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Thread: MD1 chipmod problem

  1. #1

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    Default MD1 chipmod problem

    Hi, I am doing the cip mod for MD1. The diod was flashing as it should when I pressed the reset button, but the region isn't changing. Also, if I quickly tap the reset, it doesn't reset.
    On the image I have cut off the diod so ignore those wires.

    Since this is a Jap VA1, I had to try and trace the point for the other reset wire myself as the diagrams don't seem to match. But the soldering is good , I traced it from the IC4 chip to the mod chip.

    I am thinking maybe I didn't cut enough of the traces in Jp3 & Jp2? When I try with multimeter it makes a short "beep", then goes silent. But the same happens when I test my unmodded VA4 model? But how deep am I supposed to cut?

    va1.jpg

  2. #2
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    Hmm, i have Japanese mega drive 1 (va3) as well, but I cut jumpers 1 and 4, not 2 and 3 like you did. I'd have to open my console again to check.
    It's not supposed to reset when you tap it quickly. I think the xman game required you to tap reset quickly as part of the game to trigger an event for example.

  3. #3
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    So here is my JPN Model 1 VA4 board. It seems our jumpers are different, with mine have the traces on JP4 and JP1.
    I think you should definite check the continuity for your cut jumpers. It's hard to see but I think JP2 might not be severed (or both).
    region_igr_mod.jpg
    Last edited by blueblue; 01-09-2021 at 04:34 PM.

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    Quote Originally Posted by blueblue View Post
    Hmm, i have Japanese mega drive 1 (va3) as well, but I cut jumpers 1 and 4, not 2 and 3 like you did. I'd have to open my console again to check.
    It's not supposed to reset when you tap it quickly. I think the xman game required you to tap reset quickly as part of the game to trigger an event for example.
    Quote Originally Posted by blueblue View Post
    So here is my JPN Model 1 VA4 board. It seems our jumpers are different, with mine have the traces on JP4 and JP1.
    I think you should definite check the continuity for your cut jumpers. It's hard to see but I think JP2 might not be severed (or both).
    region_igr_mod.jpg
    Thank you (I didn't respond until now because I already refunded the customer and then forgot about it)

    I think you are right about the jumpers, as I now looked at the console again. On the VA1 and possibly VA4 other jumpers should be cut. It is unfortunately that no guides mention this.

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    Attachment 15864
    Please ignore that I connected to jumpers 3 and 2 again. This was only for testing.

    So what we have is: I can't use the reset, but I can hold it down to change colors of the LED. But region doesn't change.
    Compared with previous photo I reconnected the wire to IC2. I think they connect to IC2 but I can't say for sure. I'm using this image:
    http://wolfsoft.de/wordpress/?p=676

    Could I have cut the wrong wire underneath for the reset button? But then reset should work?
    Could I have connected to the wrong reset point (the one next to the number 2)?
    I guess I have to wait for something who have made the same mod.

  6. #6
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    Your attachment didn't work. Can you try reuploading it?

    If your reset is not working, then you most likely didn't connect your reset out correctly.
    Most likely you cut the wrong trace and connected the reset outline from the PIC to the wrong spot.

    If the resolution isn't changing when you change between 50/60hz, then you also have connected the outputs wrong.
    If nothing changes on mode switch, your video switch is probably on the wrong jumper.
    Last edited by blueblue; 02-01-2021 at 09:06 AM.

  7. #7

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    Thank you blueblue
    Attachment 15873
    I tried to upload again.

    I highlight in red what I also tried: to move one cable one step right and to cut another trace. But the trace is already cut underneath and I tested so I know that reset is disconnected.


    If I hold down Reset, the LED changes color. But I can not make it reset the console , and it doesn't do anything other than change color on the LED.

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    Hmm the forums still say the attachment is invalid.

    I get this message when trying to open it: Invalid Attachment specified. If you followed a valid link, please notify the administrator

    I need to open my console again as the LED mount fell off. I'll probably do that over the next couple of days.
    I have a feeling you soldered the reset out to the wrong trace, or you severed the trace at the wrong spot. I will try to make a few clear pictures of that.

    Either that, or you are using the wrong output from the microcontroller. Which firmware are you using? I use borti4938's code, as it sense the reset line if it's active high/low (and works well with the mega cd for me). Maybe your firmware isnt setup for your mega drive reset line type? These are just guesses though. I am sure it's just something simple you are missing.

  9. #9

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    I don't know what I can do to make the attachment work.
    It works now for me in edit mode, I look at it, it looks good.

    Attachment 15888

    My colleague told me I should not cut the wire from the CPU to the via, but I measured and it looks like it is traced from the CPU to the modchip so I must not have cut it proparly.
    He thought the signal doesn't reach reach to CPU for some reason, which is why the reset button can't reset either. But how could that be?

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