(Topic ID: 118127)

What happens if you solder a coil backwards?


By mot

4 years ago



Topic Stats

  • 65 posts
  • 38 Pinsiders participating
  • Latest reply 9 days ago by Walamab
  • Topic is favorited by 5 Pinsiders

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    There are 65 posts in this topic. You are on page 2 of 2.
    #51 4 years ago

    To answer your question about heat, when the reverse spike is present, the diode routes it back to its source. The coil will dissipate the spike and heat up ever so slightly, then cool down very quickly. Some heat is also generated in the junction of the diode, because the semiconductor junction presents a voltage drop, 0.7v is typical (why they call it SEMIconductor), so there is some resistance there. But it happens so quickly that the heat doesn't have much opportunity to degrade the component.

    However, because heat vs. time is the life-limiting factor on any semiconductor, it will degrade over time. This is usually the reason your perfectly running machine suddenly smokes a diode or transistor, with no obvious cause. Silicon junction degrades, voltage drop increases, resistance increases, joint heats excessively, melts down, then fails.

    If the diode were a switch contact with close to zero resistance, there would be no heat at its junction, and instead, the coil would absorb the spike completely. And the switch would live forever.

    So, if you're replacing a coil, replace the diode as well.

    #52 4 years ago

    You end up in Hill Valley Circa 1955

    #54 4 years ago
    Quoted from thedefog:

    You end up in Hill Valley Circa 1955

    That's only with flux capacitors.

    #55 4 years ago
    Quoted from beelzeboob:

    That's only with flux capacitors.

    With a flux capacitor wired backwords, you end up in the alternate Biff timeline, only Lea Thompson doesn't have a boob job.

    #56 4 years ago
    Quoted from dendoc:

    of course you can learn from this guy..................
    » YouTube video

    Basically how the supercharger works on Getaway and the ramp on No Fear.

    Edit: Never mind. Hibler already posted this.

    #57 4 years ago
    Quoted from dtown:

    Basically how the supercharger works on Getaway and the ramp on No Fear.
    Edit: Never mind. Hibler already posted this.

    Don't forget about NASCAR and The Shadow, which both propel the ball in a specific direction, as well.

    Any game using a magnet to stop the ball and release is using the same concept. The visible magnet on the playfield is like a stationary plunger rod in the middle of the coil. The coil is wanting to pull the ball toward it, but the stationary rod is preventing it. Games like ToM or TOTAN that catch the ball in a ring (coil) is using the ball as the "plunger rod." Games that throw the ball randomly, like Doc Ock on SM and Sparky on Metallica are using a designed timing of energizing/de-energizing to randomize the direction.

    #58 4 years ago
    Quoted from dendoc:

    of course you can learn from this guy..................
    » YouTube video

    Great video! "You may even call it a green gun. So next time when you shoot someone you may feel a little bit better know that you have done something good for the planet...I guess in more than one way"

    #59 4 years ago
    Quoted from thedefog:

    With a flux capacitor wired backwords, you end up in the alternate Biff timeline, only Lea Thompson doesn't have a boob job.

    which is why you never ever ever want to wire a flux capacitor backwards...

    #60 4 years ago

    This worry (wiring coils backward) can be easily remedied: mark the plastic tab where the lugs are with a Sharpie. Mark each lug 1, 2, 3 (or 1/2) and then just make a few notes before taking things apart (i.e. - BL/Gr - 1, BL/Yel -2). Unless you're bad at writing things down or at reading your own handwriting, this makes it pretty hard to screw up.
    Yes, a better-educated electronics person would go about this differently, but you don't need all the info to do it correctly.

    #61 4 years ago
    Quoted from ccotenj:

    which is why you never ever ever want to wire a flux capacitor backwards...

    Also Huey Lewis no longer does the theme and Don Henley does it instead.
    download (1).jpg

    #62 4 years ago

    The simple answer:

    If you wire a coil with a diode backwards:
    - the diode acts as a short circuit
    - the drive transistor overloads, and melts into a short circuit
    - the fuse blows

    Now, you replace the fuse because it blew and you have coils that are out.
    - the shorted transistor passes enough current to open circuit the diode
    - the coil is now permanently on, overheats, smokes.

    OR
    - the fuse blows again
    - you replace the transistor and the fuse
    - the shorted diode blows the new transistor and the fuse again
    - You repeat until you figure out that the coil diode is bad, or the diode opens

    And yes, the diode is there to absorb the giant "electric shock" that a coil generates when its power is cut (this is how electric shock buzzers work). WPC machines have this diode on the power-driver board. Flipper coils have diodes because they generate a huge spike that we won't want to carry around the machine.

    #63 4 years ago

    To bad besides the op the only ones reading this are the ones that already have a clue but you all did a fine job with explanations I give you all a thumbs up

    Now what if dog was spelled C A T

    4 years later
    #64 38 days ago
    Quoted from dendoc:

    of course you can learn from this guy..................

    Yes, like what not to do. holding both leads when turning the power on. Funniest thing I ever saw. other than someone trying to unscrew the wires from a live wall socket while holding onto the sides of it and getting shocked.

    4 weeks later
    #65 9 days ago

    So, I did this with my new to me No Fear recently (cross-wired the right popper coil) and stupidly added a fly-back diode to the coil (didn't realize there was already one on the board). The only damage I had (other than possibly the diode on the coil) was blown fuses 104 and 110. I replaced these and all seems to be right with the world. I probably just got lucky but I'll take it .

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