Quantcast

Page 1 of 2 12 LastLast
Results 1 to 15 of 29

Thread: 32X Video Combination chip

  1. #1
    Outrunner
    Join Date
    Feb 2010
    Age
    30
    Posts
    538
    Rep Power
    14

    Default 32X Video Combination chip

    My had an extra 32X that I decided to hardware to one of my extra Genesis, since this one didn't have a link cable. Before I did it, it worked perfectly, tested with my link cable for my main 32X.

    When I got done, I tested it all out and nothing happened. So I took it all part and discovered there was a solder whisker between 5+ and Blue. The Genesis video chip blew, no big deal it easy to replace, but so did the 32X Combination Chip.

    The 32X works fine. If you plug it into the genesis and not use the link cable, you get all the stuff from the 32X that you would normally get without a link cable.

    I don't know a whole lot about the 32X. Is this combination chip replaceable or is it some custom Sega chip?

  2. #2
    Outrunner
    Join Date
    Jul 2009
    Location
    Azeitão - PT
    Age
    34
    Posts
    723
    Rep Power
    15

    Default

    It's a SEGA chip, and I havent discovered any direct equivalents to it.
    Anyway, that chip is just 3x 2-to-1 analog multiplexers and a video encoder.

    Are you sure they're blown?

  3. #3
    Outrunner
    Join Date
    Feb 2010
    Age
    30
    Posts
    538
    Rep Power
    14

    Default

    Pretty positive.

    If the 32X is hooked up then you put a 32X game into it. Plug the video cable into Genesis, you get all the stuff like your normally would, except of course, stuff rendered by the 32X. Then if you hook up the link cable, the video from the Genesis doesn't show up, the TV is black with a few scribbles here and there. When the 32X video comes in, it shows up all deformed and scribble like. I assume this is because I blew that combination chip.

  4. #4
    Outrunner
    Join Date
    Jul 2009
    Location
    Azeitão - PT
    Age
    34
    Posts
    723
    Rep Power
    15

    Default

    I suspect theres some other short circuit you have there somewhere near the 32x encoder or the sync signal between MD -> 32x isn't properly connected...

    PICS?

  5. #5
    Outrunner
    Join Date
    Feb 2010
    Age
    30
    Posts
    538
    Rep Power
    14

    Default

    Yeah pictures are good.

    Here is an initial setup. With just the Genesis plugged in.



    Here is with just the 32X plugged in.



    Here are the connections. I tested them again with a multimeter to make sure they were all in the correct position and not shorting. After all, I couldn't see the short between the 5V+ and the Blue until I tested it.

    [Picture of the Genesis one failed to upload multiple times so I gave up]

    Finally the picture of the 32X linked to the genesis. No Genesis video shows up at all, just the 32X video. The Sega logo, "This License" logo doesn't show up etc. If a Genesis game is used, no video shows up.

  6. #6
    Outrunner
    Join Date
    Jul 2009
    Location
    Azeitão - PT
    Age
    34
    Posts
    723
    Rep Power
    15

    Default

    Urgh... really strange. Are you sure you soldered everything in the correct place? Maybe its all reversed?

    See this post: http://www.forums.modretro.com/viewt...d8738ec#p53813
    That pin diagram is reversed :/
    Last edited by Jorge Nuno; 08-22-2010 at 07:41 PM.

  7. #7
    Outrunner
    Join Date
    Feb 2010
    Age
    30
    Posts
    538
    Rep Power
    14

    Default

    I'm pretty sure it is correct, I made the pin diagram myself. I used a piece of wire and a multimeter to map the output.

    I will check it again later to make sure that it is all correct, but I'm pretty sure that all this points to the combination chip being out of whack.

    EDIT: Also the Sync signal or something is making it through, because compare the 32X with the link cable, to the 32X without a link cable. Without the link cable the picture is garbage, but with the link cable the picture is correct, even though it isn't lined up correctly on the TV. (it is actually scrolling)

  8. #8
    Outrunner
    Join Date
    Jul 2009
    Location
    Azeitão - PT
    Age
    34
    Posts
    723
    Rep Power
    15

    Default

    What about on the MD side? for example this pinout here is reversed for the MD socket

  9. #9
    Outrunner
    Join Date
    Feb 2010
    Age
    30
    Posts
    538
    Rep Power
    14

    Default

    Yep, tripled checked. It is all correct.

