Signal Generator Sucking B+??

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by JubileeMan 2555, Aug 27, 2008.

  1. JubileeMan 2555

    JubileeMan 2555 Member

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    Well after what felt like forever, I finally was able to piece together an Oscilloscope, dummy, generator test setup for myself....

    All is working, for the most part, but the Signal generator had some "issues". for the most part, I was able to get it to give out a nice clean square wave. Which is probably all I need at this point.

    ...but.... During tests, I suddenly realized my B+ was down about 50+ volts, and my V1 preamp tube was down from about 200 to almost 85v!

    I tested the generator signal, and sure enough it was registering about -.20 volts?! how odd!

    has anyone experienced this? Is this normal at all? Is there any danger I need to be aware of sticking the generator into my amp?
     
  2. skipm45

    skipm45 Member

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    Is it referenced to AC or DC ? In other words, can the output signal pass through "0v" ?

    Skip
    www.skipzcircuits.com
     
  3. JubileeMan 2555

    JubileeMan 2555 Member

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    I wish I knew the answer to that. I simply don't know enough theory to know what you are talking about...

    ...but I believe I measured everything with the DC setting on my Multimeter.
     
  4. RussB

    RussB low rent hobbyist Silver Supporting Member

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    Your signal generator should be putting out a sine wave, in AC current
     
  5. JubileeMan 2555

    JubileeMan 2555 Member

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    again, I'm not sure if I measured it right. But I do know the amp dropped in voltage.

    I just heard (in PM) from another member that this is all perfectly normal. Also, if I drop the output of the generator, the voltages do go up a bit...

    (BTW, my generator is kinda broken...I don't think the sine wave function works, only the square wave)
     
  6. doctord02

    doctord02 Member

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    I dont understand how your signal generator can have any bearing on your amps B+ voltage... There is no coorelation that I can invision.

    You cant do much of anything without a sine wave signal tho. A square wave is pure clipped fuzz.
     
  7. skipm45

    skipm45 Member

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  8. VikingAmps

    VikingAmps Member

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    An amp thats working as opposed to idling will draw more current and the B+ will go down with incresed current draw. The signal generator is taking the place of you playing your guitar to make the amp work.
     
  9. TimmyP

    TimmyP Member

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    But IIRC it won't usually go down more than 10%, 15% if the supply is really wimpy.
     
  10. Blue Strat

    Blue Strat Member

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    That sounds about right, but there are so many question marks here that it's impossible to say what's going on.

    A square wave output isn't helping. The OP says the generator is broken (WTF? Why use a broken piece of test equipment?). He also says it's "registering -.20 volts with a DC volt meter". None of this is useful information.

    Back to zero. Get a working signal generator and have someone show you how to use it.
     
  11. JubileeMan 2555

    JubileeMan 2555 Member

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    It is going down about 10%. My B+ is around 460.

    I've got one of those AA01 signal generators showing up Monday. I'll see what a perfectly working Generator does.
     

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