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Thread: Amiga 500 Rev 5 with broken power led signal

  1. #1
    Amibayer! riri's Avatar
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    Unhappy Amiga 500 Rev 5 with broken power led signal

    Hi

    Im having a strange problem with this Rev 5 motherboard , no voltage to the power led , i've already checked connector and no luck
    Tried another keyboard and same thing...

    Anyone that had this problem?

    Thanks
    - Amiga A500 Rev 8a1 (not the plus) 1MB + EXT Gotek Drive
    - Amiga CD32 + TF330 + CDTV Keyboard
    - 2x Raspberry Pi 3 with UAE emulator

  2. #2
    LONG LIVE RETROPIE! levo-ace's Avatar
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    The signal for the led comes from u7 pin3 and feeds a transistor to drive the led . just follow the status pin back from the keyboard connector to find the transistor after checking the output of u7.
    Amiga 500 , 500+ , 600 , 1200 , 2000 lots of scsi drives tape streamers cd dvd jazz zip mo.
    too many others brands to list and Raspberry Pi , Arduino.

  3. #3
    Amibayer! riri's Avatar
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    OK , thanks , i will try it
    - Amiga A500 Rev 8a1 (not the plus) 1MB + EXT Gotek Drive
    - Amiga CD32 + TF330 + CDTV Keyboard
    - 2x Raspberry Pi 3 with UAE emulator

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    Amibayer! riri's Avatar
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    Click image for larger version. 

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    Hi , this is the result of the measurements, a little strange, I think...
    Last edited by riri; 15th December 2020 at 21:02.
    - Amiga A500 Rev 8a1 (not the plus) 1MB + EXT Gotek Drive
    - Amiga CD32 + TF330 + CDTV Keyboard
    - 2x Raspberry Pi 3 with UAE emulator

  5. #5
    LONG LIVE RETROPIE! levo-ace's Avatar
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    VERY strange! If you ground the base of the transistor does the led come on? Make sure it is the base so you dont short u7 pin 3 to ground.
    What reading did you get at u7?

    - - - Updated - - -

    Did it work before? is the 500 in working order? is it the original keyboard as some 500 variants drive it high and some drive it low!!
    Click image for larger version. 

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    Last edited by levo-ace; 16th December 2020 at 10:58.
    Amiga 500 , 500+ , 600 , 1200 , 2000 lots of scsi drives tape streamers cd dvd jazz zip mo.
    too many others brands to list and Raspberry Pi , Arduino.

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    Amibayer! riri's Avatar
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    Hi , and thanks for your time

    Suddenly the led came on, but not at all brightness and the drive led lit steadily, as in the photo... without the drive same behavior

    U7 = 7,4v

    This 500 work perfect , its one of the early mobos Rev5. with hitech keyboard.
    I bought it some time ago, but I haven't tested it completely.

    I have reseat all custom chips , no signs of damage , really in good condition mobo.

    Click image for larger version. 

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    Last edited by riri; 16th December 2020 at 21:52.
    - Amiga A500 Rev 8a1 (not the plus) 1MB + EXT Gotek Drive
    - Amiga CD32 + TF330 + CDTV Keyboard
    - 2x Raspberry Pi 3 with UAE emulator

  7. #7
    LONG LIVE RETROPIE! levo-ace's Avatar
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    Where are you getting your ground from for the measurements?
    Amiga 500 , 500+ , 600 , 1200 , 2000 lots of scsi drives tape streamers cd dvd jazz zip mo.
    too many others brands to list and Raspberry Pi , Arduino.

  8. #8
    Amibayer! riri's Avatar
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    From here...

    Click image for larger version. 

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    - Amiga A500 Rev 8a1 (not the plus) 1MB + EXT Gotek Drive
    - Amiga CD32 + TF330 + CDTV Keyboard
    - 2x Raspberry Pi 3 with UAE emulator

  9. #9
    LONG LIVE RETROPIE! levo-ace's Avatar
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    That is a good grounding point. What do you have on the floppy power? (+12 and +5).
    Amiga 500 , 500+ , 600 , 1200 , 2000 lots of scsi drives tape streamers cd dvd jazz zip mo.
    too many others brands to list and Raspberry Pi , Arduino.

  10. #10
    Amibayer! riri's Avatar
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    11,92v and 4,89v
    - Amiga A500 Rev 8a1 (not the plus) 1MB + EXT Gotek Drive
    - Amiga CD32 + TF330 + CDTV Keyboard
    - 2x Raspberry Pi 3 with UAE emulator

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