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Thread: Alvin G. & Co - Al's Garage Band goes on a World Tour

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    Alvin G. & Co - Al's Garage Band goes on a World Tour

    Started having a proper look at AGBGOAWT today. The first major issue seems to be power supply related - resets of the machine and the sound board dropping out so the music stops. Managed to record both earlier today: https://clips.twitch.tv/OilyPopularJayNomNom

    First stop the wiring diagram to see what's common between the sound board and the MPU:
    cabinetwiring.jpg
    So the MPU uses 20vdc and 5vdc, the sound board uses 12vdc and 5vdc. Let's have a look at the 5vdc side of things.

    On the PSU, I get 5.2v at PP2 on the orange/blue to black. On the MPU, that drops to 4.9v and occasionally 4.8v. When it's at 4.8v, right flipper or the auto plunge will cause a reset. Similar levels to the MPU on the sound board.

    So looking at the schematic:
    powersuply.jpg

    I checked the input to the 5v circuit and it's a shade over 9vac. There's a pot (VR2) to adjust the output of the 5v circuit. Turns out clockwise decreases the output voltage, anti-clockwise increases it. Dialed it up to 5.4v when unloaded and the game no longer resets.

    Played for a little while this evening and I'm still occasionally having issues with the sound dropping out, but the MPU is not resetting so that's good. The regulator is quite hot though, like burn my fingers hot, so I guess I really need to do some replacements on the PSU.

    Things still to look at:
    • Garbled DMD for some modes, animations
    • Sound drop outs
    • PSU maintenance
    • Hum that can be fixed by tapping the cabinet - something is loose
    • Left bump button doesn't seem to fire
    • Right bump button clashes with autoplunge coil
    • Flippers need rebuilding
    • Insert GI Isn't working.

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    Alvin G formally Gottlieb, check all your grounds...Double up on them as a form of fault finding rather than disturbing what is there. If the problems go you know where to start looking.

    Pretty sure the 5 volt reg is the cheaper adjustable type used on Alvin Gs so it might be worthy of swapping but a bad earth with cause a reg to get hot as well which is worthy of noting.

    The reg should never get that hot. They do have thermal protection to shutdown if they run to hot and this will kill the 5volt till the heat drops off before resetting itself.

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    Quote Originally Posted by Autosteve View Post
    Pretty sure the 5 volt reg is the cheaper adjustable type used on Alvin Gs so it might be worthy of swapping but a bad earth with cause a reg to get hot as well which is worthy of noting.
    Bad earth or bad ground?

    That reminds me, another for the list:
    • Garbled DMD for some modes, animations
    • Sound drop outs
    • PSU maintenance
    • Hum that can be fixed by tapping the cabinet - something is loose
    • Left bump button doesn't seem to fire
    • Right bump button clashes with autoplunge coil
    • Flippers need rebuilding
    • Insert GI Isn't working.
    • Replace line cord


    The line cord has a 3 pin molex in it. Any thoughts on replacing like for like or removing it? I guess the pro is that it will disconnect if someone trips over the cord, but the con is that it adds another point of resistance and potential failure?

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    Ground to each of the boards I meant. A hum that is fixed by hitting the cab certainly points that way too.

    Line cord change it. Wires will rip out of the Molex if you trip on the cord it and far to much chance the frayed ends of the mains line will short out before the line fuse.

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    Quote Originally Posted by Autosteve View Post
    Ground to each of the boards I meant. A hum that is fixed by hitting the cab certainly points that way too.
    Half only have 2 screws holding them for a start. :-/

    There definitely something off in the ground wiring - the menu and exit/service credit button intermittently stop responding. Pressing on the connectors on the PSU seems to fix that.

    Quote Originally Posted by Autosteve View Post
    Line cord change it. Wires will rip out of the Molex if you trip on the cord it and far to much chance the frayed ends of the mains line will short out before the line fuse.
    Cool. I figured the molex to make it more convenient to assemble at the factory and less useful to me. An IEC socket would've been a better option, but would've cost more too. New line cord on the list, and I'll bring it all the way through to the filter.

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    I'll fix this connector too. Without using these to stop the wires shorting: https://www.bunnings.com.au/ramset-7...of-25_p2260646IMG_20180517_143509.jpeg

    I wonder if that's why the insert gi doesn't work.

    Sent from my TA-1012 using Aussie Arcade mobile app
    Live on Twitch, Tuesdays 6pm + other random times | twitch.tv/ajfclark | You can vote for what machine I play, click here, follow my channel and type '!vote' in chat for details | Movember: mobro.co/ajfclark

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    This chip on the DMD driver board looks a bit odd too...
    IMG_20180517_144136.jpeg

    Sent from my TA-1012 using Aussie Arcade mobile app
    Last edited by ajfclark; 23rd May 2018 at 12:17 PM.
    Live on Twitch, Tuesdays 6pm + other random times | twitch.tv/ajfclark | You can vote for what machine I play, click here, follow my channel and type '!vote' in chat for details | Movember: mobro.co/ajfclark

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    Few more shots on the PSU. And the original position of the 5v pot.IMG_20180517_150958.jpegIMG_20180517_143518.jpeg

    Sent from my TA-1012 using Aussie Arcade mobile app
    Live on Twitch, Tuesdays 6pm + other random times | twitch.tv/ajfclark | You can vote for what machine I play, click here, follow my channel and type '!vote' in chat for details | Movember: mobro.co/ajfclark

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    Exciting - following this. I got offered a garage band four years ago and regret not trying it out. What an awesome and weird machine
    The name's Max; Bond Max

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    Quote Originally Posted by maxi View Post
    Exciting - following this. I got offered a garage band four years ago and regret not trying it out. What an awesome and weird machine
    The music is great, and somewhat surprisingly the stereo is actually noticeable.
    Live on Twitch, Tuesdays 6pm + other random times | twitch.tv/ajfclark | You can vote for what machine I play, click here, follow my channel and type '!vote' in chat for details | Movember: mobro.co/ajfclark

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