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Thread: Sega System 32 Motherboard: No sound

  1. #1
    Bub & Bob's Bubble Buddy
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    Sega System 32 Motherboard: No sound

    So I'm trying to figure out why there is no sound coming from the motherboard. When I do a RAM test, it comes back with IC16 is bad and all the rest are fine. The IC16 is located right by the audio area/Z80, so I thought that could possible be the trouble. However, I replaced it and the problem remains...it still comes up bad as well. I used a known good replacement.






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    Hi

    If the IC reported as bad was replaced and the problem remains, then I would check the traces going to/from that IC and the rest of the sound system. I am not familiar with this board in particular, but that's what I would do.

    Regards.

  3. #3
    Bub & Bob's Bubble Buddy
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    I forgot to mention that the traces looked good too..not even a single suspect one.





    In with the real hardware, out with the bootlegs......who is this I wonder?

    Don't piss off cats or you'll get the Nyanyan Uppercut!

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  6. #6
    Bub & Bob's Bubble Buddy
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    Quote Originally Posted by Xian Xi View Post
    What kind of chip is IC16 exactly? It's likely the Z80 is failing.
    http://www.datasheetarchive.com/dlma...DSA-317071.pdf

    That's the chip. When I turn the audio on, I hear a crackling sound and that's about it.





    In with the real hardware, out with the bootlegs......who is this I wonder?

    Don't piss off cats or you'll get the Nyanyan Uppercut!

  7. #7
    JammaNationX
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    Quote Originally Posted by Fox1 View Post
    http://www.datasheetarchive.com/dlma...DSA-317071.pdf

    That's the chip. When I turn the audio on, I hear a crackling sound and that's about it.
    If it's saying the SRAM is bad and you replaced it and nothing changed then you need to check the control lines on the SRAM.

    20 - CS1 (Chip Select)
    22 - OE (Output Enable)
    27 - WE (Write Enable)

    They are all active low so if any are high then they aren't active but if any are just dead then you have a problem somewhere else. You can then trace to see what they connect to, most likely a TTL chip.

  8. #8
    Bub & Bob's Bubble Buddy
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    Yeah, all 3 of them are active high.





    In with the real hardware, out with the bootlegs......who is this I wonder?

    Don't piss off cats or you'll get the Nyanyan Uppercut!

  9. #9
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    Looks like a DEAD ADDER PCB.

  10. #10
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    It's not adder lol.





    In with the real hardware, out with the bootlegs......who is this I wonder?

    Don't piss off cats or you'll get the Nyanyan Uppercut!

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  12. #12
    Bub & Bob's Bubble Buddy
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    Quote Originally Posted by Xian Xi View Post
    Check what they are connected to.
    20 goes no where, 22 goes to Sega Custom 315-5385, 27 goes to Sega Custom 315-5385 as well
    Last edited by Fox1; 05-12-2014 at 08:06 AM.





    In with the real hardware, out with the bootlegs......who is this I wonder?

    Don't piss off cats or you'll get the Nyanyan Uppercut!

  13. #13
    Mr Neo Fix-it channelmaniac's Avatar
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    Replace the Z80 CPU.
    Call me a cheap bastard... I learned to fix things to save money... even surface mount soldering...

    Visit my website: http://www.arcadecomponents.com

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  14. #14
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    Alrighty, I'll give that a shot. Thanks





    In with the real hardware, out with the bootlegs......who is this I wonder?

    Don't piss off cats or you'll get the Nyanyan Uppercut!

  15. #15
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    Question, even if the reset on the z80 registers as high, could the z80 still be the problem?





    In with the real hardware, out with the bootlegs......who is this I wonder?

    Don't piss off cats or you'll get the Nyanyan Uppercut!

  16. #16
    Mr Neo Fix-it channelmaniac's Avatar
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    Reset will register low for a split second on power up then stay high.
    Call me a cheap bastard... I learned to fix things to save money... even surface mount soldering...

    Visit my website: http://www.arcadecomponents.com

    ---------

    I've repaired boards for many members here.

    Want me to repair your arcade game board? Look here. I do MVS, AES, and many other game boards.

    My repair logs are have moved to NewLifeGames.com!!!

  17. #17
    Bub & Bob's Bubble Buddy
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    Okay, I'll give it a shot tomorrow. Need to go buy a mount for it.





    In with the real hardware, out with the bootlegs......who is this I wonder?

    Don't piss off cats or you'll get the Nyanyan Uppercut!

  18. #18
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    Changed it, no change :/





    In with the real hardware, out with the bootlegs......who is this I wonder?

    Don't piss off cats or you'll get the Nyanyan Uppercut!

  19. #19
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    I have the same problem, socketed the IC16, replaced with a chip that _should_ work (I have same as original chip coming soon). I was suspecting the Z80 too. This is the clock signal for Z80

    17115317528_835f74f599_c.jpg

    The other 8Mhz signals coming from the buffer/driver chip look fine, so either something weird is happening in the Z80 or one of the outputs of that clock driver is done.

    Reset stays high.

    I remember seeing something weird in the address lines, going to scope them now.
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  21. #21
    Raiden's Valet
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    It's low and jumps to high with tiny delay, so reset circuit should be fine. Scoped address lines and all but A0 jumps between low and high.
    Last edited by miisalo; 04-29-2015 at 07:10 AM.
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  22. #22
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    Installed socket and another Z80. Now I can sometimes hear few cracks when powering the board. Same damn problem that fox has...
    Last edited by miisalo; 04-29-2015 at 04:40 PM.
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  23. #23
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    Damn it, Damn it. I fixed this problem before but can't remember what the cause or solution was.


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  24. #24
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    Hopefully you remember in some point. I'm going to scope a bit to see if I find something weird. I do have 32 channel logic analyzer too.

    Edit: that clock signal is shit but works, using another source pin, signal is better but same problem. Also noticed that without Z80, system does not boot at all.
    Last edited by miisalo; 04-30-2015 at 01:10 PM.
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  25. #25
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    I installed exactly same as original sram and while pressing some of the chips I got corrupted sound and IC16 actually passed the test few times. I have now reflowed three custom chips but still no sound and IC16 is bad again.

    The board is quite badly bent so it's probably at least partly issue with solder joints...
    If the freedom of speech is taken away then dumb and silent we may be led, like sheep to the slaughter.

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