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  1. (*steve*)

    CCFL lamp tester

    And CCFL's are driven by AC, so no need to distinguish one end from the other.
  2. (*steve*)

    Plotter Cutter Help

    Well I'm wondering if the power supply is actually getting that voltage or if it's due to leakage. If they fall dramatically under a very light load it points to something different to what it might be if they are comparatively stiff.
  3. (*steve*)

    Repairing a motherboard

    That's probably a 2SK3638.
  4. (*steve*)

    Plotter Cutter Help

    What's coming out is very high frequency AC. If you're getting any output, the must be something coming out of the transformer. And be reeeeeeealy careful measuring stuff with the power on. It's no exaggeration to say it can kill you. Try putting a resistor (say 1k) across the output that's...
  5. (*steve*)

    Power Dissipation Across A Transistor In Cutoff

    If you look at the datasheet you'll note that voltages are typically measured with reference to the emitter. In that respect, you are not applying a voltage to the emitter. There are good technical readings for this, one of which is that the base emitter junction is forward biased, so you need...
  6. (*steve*)

    Power Dissipation Across A Transistor In Cutoff

    So, apply that to a transistor.
  7. (*steve*)

    Plotter Cutter Help

    Yeah, 300VDC on the mosfet and AC to the transformer is correct.
  8. (*steve*)

    Repairing a motherboard

    Keep your fingers crossed. :-) The mosfet should be the same or similar. Can you read the part number on it?
  9. (*steve*)

    Power Dissipation Across A Transistor In Cutoff

    Not at all. Do you understand transistors at all? What is the voltage across a switch when the switch is open?
  10. (*steve*)

    Repairing a motherboard

    Yep, there's only 4 turns, should be easy. A short somewhere, it could be the mosfet, or the mosfet could have been a subsequent failure.
  11. (*steve*)

    Plotter Cutter Help

    Hmmm, try lifting one end and doing that again.
  12. (*steve*)

    Wanted: Jvc gf 500

    I want to know what a jvc gf 500 is.
  13. (*steve*)

    Repairing a motherboard

    You would be best off rewinding that inductor with the same gauge of wire, assuming that the core is intact.
  14. (*steve*)

    Power Dissipation Across A Transistor In Cutoff

    The Vce is the voltage across it. This will depend on how it is biased. If it is in cutoff, what do you think the voltage across it will be?
  15. (*steve*)

    Plotter Cutter Help

    When powered on, is the power supply silent, or is it making a ticking sound? Measure the resistance across the large diode (both ways) just above and left of the centre of the board. It's the black cylinder with the silver stripe near one end.
  16. (*steve*)

    Ic=C x dv/dt

    But first you need to get your equation correct, and probably in terms of radians per second.
  17. (*steve*)

    Building a circuit on a bread board

    Yeah, but there are three power sources in that circuit and certain interpretations of... ...will yield bad results.
  18. (*steve*)

    Light therapy device

    Cool. Presumably he has good reasons backing up what he says.
  19. (*steve*)

    Building a circuit on a bread board

    Did you look at the circuit?
  20. (*steve*)

    Building a circuit on a bread board

    I can't quite follow your question, but I can follow the circuit. The ground symbols are common, but only two power supplies have a direct connection to it. Beware of having outputs of your power supply grounded. I presume the outputs are floating.
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