    Only thing left to do is take a multimeter from the Genesis to the 32X and make sure everything is connected properly. I will get on that and get back to you, but I believe it is all connected properly.

  10. #10
    Hero of Algol kool kitty89's Avatar
    Join Date
    Mar 2009
    Location
    San Jose, CA
    Age
    31
    Posts
    9,725
    Rep Power
    65

    Default

    Quote Originally Posted by Xeniczone View Post
    I'm pretty sure it is correct, I made the pin diagram myself. I used a piece of wire and a multimeter to map the output.

    I will check it again later to make sure that it is all correct, but I'm pretty sure that all this points to the combination chip being out of whack.

    EDIT: Also the Sync signal or something is making it through, because compare the 32X with the link cable, to the 32X without a link cable. Without the link cable the picture is garbage, but with the link cable the picture is correct, even though it isn't lined up correctly on the TV. (it is actually scrolling)
    That makes it sound more like the issue is the sync signal output by the 32x to the TV (or composite video) than any mixing problem. (mixing is synced properly but output to TV isn't -I wonder if a capacitor or resistor in the composite video circuit went bad)
    6 days older than SEGA Genesis
    -------------
    Quote Originally Posted by evilevoix View Post
    Dude it’s the bios that marries the 16 bit and the 8 bit that makes it 24 bit. If SNK released their double speed bios revision SNK would have had the world’s first 48 bit machine, IDK how you keep ignoring this.
    Quote Originally Posted by evilevoix View Post
    the PCE, that system has no extra silicone for music, how many resources are used to make music and it has less sprites than the MD on screen at once but a larger sprite area?

  11. #11
    Outrunner
    Join Date
    Feb 2010
    Age
    30
    Posts
    538
    Rep Power
    14

    Default

    I traced the line from the blue that was crossed with the 5v to a 75ohm resistor, capacitor, then into the SEGA 315-5738.

    The resistor tests fine, and so does the capacitor.

    As you suggested I tested the composite output and it goes through some capacitors and resistors, but they all are fine, and I traced it all the way back to the SEGA 315-5738.

    Just out of curiosity I tested the composite input, again which traces back to the Sega 315-5738.

    Any other suggestions? I also traced the Sync line which doesn't have any resistors or capacitors on it. Though I wonder if it controls a different part of the chip or something. As Jorge Nuno said the chip is 2-1 Analog Multiplexers and a Video Encoder.

    EDIT: I just did a little test by unplugging the following cables
    Sync- does nothing
    Composite- does nothing
    Blue- changes image, less synced.
    Green- same as blue
    Red- same as blue.


    I really do think it's the chip because I traced 3 of those connections and everything in between is just fine. If I got the pinout for the SEGA 315-5738 Do you think we could reverse engineer it and I will make a new chip?

    My guess would be that it would take the RGB from the 32X, and the RGB from the Genesis and combine it into one using the multiplexers, then it would use a video encoder like the Sony CXA1645M to make the composite picture.

    If that was true then maybe the only thing I blew out was the video encoder, but if that was true then how come I still get composite 32X and nothing from the Genesis... Actually I don't even get audio from the Genesis.
    Last edited by Xeniczone; 08-24-2010 at 03:21 PM.

  12. #12
    Outrunner
    Join Date
    Jul 2009
    Location
    Azeitão - PT
    Age
    34
    Posts
    723
    Rep Power
    15

    Default

    Quote Originally Posted by Xeniczone View Post
    I traced the line from the blue that was crossed with the 5v to a 75ohm resistor, capacitor, then into the SEGA 315-5738. That can't be 5V, its GND.

    The resistor tests fine, and so does the capacitor.

    As you suggested I tested the composite output and it goes through some capacitors and resistors, but they all are fine, and I traced it all the way back to the SEGA 315-5738.

    Just out of curiosity I tested the composite input, again which traces back to the Sega 315-5738. This one makes no sense... the 32x doesn't use the MD encoded video for anything...

