Snes MultiCart Question (Switch)

[hidden0]

So I Have been Using These PCBs And i wanted to make A MultiCart using one rom and i have successfully made on a 1AON pcb using m27c801 eeprom using this tutorial.

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https://www.youtube.com/watch?v=u3Pk-IQtGrM&list=PL9zkbWjXkdAkHeKH8urcBxy-ViOgZa7zp&index=2

Now I am using mousebitelabs Advance PCB and want to make a Multi Cart with 1 Rom (m27c322)

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https://mousebitelabs.com/2020/07/08/multi-function-snes-reproduction-board-guide/

I made 1 rom File with 2 games using the method and burned it on m27c322 as far as i understood from that tutorial video i Isolated M27c322 Pin (A20) Biggest bus available , Connected to a Switch with VDD and VSS took from PIC12f629 Pin 1 and 8 a nearby Super CIC from the pcb.

The First game works just fine but when i switch it the Super Nintendo Doesn't even turn on.


UPDATE : ISSUE IS RESOLVED
For Games Without SRAM.
If you use 2MB Eprom m27c160 Pull the Pin from the PCB A19 (Biggest Address Bus) and use it with a Switch combined with (VCC or GND)
If you use 4MB Eprom m27c322 Pull the Pin from the PCB A20 (Biggest Address Bus) and use it with Switch combined with ( VCC or GND)
Same Goes with M27c801 Eprom 1MB chip Use the Biggest bus A19.
(make sure nothing is shorting)
My issue was When i was pulling the Pin from PCB it was shorting with the Cartridge slot and i was getting issues.

For Games using SRAM
Will be updating soon.

[Ziggy]

When you say the SNES doesn't turn on... Do you mean you get a blank screen? Or does the power LED not come on? If the later, check for shorts when your switch is in the second position.

I just read through the directions quickly for that PCB, and it's designed to toggle between two EPROMs, not two games on one chip. It uses a 74'74 for this purpose (U10), making the games switch when the console is reset (or you could wire a physical switch to U10 if desired). So if you can't figure it out, then why not try and just use two EPROMs like the PCB is designed to?

[hidden0]

When you say the SNES doesn't turn on... Do you mean you get a blank screen? Or does the power LED not come on? If the later, check for shorts when your switch is in the second position.

I just read through the directions quickly for that PCB, and it's designed to toggle between two EPROMs, not two games on one chip. It uses a 74'74 for this purpose (U10), making the games switch when the console is reset (or you could wire a physical switch to U10 if desired). So if you can't figure it out, then why not try and just use two EPROMs like the PCB is designed to?

Yes i know about the Switching between 2 EEPROMS but i want to make a 4 in 1 Multi Cart , So 2 games in one rom with a Switch and ( Rom switching with included 74hc74)

Nothing is shorted and Yes Console power Doesn't turn ON At all , I checked for shorts May be VSS and VDD is a bit different Then GND and VCC ?

Or may be m27c322 is different then The method i used in m27c801 ?

And i am sure nothing was short with the switch and wires .

[Ziggy]

So you're trying to make a 4-in-1, with 2 games on one EPROM and then another 2 games on a second EPROM? If so, I'm not sure if that'll work.

Remove the 74'74 and see if you can successfully toggle 2 games on 1 EPROM first. If that works, then you know your problem is in the wiring.

The problem with using the 74'74 and a physical switch is that the 74'74 is triggered by resetting the console, but the physical switch you would generally use while the console is powered off. It would get complicated to use them both in tandem.

[hidden0]

So you're trying to make a 4-in-1, with 2 games on one EPROM and then another 2 games on a second EPROM? If so, I'm not sure if that'll work.

Remove the 74'74 and see if you can successfully toggle 2 games on 1 EPROM first. If that works, then you know your problem is in the wiring.

The problem with using the 74'74 and a physical switch is that the 74'74 is triggered by resetting the console, but the physical switch you would generally use while the console is powered off. It would get complicated to use them both in tandem.

74xx74 is not installed yet and cart is set to normal is single rom mode i am just not sure about the m27c322 wiring and a20 thing .
It should work but i dunno why console doesn’t turn on when it is switched to the ground. Vcc game is loading fine with the switch.

[Ziggy]

Try removing the SRAM, and change whatever jumpers (if any) to set it to no SRAM. Remove the 71'139 too, the one at U8. See if it works then.

[Limewater]

Can you post a pic of the underside of your PCB? There is a lot not shown. I don't see the switch at all. Since the switch being in one position is causing your SNES to not boot, it's probably the most important thing to see.

[hidden0]

Try removing the SRAM, and change whatever jumpers (if any) to set it to no SRAM. Remove the 71'139 too, the one at U8. See if it works then.

I tried that it didn’t work same issue happending console isn’t turning on when the switch is on A20+GND when i set the switch to a20+vcc console doesn’t turn on.



Here is the cartridge with the switch setup.

Here is the video of the issue

[hidden0]

Can you post a pic of the underside of your PCB? There is a lot not shown. I don't see the switch at all. Since the switch being in one position is causing your SNES to not boot, it's probably the most important thing to see.

I have taken pictures and a video of the issue to please check the post and see if you can understand anything

I am using pins of 74hc257 for vcc and ground.

[hidden0]

I tried it with m27c160 and another repro board



On this i am using a19 biggest address available when it is tied to vcc the first game works and when it is tied to gnd i m getting black screen.