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Thread: Galaxian Repair

  1. #1
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    Galaxian Repair

    Another neglected board on the "one day I'll get to it" pile.
    Pretty sad looking original Galaxian. I had a lot of these at one point but I either traded, gave or sold them and just ended up with this one.
    IMAG0184.jpg
    Going over the board all the CPU and sprite rams are missing, a 74ls163 at 5T, missing some of the components for AC to DC, program rom riser missing and C51 missing which is part of the amp circuit and the 18.432mhz crystal was missing.

    First thing is to convert the board to DC.
    Info on the excellent Macro's Arcade site HERE

    Next replaced the missing 74LS163 and put new sockets in at 8B(CPU), 7F(Program) and the graphics roms K1 and H1
    After that program new roms for K1 and H1 and perform the single rom hack.
    Info for that HERE
    Slight amendment to his hack. no need to ground pin 20 just tie it to pin 22
    1) Tie Pin 2 (A12) to chip 7D Pin 5.
    2) Tie Pin 20 (CE) and Pin 22 (OE) to chip 8E pin 13.
    3) Tie Pin 23 (A11) to chip 7D Pin 3.
    4) Tie Pin 26 (A13) to chip 7D Pin 7.

    Time to turn her on and....
    IMAG0187.jpg
    Hmm looks like shes trying to tell me something.....

    IMAG0188.jpg
    Usually a bunch of numbers or letters on the screen like this is a vram fault.
    Sure enough piggy backing a 2114 on top of H3 reveals a program ram error. Bad Ram 1 can mean either the 2114 @ P7 or N7 is bad (or both).
    Not going to muck around so I put sockets in for all the 2114's H3, F3 , P7 and N7
    IMAG0191.jpg IMAG0192.jpg
    Game fired right up and ran all day with no issues! and here I thought it was going to be another Pacman.

    At first there was no sound except a ticking noise that was there regardless of the volume and the amp was getting hot due to the oscillation. Replaced the missing C51 330uf cap and all sound were present and 100%. There is some interference buzzing the higher the volume but that would be due to a bad cap somewhere.

    Lastly the 5 missing 27LS00 sprite rams. I ordered some equivalent 74s201's from Belgium and arrived pretty quick. Damn these things get blistering hot and will need heat sinks.
    IMAG0194.jpg
    I put the 4 in 1 ram replacement board I had made up (see HERE) to good use, works beautifully! I'll need to put a heatsink on the remaining 74s201.
    IMAG0193.jpg
    I think I'm going to order Marcro's 19 in 1 for this board. I really have a soft spot for Galaxian and I think I'll put this in my cocktail.
    I'll continue to keep this board for the next few days and hopefully wont see any issues.
    @Davefjedi you still got that 8 in 1 I did?

    EDIT: Doesn't look like he does the 19 in 1 anymore
    Last edited by Arcade King; 3 Weeks Ago at 05:18 PM.

  2. #2
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    Quote Originally Posted by Arcade King View Post
    @Davefjedi you still got that 8 in 1 I did?
    Sure do Its one of the only PCBs I have kept
    The best action is wrist action!!!!!!

  3. #3
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    I've managed to get in contact with Mike from Macro Arcade and he still sell's the Galaxian 19 in 1 kit.
    If anybody wants to grab a set of pcb's 25 let me know and I'll add it to my order. This is just for the required PCB's, you'll have to source the Eproms, Gals and other components yourself.
    Full assembly instructions, list of required components and binary files to program the Eproms and GAL are on his site.

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