Quantcast

Page 2 of 7 FirstFirst 123456 ... LastLast
Results 16 to 30 of 99

Thread: Technical Explanation for Power Base Converter not working on the 32X?

  1. #16
    Co-Creator of the MegaAmp Raging in the Streets villahed94's Avatar
    Join Date
    Apr 2010
    Location
    Oaxaca, Mexico
    Age
    25
    Posts
    4,541
    Rep Power
    45

    Default

    What about using a 4066+ 74245 setup? The 4066 could switch between the lines based on an input(in this case HI/LOW at B30) and the 74245 would buffer them if need be (bidirectionally)


    Mega Amp: The reference audio circuit for the Sega Genesis/Mega Drive.

  2. #17
    Nameless One
    Join Date
    Apr 2011
    Posts
    77
    Rep Power
    11

    Default

    Quote Originally Posted by villahed94 View Post
    What about using a 4066+ 74245 setup? The 4066 could switch between the lines based on an input(in this case HI/LOW at B30) and the 74245 would buffer them if need be (bidirectionally)
    That could probably work, though I think I have some 74ACT241s around here, which I think should do the job as well (Digikey order history says I ordered some a few years ago, and I always order a few extras :-P ). Just gotta dig through my parts and find it.

    DogP

  3. #18
    The Best Genesis Master of Shinobi GohanX's Avatar
    Join Date
    Oct 2007
    Age
    40
    Posts
    2,159
    Rep Power
    39

    Default

    Quote Originally Posted by Chilly Willy View Post
    Having a mod to allow SMS through the 32X would be a great thing. Don't know how many people would be able to use it, but that's beside the point.
    Having SMS games work from my Everdrive on my Neptune... I think I'm getting some wood here.
    Quote Originally Posted by CMA Death Adder
    Recently I sold the majority of my 32X games for a measly 18 bucks. With it, I bought some tacos. Definitely a more pleasing choice.

  4. #19
    Co-Creator of the MegaAmp Raging in the Streets villahed94's Avatar
    Join Date
    Apr 2010
    Location
    Oaxaca, Mexico
    Age
    25
    Posts
    4,541
    Rep Power
    45

    Default

    Have you tried to patch the wires from the slot(32X) to the edge(to Genesis) and then from the edge take it back to the chip(5805)?


    Mega Amp: The reference audio circuit for the Sega Genesis/Mega Drive.

  5. #20
    Nameless One
    Join Date
    Apr 2011
    Posts
    77
    Rep Power
    11

    Default

    Quote Originally Posted by GohanX View Post
    Having SMS games work from my Everdrive on my Neptune... I think I'm getting some wood here.
    That's awkward.

    Quote Originally Posted by villahed94 View Post
    Have you tried to patch the wires from the slot(32X) to the edge(to Genesis) and then from the edge take it back to the chip(5805)?
    Yeah, that's how it's currently wired. I simply cut the output from the 5805 to the edge, so having those shorted by the PBC wouldn't damage the chip... and then connected the slot to the edge. I never disconnected the inputs from the 5805 since it wouldn't be damaged by being shorted to the PBC. But apparently the 5805 doesn't necessarily simply pass the signals straight through in 32X mode, since connecting the slot to the edge like that doesn't work for 32X games (it does work for SMS and Genesis games though).

    DogP

  6. #21
    Co-Creator of the MegaAmp Raging in the Streets villahed94's Avatar
    Join Date
    Apr 2010
    Location
    Oaxaca, Mexico
    Age
    25
    Posts
    4,541
    Rep Power
    45

    Default

    Quote Originally Posted by DogP View Post
    That's awkward.


    Yeah, that's how it's currently wired. I simply cut the output from the 5805 to the edge, so having those shorted by the PBC wouldn't damage the chip... and then connected the slot to the edge. I never disconnected the inputs from the 5805 since it wouldn't be damaged by being shorted to the PBC. But apparently the 5805 doesn't necessarily simply pass the signals straight through in 32X mode, since connecting the slot to the edge like that doesn't work for 32X games (it does work for SMS and Genesis games though).

    DogP
    Which pins from the 5805 were cut out? Is it going to pins A21-23?


    Mega Amp: The reference audio circuit for the Sega Genesis/Mega Drive.

  7. #22
    Nameless One
    Join Date
    Apr 2011
    Posts
    77
    Rep Power
    11

    Default

    Quote Originally Posted by villahed94 View Post
    Which pins from the 5805 were cut out? Is it going to pins A21-23?
    Yeah, I cut the traces for A21-A23 on the top board, between the white cable and the cart slot.

    DogP

  8. #23
    Co-Creator of the MegaAmp Raging in the Streets villahed94's Avatar
    Join Date
    Apr 2010
    Location
    Oaxaca, Mexico
    Age
    25
    Posts
    4,541
    Rep Power
    45

    Default

    This chip would be ideal: http://www.analog.com/static/importe...ts/ADG333A.pdf

    It would not need even buffering because it has a very low resistance. Something similar would work too.