    Any other suggestions? I also traced the Sync line which doesn't have any resistors or capacitors on it. Though I wonder if it controls a different part of the chip or something. As Jorge Nuno said the chip is 2-1 Analog Multiplexers and a Video Encoder. The Sync signal will lead to pin #23 of the 315-5788


    I really do think it's the chip because I traced 3 of those connections and everything in between is just fine. If I got the pinout for the SEGA 315-5738 Do you think we could reverse engineer it and I will make a new chip? Maybe not just 1 chip, but 2 certainly yes.

    My guess would be that it would take the RGB from the 32X, and the RGB from the Genesis and combine it into one using the multiplexers, then it would use a video encoder like the Sony CXA1645M to make the composite picture. Exactly...

    If that was true then maybe the only thing I blew out was the video encoder, but if that was true then how come I still get composite 32X and nothing from the Genesis... Actually I don't even get audio from the GenesisI still think theres a connection issue here (swapped wires).
    Replied on the quote

  13. #13
    Outrunner
    Join Date
    Feb 2010
    Age
    30
    Posts
    538
    Rep Power
    14

    Default



    It was indeed the 5V+. When I tested it, there was a solder whisker between the purple dot, and the blue dot.

    This one makes no sense... the 32x doesn't use the MD encoded video for anything...
    Yes, but it does use the composite as a pass through, which I'm not getting when I plug a Genny game into it.

    Maybe not just 1 chip, but 2 certainly yes.
    O, of course, simply because I don't have the ability to manufacture dies. Unless you do? :P Yes, you are correct is is the 3788, Mine has blue paint or something on it that covers part of the numbers So I thought it was 38.


    I'm going to check the Genny side, but the 32X I just checked again. No wires are swapped.

  14. #14
    Hero of Algol kool kitty89's Avatar
    Join Date
    Mar 2009
    Location
    San Jose, CA
    Age
    31
    Posts
    9,725
    Rep Power
    65

    Default

    If disconnecting Sync does nothing, I was wrong, the 2 aren't synced properly and that's your problem: either you've got a broken trace somewhere or the sync signal isn't being connected properly from the MD to the 32x. (be sure not to confuse composite sync with composite video)

    If the c-sync signal is somehow dead on the MD side you might try using composite video instead (which had sync, but isn't clean), otherwise you'd have to take sync from elsewhere on the board. (namely the video encoder)
    Otherwise it could be a problem with the sync line you connected on the 32x side.



    Quote Originally Posted by Xeniczone View Post
    Yes, but it does use the composite as a pass through, which I'm not getting when I plug a Genny game into it.
    No, it doesn't; it uses the RGB to pass through and encodes it to composite. (hence potentially improved composite video over the stock genesis)

    On a model 1 genesis, you only need to connect 4 lines: R+G+B+Sync and take stereo audio from the headphone jack.
    6 days older than SEGA Genesis
    -------------
    Quote Originally Posted by evilevoix View Post
    Dude it’s the bios that marries the 16 bit and the 8 bit that makes it 24 bit. If SNK released their double speed bios revision SNK would have had the world’s first 48 bit machine, IDK how you keep ignoring this.
    Quote Originally Posted by evilevoix View Post
    the PCE, that system has no extra silicone for music, how many resources are used to make music and it has less sprites than the MD on screen at once but a larger sprite area?

  15. #15
    Outrunner
    Join Date
    Jul 2009
    Location
    Azeitão - PT
    Age
    34
    Posts
    723
    Rep Power
    15

    Default

    Quote Originally Posted by Xeniczone View Post


    It was indeed the 5V+. When I tested it, there was a solder whisker between the purple dot, and the blue dot.



    Yes, but it does use the composite as a pass through, which I'm not getting when I plug a Genny game into it.

    O, of course, simply because I don't have the ability to manufacture dies. Unless you do? :P Yes, you are correct is is the 3788, Mine has blue paint or something on it that covers part of the numbers So I thought it was 38.


    I'm going to check the Genny side, but the 32X I just checked again. No wires are swapped.

    Solder between the blue dot and the purple dot = short circuit.

    I meant replacing a chip with a little board containing the 2 separate ICs, not a drop-in replacement.

    Please do a continuity test on the 315-5788 pin 23 with the 315-5313 pin 42 and with your sync wire

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •