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Testing Transistors

Discussion in 'Pinball Tech Support' started by Hammerhead, Feb 10, 2013.

  1. Hammerhead

    Hammerhead Active Member

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    Looking for help on my Road Show - here are the details:

    1) Ted's eyes always look left in test mode regardless of which solenoid you're testing (Player's left, not Ted's left)
    - black lead ground, red lead each outside post
    - Ted's Eyes Left transistor Q52 (TIP 102)
    - tests OK
    - Ted's Eyes Right transistor Q58 (TIP 102)
    - one post reads "740", the other post tests "001"

    2) Lamp Column 8 lights are all very bright and blink bright to not-so-bright instead of on-off
    - red lead ground, black lead to each post
    - transistor Q91 (Tip 36C PNP)
    - one post reads "738", the other post reads "000"

    This means to me I need two new transistors - does anyone else concur?
     
    #1
  2. Menace

    Menace Well-Known Member
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    Yep, that eyes right tip102 is toast for sure. When you replace it make sure you test and replace the associated 1n4004 diode as it could also be shot, and absolutely make sure the eyes right coil is still good and not shorted otherwise you'll blow the new transistor again. (Remember the smoke from the coil is not a good thing)

    As for the tip36c, you sure that's the right transistor for the lamp matrix? Usually the lamps coloumns are driven by tip107 and the lamp rows are controlled by tip102. The tip36c are usually for large coils or other things that require a lot of power. I would verify the transistor type again before proceeding.

    D
     
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  3. Hammerhead

    Hammerhead Active Member

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    Yeah, I noticed after I sent the message that I misread the manual - it is TIP 107 :oops:
     
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  4. Menace

    Menace Well-Known Member
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    Ok, glad that's sorted out on the Tip107. I would say that one is toast as well, but again check all the associated diodes and sockets on the lamps in that coloumn as well when you change it, you might have a short somewhere.

    D
     
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  5. Hammerhead

    Hammerhead Active Member

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    Road Show has a wire ramp along the left side of the cabinet with a series of lamps and switches. The ramp is currently off and the cable with the lamps and switches is hanging loose. The short occured when one of the lamps came in contact with one of the switches. I got a warning message saying there was a short in Row 1 but couldn't find it, and eventually led to blowing F114. Once I found the problem everything appears to work again with the exception of the lamps being ultra-bright. Not sure how the issue went from Row 1 to Column 8.

    Hopefully this is the only resulting problem. Won't know until I have the game back together. Lesson learned.
     
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  6. Menace

    Menace Well-Known Member
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    Keep us posted!

    D
     
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  7. Hammerhead

    Hammerhead Active Member

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    I'm confused. Last night I tried to test the diodes associated with the different transistors on the PCB, and got readings all over the map. Some tested in the 700's, some in the 300's and some in the 20's. Didn't seem to matter how I arranged the leads. They were all the same diode so I expected all the same readings if they were OK. WTF?

    By comparison, checked the diodes along the right wire ramp and they all came out the same, so it doesn't look like anthing's amiss there at least.
     
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  8. flyer666

    flyer666 Member

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    tesdings diodes and transistors are totally difderent....

    Testings diodes is really easy ...One way you get a short and the other way you get flow not matter what the reading is...
     
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  9. Hammerhead

    Hammerhead Active Member

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    Well that makes things a lot simpler
     
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  10. Menace

    Menace Well-Known Member
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    You also have to take into account what else is in circuit when testing diodes, as sometimes you must lift it from the circuit to test correctly.

    When in doubt, take it out! (to test)

    D
     
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  11. Hammerhead

    Hammerhead Active Member

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    SUCCESS! . . . Almost.

    Feeling pretty proud of myself. Changed two transistors with my very limited soldering skills and MAACA/PBRev consultants. Now all head solenoids work and there's no smoke! ;) Now if only I can figure out why Ted's eyes pop out of their sockets when he looks to the left. Likely just an adjustment, but the one eye solenoid seems more powerful than the other one.

    Thanks for any advice or other threads I've read to get this far.
     
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  12. Menace

    Menace Well-Known Member
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    Awesome-sauce!

    If the eyes are popping out, something is worn, missing or mis-adjusted. Check to see if the nyliners are all installed on the eyes. (I think the eyes have them... can't recall for sure. These are the small white bushings)

    D
     
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