    Mega Amp: The reference audio circuit for the Sega Genesis/Mega Drive.

  9. #24
    Nameless One
    Join Date
    Apr 2011
    Posts
    77
    Rep Power
    11

    Default

    I finally got around to finding the chip and wiring it up... everything works as expected. Here's a (beautiful M$ Paint) diagram and some pics of how I did the mod.
    32X_pbc.jpg
    The idea is that you need to allow A21-A23 act normally in Genesis and 32X mode, but drive A21-A23 in SMS mode. So this circuit controls the direction using /M3 (pin B30) to pass the 32X signals when high, and pass the PBC signals when low.

    DSC02684.JPG
    Start with a 74ACT241 (pin 1 is at the top of that picture), and bend/solder/cut the legs to jumper the necessary connections.

    DSC02685.JPG
    Solder to A21-A23 (pins B9-B11) on the edge. Use a piece of tape to prevent the solder from flowing down the edge pin (which will wear out the system socket).

    DSC02687.JPG
    Cut the traces to seperate the 32X output from the cart socket (don't mind the solder on the traces... that was from re-connecting it during testing).

    DSC02689.JPG
    Find a place to put the chip (I attached it with double-sided tape under one of the white cables).
    Last edited by DogP; 10-03-2014 at 04:14 AM.

  10. #25
    Nameless One
    Join Date
    Apr 2011
    Posts
    77
    Rep Power
    11

    Default

    DSC02691.JPG
    Solder wires to the 32X A21-A23 output (CN1 pins B11-B13), and +5V/GND (left side of capacitor is +5V, right side is GND).

    DSC02692.JPG

    DSC02693.JPG

    DSC02694.JPG

    DSC02695.JPG
    Route the wires where they won't get in the way of reassembly, solder to the chip according to the diagram, reinstall white cable.
    Last edited by DogP; 10-03-2014 at 04:04 AM.

  11. #26
    Nameless One
    Join Date
    Apr 2011
    Posts
    77
    Rep Power
    11

    Default

    DSC02696.JPG

    DSC02697.JPG

    DSC02698.JPG
    Test.

    Overall, not a very difficult mod... but it does involve a little bit of fine pitch soldering. If anyone gives it a try, be sure to post how it works out. And there probably are other/easier ways to do it, so feel free to experiment a bit.

    DogP

  12. #27
    Road Rasher
    Join Date
    Jul 2012
    Age
    41
    Posts
    423
    Rep Power
    10

    Default

    Wow, just wow.

    Very impressive.

  13. #28
    Mega Driven Raging in the Streets cleeg's Avatar
    Join Date
    Oct 2010
    Location
    Outer Space 2
    Age
    41
    Posts
    3,244
    Rep Power
    66

    Default

    Quote Originally Posted by GohanX View Post
    Having SMS games work from my Everdrive on my Neptune... I think I'm getting some wood here.
    You must spread some Reputation around before giving it to GohanX again.

    Quote Originally Posted by DogP View Post
    DSC02696.JPG

    DSC02697.JPG

    DSC02698.JPG
    Test.

    Overall, not a very difficult mod... but it does involve a little bit of fine pitch soldering. If anyone gives it a try, be sure to post how it works out. And there probably are other/easier ways to do it, so feel free to experiment a bit.

    DogP
    Very cool. I wouldn't dare do this after nearly wrecking my Mega CD last week.

  14. #29
    Co-Creator of the MegaAmp Raging in the Streets villahed94's Avatar
    Join Date
    Apr 2010
    Location
    Oaxaca, Mexico
    Age
    25
    Posts
    4,541
    Rep Power
    45

    Default

    Now the question is: Do all signals needed for a YM2413 pass through unaltered when the system is set to SMS mode?


    Mega Amp: The reference audio circuit for the Sega Genesis/Mega Drive.

  15. #30
    Nameless One
    Join Date
    Apr 2011
    Posts
    77
    Rep Power
    11

    Default

    Quote Originally Posted by madmax2069 View Post
    Wow, just wow.

    Very impressive.
    Thanks.

    Quote Originally Posted by cleeg View Post
    Very cool. I wouldn't dare do this after nearly wrecking my Mega CD last week.
    Nearly doesn't count... go for it!

    Quote Originally Posted by villahed94 View Post
    Now the question is: Do all signals needed for a YM2413 pass through unaltered when the system is set to SMS mode?
    I'm not sure since I don't have one... but from this page: http://etim.net.au/smsfm/smsfm.html , which links to this post: http://www.smspower.org/forums/viewt...?p=58327#58327 , I'd say yes... if you make the circuit to work on the Genesis, it should work through the 32X. The only strange signal is /IORQ, which apparently is on pin B7 (so I guess it's shared with A19)... but it's an output from the system, so it should pass through the 32X just fine. That makes me wonder what other signals are on those upper addresses in SMS mode (why would they skip A20?).

    DogP

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
  •