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Help: Non-working Speakers

Discussion in 'Electronic Basics' started by Darren Harris, Jul 15, 2004.

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  1. Someone asked me to attempt to fix an audio problem with a unique
    video game system that has internal speakers that do not work at all.
    But the system has connections for external speakers. And only one of
    the two external speakers will work depending on what game PCB is
    plugged into the system. http://www.massystems.com/SuperNova.html

    I don't think the problem stems from the game PCBs that hook up to the
    system, and was hoping that someone can tell me how to confirm that
    all involved leads are carrying signals(using a multimeter).

    I need to test the wiring for the internal speakers, as well as any
    external speakers that can be plugged into the system.

    Thanks a lot.

    Darren
     
  2. Does anyone know how to make sure the correct signals are traveling
    through all leads and junctions? All I know is that there is no audio
    for the internal speakers.

    Thanks.

    Darren Harris
    Staten Island, New York.
     
  3. Bob Masta

    Bob Masta Guest

    OK, I'll bite on this one. I don't think you are going to have
    much luck with the multimeter approach, unless you have
    some control over what the signals are. A loud, steady tone
    or buzz might register, but many game effects are too
    transient to see on a meter. A scope is the tool of choice
    for stuff like this, especially because the problem may be
    farther upstream than the speaker leads. It might be a
    bad amp or volume control, in which case the levels will be
    much too low for anything but a scope.

    You mention that one speaker works under some conditions.
    Here's an idea: Get a pair of headphones and put a resistor
    in series with the hot leads, about 1K to 10K range, just so you
    don't blast your ears out. Then check how that sounds on
    the working channel at various points in the chain from the
    amp to the speaker. Compare to the non-working channel.

    My first suspicion in this sort of thing is upstream of the
    speakers, like the power amp or volume control (if any).
    The headphone tester might not be sensitive enough there,
    but worth a shot. Then consider unsoldering and swapping
    inputs to the power amp channels... if the other speaker
    starts working, the problem was upstream of the amp.
    If not, the amp channel is probably bad.

    Hope this helps!




    Bob Masta
    dqatechATdaqartaDOTcom

    D A Q A R T A
    Data AcQuisition And Real-Time Analysis
    www.daqarta.com
     
  4. OK, I'll bite on this one. I don't think you are going to have
    I used my multimeter to check for continuity between the harness edge
    connector that the PCBs plaug into and the system speakers along with
    the external speakers. I'd like to diagram it with ASCII, but wouldn't
    know how to do that here, because it would just show up all garbled.
    But I can send a diagram showing the set-up(and continuity) to anyone
    who wants to see it.

    The system has the red and white outputs for speakers. As well as some
    sort of conversion PCB for playing those arcade games(made to be used
    with arcade monitors) on a PC monitor, and an S-Video output also.
    I would know how to do all that. But four different game PCBs(which
    equate to four different amps) were tried. If the audio of all four
    work when wither oif them are plugged into an acutal arcade cabinet
    should they all work or not work with this particular system?
    I'll ahve to go back there and see what I can find out.

    Thanks a lot.

    Darren Harris
    Staten Island, New York.
     
  5. Okay.

    The problem is definitely not the amps or speaker controls on any of
    the four game PCBs. I tested each of these boards in a full sized
    arcade cabinet, and the audio works perfectly on all of them. The
    external speakers also work perfectly when hooked up to a stereo.

    That means the problem is somewhere in the *harness* of the "MAS
    system", from the PCB connector(where leads for positive and negative
    audio, as well as ground originate) to the (red and white)speaker
    outputs. There is nothing else in the loop. So now I'm wondering if
    the system was wired incorrectly.

    I'm going to try resoldering what is there and perhaps swap some wires
    for new ones, but can anyone point me to a diagram that shows how
    things should be wired between the connector(that attaches to the game
    PCBs) and the speaker outputs, along with how ground is supposed to
    hooked up also? I'm a newbie at this, and really know nothing).

    THanks a lot.

    Darren Harris
    Staten Island, New York.
     
  6. Rich Grise

    Rich Grise Guest

    While you're waiting, you could always trace the actual wires.

    Good Luck!
    Rich
     
  7. While you're waiting, you could always trace the actual wires.

    I have no idea what you mean by that.

    I know where each wire originates and ends, but like I said, I need to
    find out if it is wired correctly.

    Darren Harris
    Staten Island, New York.
     
  8. Don Pearce

    Don Pearce Guest

    Have you compared where each wire originates and ends with where each
    wire *should* originate and end?

    d
    Pearce Consulting
    http://www.pearce.uk.com
     
  9. Have you compared where each wire originates and ends with where each
    There is no way to do that if I don't now where each wire is supposed
    to go. So far no one has been able to tell me.

    1) At one end of the audio harness is the PCB connector. A)Pin-10 =
    positive audio, B)Pin-L = negative audio, and C)Pin-27 = audio ground.

    ***Three wires are supposed to originate at those three pins. But how
    are they supposed to run to the following?

    2) On the other side are the speaker, and also the two outputs for
    external speakers.

    If anyone wants a jpeg diagram that illustrates what I just said,
    please let me know.

    Thanks a lot.

    Darren Harris
    Staten Island, New York.
     
  10. Rich Grise

    Rich Grise Guest

    You know where each wire _is supposed to_ begin and end, but do the
    physical wires actually complete the circuit? By "trace the wires"
    I mean, physically, get down, cut the tie wraps, and visually examine
    the wires themselves. Look for breaks, shorts, anything abnormal.

    A cold solder joint on an edge connector would give you those
    symptoms, and it takes some careful inspection to spot them.

    But from what you've described, the only thing _left_ is the
    actual wires (and their connections.)

    Good Luck!
    Rich
     
  11. I know all that. This is what I've been saying.

    I've inspected all of the wires already, and have a crimp tool, wires,
    and pins for swapping out for new ones. But none of this makes a
    difference if it is not wired correctly to begin with.

    ***I just need someone who knows how speakers are *supposed* to be
    wired to show me so I can determine if this System's audio is wired
    correctly.

    Darren Harris
    Staten Island, New York.
     
  12. I've inspected all of the wires already, and have a crimp tool, wires,
    To better illustrate how the audio portion is wired:

    ***Starting at the PCB connector, there are three leads/pins.

    A) A ground pin(for audio). Goes directly to white external output.
    From this point another wire goes to the positive audio of the
    system's speaker.
    B) A Positive(+) audio pin. Goes directly to the red external output.
    C) A negative(-) audio pin. Goes directly to a soldered area *in
    between* and shared by both the red and the white external outputs.
    From this point another wire goes to the negative audio of the
    system's speaker.

    Can anyone tell me if all this is correct? If it is, I'll have to swap
    out all the wiring and put in new wires the same way.(And/or get a
    different speaker).

    Thanks a lot.

    Darren Harris
    Staten Island, New York.
     
  13. Rich Grise

    Rich Grise Guest

    I can't figure out what you're trying to describe here. What does
    "shared by both the red and the white external outputs" mean, for
    example? What are "A ground, a positive audio, a negative audio"
    pins? Do you have any documentation that tells you which two of
    these are supposed to be connected to the two speaker terminals?

    Do you have any kind of wiring diagram or anything? The
    audio outputs should go to the speakers. What aren't you telling
    us?

    Thanks,
    Rich
     
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