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Thread: A2K rev.6.2 mobo black screen

  1. #1
    pietro_tiberi's Avatar
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    Default A2K rev.6.2 mobo black screen

    Hi,

    I'm trying to restore an A2k. CPU and Kickstart are ok (pulled from a working A2K). PSU is Atx and jumper J300 is set properly (pin 2-3 connected). CPU voltage is 4.94 V (pin 14-16).

    But I get BlackScreen...what should i check next?

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  2. #2
    Finger lickin' good Amibayer! matt020's Avatar
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    I have a motherboard with the same issue. It is common for the A2K motherboard to suffer battery damage, and for traces between CPU and Kickstart ROM to be damaged.
    What is the condition of the board around the CPU and ROM chip?
    Amiga 500 / 2000 / 1200 / CD32

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    pietro_tiberi's Avatar
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    Some tracks look like damaged but I tested them with a multimeter an connection is ok. I checked carefully pin 6&7 from CPU to Gary,FatAgnus,buster&co and they are ok.
    I tested pin 2,3,4&5 from CPU to ROM and they are fine....

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    QuarXky's Avatar
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    Hi,
    Pay attention to CPU socket the contact in the red circle not appear so good, be carefull with this.

    Click image for larger version. 

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    Last edited by QuarXky; 10th November 2019 at 22:41.

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    Hello,

    even contacts on ROM socket are green-blue, sign of acid attack! Another thing, with this issue, sometimes, multimeter do not tell the truth! You need to clean all the contacts (solder joints and via) and replace sockets.

    Regards
    Stefano

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    pietro_tiberi's Avatar
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    Connection fron pin1 CPU to Rom is ok. But I have RST pin18 always High. could you helpm me?

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    Hello,

    the right things to do is replace CPU and ROM socket.

    Regards
    Stefano

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