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PostPosted: Sat Oct 28, 2017 5:59 am 
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Joined: Sat Jul 04, 2015 9:58 am
Posts: 568
Location: -29.794229 -55.795374
Got some news, not that good, but soo...

I almost think the problem was solved!
I got an old 60 to 72 pin adapter board and the game ran more stable.
It didn't crashed anymore, but it resets a lot.
Here is a picture of the guy:
Attachment:
File comment: New old adapter
20171028_101940.jpg
20171028_101940.jpg [ 457.22 KiB | Viewed 73 times ]

The only diference I noticed from this adapter to my other is the existence of this circuit:
Code:
   
      __________ 
      | C945P? |     22X (?)
      |________|  +---||----+
       |  |  |    |   10K   |
       |  |  +----+--/\/\/--+---> PPU A13
      GND |      1K
          +----/\/\/---> VCC
          |
          = 1mf x 35V
          |         
    NES cart Pin 35 

I think it's a CIC stun circuit, pretty common on old pirates back in the day.
I've put an X on the capacitor's last digit is because it's erased, also, the transistor's identification is not very clear.
I read what I could. :oops:
The capacitor (22X) is disconnected from the resistor on the transistor's side. If I connect it the game resets when I navigate through the pause menu.
I also tried to add a resistor that seemed to cure the reset issue on the adapter, but the only thing I got different was corrupted graphics.

I also tried to take off some pullup resistors on the console's motherboard, but the only one that I could see a diference was the in the CPU's /IRQ pin.
Without it, the game didn't boot at all. So, I've put it back.

Just in case someone is curious on how it crashes on clashman's stage, I've made a video of it.
Hope someday I can finally solve this issue.
Thanks in advance!


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PostPosted: Sun Nov 19, 2017 1:42 pm 
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Joined: Sat Jul 04, 2015 9:58 am
Posts: 568
Location: -29.794229 -55.795374
Well, I'm not surprised at all...
As I related in this post, I made a Crisis Force repro.
Unsurpringly, the game just crashes in this clone. :cry:
It seems to be random. Any clues on how to debug it?
Maybe measuting the tensions on the WRAM chip can give some clues??

The only differences I can see between this clone, the other clone that works and an NES/FC schematics is that the clock generation is made with 2 transistors, instead of 2 not gates.
Could this be the cause of the whole mess??

For now I have 3 games that crashes, any suggestion of some more I could try to see what happens?
Curiously the pirate Gradius 2 I have works just fine.


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