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Question about the Bose 901 Series II EQ light

Discussion in 'General Audio Discussion' started by braincramp, Nov 14, 2017.

  1. braincramp

    braincramp AK Subscriber Subscriber

    Messages:
    304
    Location:
    Freeport, Illinois
    Does anyone know if the light on the EQ should stay solid or pulse ?
     

     

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  2. Blue Shadow

    Blue Shadow I gotta get me a new title

    Messages:
    20,991
    Location:
    SE PA
    The EQ has a neon bulb indicator. Flashing is a sign that the bulb life is nearing an end.
     
    Last edited: Nov 14, 2017
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  3. braincramp

    braincramp AK Subscriber Subscriber

    Messages:
    304
    Location:
    Freeport, Illinois
    The bulb or the EQ?
     
  4. dshoaf

    dshoaf That high voltage buzz Subscriber

    Messages:
    10,156
    Location:
    Santa Cruz, CA
    The bulb only. Not the EQ itself.

    It is like a small version of any neon light you've ever seen. As the neon in the vacuum is deleted, the light wave will start to 'flash' as it alternates on and off. Your eyes perceive it as a flicker.

    Cheers,

    David
     
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  5. braincramp

    braincramp AK Subscriber Subscriber

    Messages:
    304
    Location:
    Freeport, Illinois
    Thank you!
     
  6. Saltydog

    Saltydog New Member

    Messages:
    19
    Hi,
    I'm recapping one of these series II units and thought the neon lamp was gone.
    However, now I find that if line voltage is increased to 120 vac, the lamp will light.
    So, i figured the lamp had a bad solder joint or maybe the resister in series with it had changed spec.
    measuring the resistor gave a reading of 30K, on the money.
    The Voltage coming to the lamp after the resistor was 110 VAC.
    So, figuring the lamp had aged, I could extend it's life a while by dropping the resistence of the 30K resistor.
    I'm finding that no matter how little parallel resistance I introduce, the lamps lighting Voltage seems to remain tied to the line voltage of about 118VAC. (a 2 V drop after I added the parallel resistor.)
    It gets a lot brighter, so more current evidently, but the voltage it receives after I paralleled resistance is much higher now, maybe 115VAC.
    I'm sure a new bulb will probably remedy this phenomenon, but, I'd like to understand whats going on....
    This threads a bit stale, but seems relevant.
    Any ideas?
    Thanks, Robert
     

     

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  7. dshoaf

    dshoaf That high voltage buzz Subscriber

    Messages:
    10,156
    Location:
    Santa Cruz, CA
    Well, let's see, it is about 50 years old now, right? Why not just swap it out for a nice LED-based light that runs on AC?

    That's the direction I'd go.

    Cheers,

    David
     
  8. markn2wae

    markn2wae Mark T N2WAE

    Messages:
    3,020
    Location:
    Scotch Plains, New Jersey
    New neon lamps generally "fire" at about 90 Volts, and then settle down to about 70 Volts and will mantain that Voltage with some increase in current, older lamps may or may not work at these Voltages and may take more to turn them on.

    They exibit negative resistence, that is, once the lamp turns on, it mantains a fixed Voltage with increases or slight decreases in current, sort of like a Voltage regulator tube (0C3 may be one of these).

    If too much current flows the lamp will overheat and go bad or with a LARGE increase, just explode (Don't ask me how I know this!) :)

    Mark T. :music:
     

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