12 vdc Inductive ignition timing light bulb weak flash?

Discussion in 'General Electronics Chat' started by sdowney717, Jul 31, 2015.

  1. sdowney717

    Thread Starter Member

    Jul 18, 2012
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    It flashes fine, but the brightness is gone away. I can not use it to view the mark easily. it used to function well that I recall.
    It is a Sears Craftsman timing light with inductive pickup and 12 vdc power leads.
    Do the bulbs wear out so that they become dimmer?

    I found a link to this site for strobe bulbs
    http://www.goldmine-elec-products.com/products.asp?dept=1208
    So what do you think?
     
  2. debe

    Well-Known Member

    Sep 21, 2010
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    I would check that the inverter is supplying enough voltage, around 250-300v dc. Or faulty capacitor that supplys the voltage.
     
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  3. PackratKing

    Well-Known Member

    Jul 13, 2008
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    An inductive timing light, draws its high energy by clamping onto #1 spark-plug cable... There are 2 varieties of timing light,,, one has a neon bulb [ useless ] the other a Xenon flashtube.
    In a photographic strobe, the flashtube is ionized by the trigger circuit, when the shutter contacts close...

    The trigger circuit dumps its capacitor through the trigger coil, which ionizes the xenon gas, and in turn dumps the main capacitor through the flashtube...

    Xenon timing lights do not have to be as bright as Photoflash, so their firing off the spark-plug high voltage is adequate...
    Over time, if you use it a lot... the flashtube may have lost its xenon, so would not be as bright.
     
  4. sdowney717

    Thread Starter Member

    Jul 18, 2012
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    Thanks.
    Since it has clamps to hook to the battery, and an inductive clamp to go around the spark wire, wont it use the spark wire just as a signal to fire the bulb? Meaning it is not using the spark energy like a neon bulb to flash, this is a xeon bulb. So is it using the 12vdc boosted up to fire the bulb?
     
  5. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    That's how mine works. As per post #3, the xenon tube may have leaked.
     
  6. sdowney717

    Thread Starter Member

    Jul 18, 2012
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    It got very little usage.
    I have had it for 20 years and I used it at most 20 times.
    I suppose I will take it apart and see how it was made.
    I was thinking to time the boat engine easily, but go to use it and it is hard.
    So I will time the engine statically. Engine has a pertronix ignitor.
    So line up the timing marks and rotor to #1 cylinder and twist distributor till it sparks is basically what you do. Or you could put a meter or 12vdc bulb on the distributor to coil wires, positive on 12vdc+, negative on distributor to coil wire.
    Since ignition coil fires with collapsing mag field, when ground turns off after ground turns on, coil fires.
     
    Last edited: Aug 1, 2015
  7. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    I've also had mine about that time and used it even less. Can't even see a spark plug on my present car to see if the strobe still works :D.
     
  8. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    If the car is newer than ~2000 model the timing light wouldn't help any way. All of the timing is done in the ECU. Cam and crank sensors set the timing now.
     
  9. debe

    Well-Known Member

    Sep 21, 2010
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    This is a capacitance pickup one that's at least 30 yrs old & still works fine. The operating principals will be the same. There has to be an inverter to convert the 12V to HV, & a trigger circuit. The dump capacitor on this one stores a bout 650V dc, this is what I would check first. TIMING LIGHT.1.JPG TIMING LIGHT.2.JPG TIMING LIGHT.9.JPG TIMING LIGHT.11.JPG
     
    Last edited: Aug 2, 2015
  10. sdowney717

    Thread Starter Member

    Jul 18, 2012
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    Here is mine, how are you checking the volts?
    Hook up to battery and measure across the yellow capacitor?
    Mine has no numbers on it. What values should it have for capacitance and volts?
     
  11. ian field

    Distinguished Member

    Oct 27, 2012
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    The inverter voltage should be present across the yellow capacitor whenever the xenon isn't triggered.

    The components frequently have no markings - the circuit isn't hard to copy, and those already selling them don't want more people making them.

    The value marked on the photo posted earlier are pretty much typical.
     
  12. sdowney717

    Thread Starter Member

    Jul 18, 2012
    385
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    Thanks, what is 2.0K in mfd??
    I understand the voltage number.

    I connected to a 12v battery charger.When I pull the trigger, voltage across the yellow capacitor is 254volts, which is too low compared to 653 volts?.
    Why would it be low? Is it too low?
     
    Last edited: Aug 7, 2015
  13. sdowney717

    Thread Starter Member

    Jul 18, 2012
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    http://comingsoon.radioshack.com/products/findInStore/2721145?zipcode=23608
    How about this for a replacement?
    I have seen polarized +- on some bulbs, would hooking it backwards destroy it?
    Think my bulb is marked?

    "Because the cathode is more emissive than the anode, the flashtube is polarized, and connecting the lamp to the power source incorrectly will quickly ruin it. "
    So I suppose so!
    https://en.wikipedia.org/wiki/Flashtube

    How can I determine what is + and what is -

    Well, examining the current bulb with a lens shows distinctly different internal end appearance, a collar of metal on one end. So maybe matching the bulb construction will work.
     
    Last edited: Aug 8, 2015
  14. ian field

    Distinguished Member

    Oct 27, 2012
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    2.0K is almost certainly a kind of shorthand. 2uF is a fairly typical sort of value for that application, the K is highly likely to be the tolerance code.
     
  15. bertus

    Administrator

    Apr 5, 2008
    15,645
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    Hello,

    Is the multimeter still in working order?
    I see the battery low indicator in the left corner of the LCD.

    Bertus
     
  16. sdowney717

    Thread Starter Member

    Jul 18, 2012
    385
    13
    I pulled off the little wire plugs that attach to the circuit board and reattached them.
    Flash seems a little better, so next step is test it again on the motor.
     
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