ACE2b problem

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Don't Panic. Please wash hands.

    Hi.


    Recently I've got a problems with my Ace2B.


    I want to say at first, that I replaced an NTSC Agnus with a PAL one, so I've lost a guarantee. But I can fix it by myself, only needed the right direction :)


    Looks like (this is my hypothesis) that after several minutes of working something got some heat and stopped working correctly. I made a video, showing my A2000 with a diagrom testing the Chip RAM. Test passed without any errors, but image on the screen starts to deteriorate.


    https://www.youtube.com/watch?v=1tcFNYTGqnM


    When I use a PAL 8375, this situation is happened. When I use an NTSC version computer starts with a green screen.


    Both of Agnuses is fully working - I've checked them on another computer.


    I also tried to remove Ace2B and installed original 8371 - it working perfectly.


    So, I'm good with a soldering iron, what I can do to fix this? Replace 2 multiplexors and/or DRAM at board?


    --


    I want to add, that I've replaced Agnus chip around half year ago. All this time it worked without any problem.

    Please double check if the Vbb capacitor is on the board, and if the PAL Agnus is a VBB type. This may happen because there is one assembled, but the Agnus doesn't need one (then it's actually a miracle if it starts at all), or the other way round: Of you got an ACE2b unit that uses a non-VBB Agnus, and your PAL Agnus is VBB, then it'll act up after a while not having the external cap.


    I can't make out anything from the video.


    I doubt that the DRam or the discrete logic is at fault. Another thing I'd check is proper contact in the two sockets.

    Then contact problems is the only thing I can think of. Remove them, slean with IPA and an old toothbrush. Avoid contact sprays. Use a real PLCC chip puller, do not lever the chip out of the socket, as this will push in the corner pins, causing even more contact problems. Key to not damaging the PLCC84 socket is to lift the chip fully parallel out of the socket.


    Damage by tilting the chip out is not permanent. You can pull the pins back in with a tiny tool that you can make from a needle that you've bent on the tip - this will be able to get unter the end of the contact, and you can pull the contact to the inside of hte socket. Do NOT push from the top, as that will only make it worse.

  • The last reply was more than 365 days ago, this thread is most likely obsolete. It is recommended to create a new thread instead.

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