(Topic ID: 251146)

Lamp matrix issue WPC 89

By monkfe

4 years ago



Topic Stats

  • 6 posts
  • 2 Pinsiders participating
  • Latest reply 4 years ago by monkfe
  • Topic is favorited by 1 Pinsider

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    U10  pin 13 driver board TAF (resized).png
    #1 4 years ago

    So I'm having an issue with three rows out on my taf (using a seigecraft lamp test board here so the issue is on the board)...Checking the Tip 102's three are not lighting up on my logic probe. So when I go back to the 74LS74 I'm checking the outputs at the ones that are working to confirm against the three that are not right...I get to U10 pin 13, I get nothing. (although this is not control the transistor that's giving me a problem) Schematic shows pin 13 connected to pin 1 via board trace. I check all my other 74's and they're all connected (ohm/continuity check) and giving an output. So I had replaced these with sockets and now I'm thinking I screwed up the trace somehow and now I remove the socket again only to find that pin 13 goes nowhere...just simply a single trace on the board both sides? Anyone have any idea how this is? The lm339 in this circuit is an overvoltage cut off correct? How do I determine if its shutting off the 74LS74?

    #2 4 years ago

    With power off try reseating the short/wide ribbon cable on both ends that connects at the MPU and at the driver board. Sometimes when you have multiple things out like 3 rows of lamps, you may just be missing a signal coming from the MPU.

    #3 4 years ago
    Quoted from monkfe:

    I remove the socket again only to find that pin 13 goes nowhere.

    On the driver board, U10 pin 13 is also tied to U10 pin 1, U11 pin 1 and U11 pin 13.
    U10  pin 13 driver board TAF (resized).pngU10 pin 13 driver board TAF (resized).png

    #4 4 years ago
    Quoted from PinballManiac40:

    With power off try reseating the short/wide ribbon cable on both ends that connects at the MPU and at the driver board. Sometimes when you have multiple things out like 3 rows of lamps, you may just be missing a signal coming from the MPU.

    I'll give it a look in the morning....

    #5 4 years ago

    Hoping for a good result.

    #6 4 years ago

    Yes that was the issue...two end pins on the mpu were just slightly bent, I'm guessing they weren't making contact...all is well now....Thanks gents...

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