassis and test apart from the scope, so as not to inflict damage to anything else if it goes. Yeah I believe I've had that service manual for a while, but forgot! Thanks.


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