Tech: Intermittnet transistor?

Archived from groups: rec.games.pinball (More info?)

Hello folks!!

Quick question wpc-s
flipper completely rebuilt and it sticks up sometimes...
6 or 8 flips and up it stays...
turn off the game and down it goes....

I've been to Marvins and I don't question all that info but does it ~really~
happen?

Can a transistor be "sometimes" shorted?

Thanks

Chet
3 answers Last reply
More about tech intermittnet transistor
  1. Archived from groups: rec.games.pinball (More info?)

    Swap the flipper opto board to the other side. Does the problem move?


    C.W.H. wrote:
    > Hello folks!!
    >
    > Quick question wpc-s
    > flipper completely rebuilt and it sticks up sometimes...
    > 6 or 8 flips and up it stays...
    > turn off the game and down it goes....
    >
    > I've been to Marvins and I don't question all that info but does it ~really~
    > happen?
    >
    > Can a transistor be "sometimes" shorted?
    >
    > Thanks
    >
    > Chet
  2. Archived from groups: rec.games.pinball (More info?)

    C.W.H. wrote:
    > Hello folks!!
    >
    > Quick question wpc-s
    > flipper completely rebuilt and it sticks up sometimes...
    > 6 or 8 flips and up it stays...
    > turn off the game and down it goes....
    >
    > I've been to Marvins and I don't question all that info but does it ~really~
    > happen?
    >
    > Can a transistor be "sometimes" shorted?

    I've never seen that type of failure mode in a transistor. I've seen
    transistors fail to an always short, I've seen them fail to an always
    open, and I've seen them fail so that they're neither fully shorted nor
    open (meta-state). But I haven't seen a failure mode of sometimes
    shorted.

    (And I've yanked a LOT of transistors!)

    I'd put my money on a bad opto first. After all, the flipper needs to
    move when there's an _absence_ of light on the receiver; a bad opto (or
    dirty or one with a broken solder joint) can easily cause this kind of
    symptom.

    Swap your flipper opto boards, see if the problem moves with it.
  3. Archived from groups: rec.games.pinball (More info?)

    May times i have had a flipper transistor stick once it is activated.
    Usually it's a predriver transtistor and not the main driver.

    "C.W.H." <84insulation@earthlink.net> wrote in message
    news:wMQwe.13954$pa3.11335@newsread2.news.atl.earthlink.net...
    > Hello folks!!
    >
    > Quick question wpc-s
    > flipper completely rebuilt and it sticks up sometimes...
    > 6 or 8 flips and up it stays...
    > turn off the game and down it goes....
    >
    > I've been to Marvins and I don't question all that info but does it
    > ~really~ happen?
    >
    > Can a transistor be "sometimes" shorted?
    >
    > Thanks
    >
    > Chet
    >
    >
    >
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