Snes maskrom to m27c322 Adaptor issue

[hidden0]

Hello ,

So i have designed this board based on the this project

Code: Select all

https://oshpark.com/shared_projects/cBdYvYEI

An extend board inspired by mousebitelabs pcb's since i can't order from here and i need alot so i wanted to get them made from china.

Files Attached so i just wrote a game ( which is tested on another board worked fine ) and used
2x 74ALS257 and M27c322 , Wrote Final fighter 3 (Capcom logo is messed up ) and getting only music game is not running properly Then tried another game which is not even loading.

Checking Every Pin of the PCB with multimeter every thing is according to the design and gerber files.
What am i missing here.
Can provide Easyeda link as well if someone want to take a look would be great help.

[hidden0]

Is there anything else using this adaptor with lowrom or hirom boards ?

Update : used the same extender board with 1a0n and it worked fine.

now trying on anyother Hirom Board for Earthbound , 1J3m.

UPDATE : did not work with Earthbound as well , Gave me garbage on screen

I am using 74ALS257m
But the pcb suggested 74HC257

can that be an issue ?

[Limewater]

UPDATE : did not work with Earthbound as well , Gave me garbage on screen

I am using 74ALS257m
But the pcb suggested 74HC257

can that be an issue ?

It is possible that is the issue.

The ALS and HC parts are the same in terms of logical output, but there are significant differences in terms of electrical characteristics. There is a non-trivial chance that it just won't work as a drop-in replacement for the HC.

[hidden0]

UPDATE : did not work with Earthbound as well , Gave me garbage on screen

I am using 74ALS257m
But the pcb suggested 74HC257

can that be an issue ?

It is possible that is the issue.

The ALS and HC parts are the same in terms of logical output, but there are significant differences in terms of electrical characteristics. There is a non-trivial chance that it just won't work as a drop-in replacement for the HC.

The board i am using is pin to pin from oshpark

https://oshpark.com/shared_projects/cBdYvYEI

I don't understand why it worked with 1a0n board with 4MB rom.

and not worked in any other board like 1J3m and 1J0n the same board i desoldered which worked in 1a0n.

Is there any other source for pinout from Snes maskrom to m27c322 i can find.





What am i doing wrong ?

[Limewater]

When talking about these things, more detail is better. I do not understand what you are saying here.

Are you saying that you have successfully gotten Earthbound to boot on a 1a0n? Or are you saying that you successfully used one of your 74ALS257ms on a 1a0n?

I am guessing the first is correct, since I don't think the 1a0n takes a 7400 series chip.

I am just saying that, assuming you copied the oshpark pcb correctly and everything else is correct, the 74ALS257m is a real possible problem. It may notbe , but it is relatively easy to check. You generally shouldn't use an LS part as a drop-in replacement for an HC part.

[Limewater]

Seeing you just posted images, honestly your solder job looks a little rough. I would clean that flux off of the bottom of the board and check for shorts. It probably looks a lot better in person, but I can't tell anything from my end except that it does not look like something I would trust.

[hidden0]

Seeing you just posted images, honestly your solder job looks a little rough. I would clean that flux off of the bottom of the board and check for shorts. It probably looks a lot better in person, but I can't tell anything from my end except that it does not look like something I would trust.

Soldering is not the issue i can assure you that its a no clean flux and i m very good at soldering and i have checked all the points .

To be clear
The adaptor with the same 74LS chips worked with. Lowrom pcb with Spiderman 4MB rom.

But it did not work with 1j0n (final fight 3) 1j3m (earthbound)

I have tried 2/3 times but it just didn't work.

But when it worked fine with spiderman lowrom 1a0n pcb makes me believes design and pcb must be okay and problem is somewhere else so i desoldered the same adaptor and connected it with 1j0n again with final fight 3 rom ( eprom is fine cuz i checked it on repro pcb from mousebitelabs) it just goes to the intro screen and give me garbage screen logo .

Hope i explained it well.

[marurun]

Random question: are those two pins on the front-most chip in the lower right supposed to be bridged? I assume so, because that would be hard to miss noticing…

[Ziggy]

Random question: are those two pins on the front-most chip in the lower right supposed to be bridged? I assume so, because that would be hard to miss noticing…

That chip is the original mask ROM that comes on the board. Instead of pulling it off completely, it looks like he just lifted pin 31 and bridged it to pin 32. Pin 31 is /OE (output enabled) so I'm guessing tying this pin high or low (in this case, +5v or ground) will enable/disable the mask ROM. Pin 32 is +5v, so he jumped the /OE pin to it.

[hidden0]

Random question: are those two pins on the front-most chip in the lower right supposed to be bridged? I assume so, because that would be hard to miss noticing…

That chip is the original mask ROM that comes on the board. Instead of pulling it off completely, it looks like he just lifted pin 31 and bridged it to pin 32. Pin 31 is /OE (output enabled) so I'm guessing tying this pin high or low (in this case, +5v or ground) will enable/disable the mask ROM. Pin 32 is +5v, so he jumped the /OE pin to it.

That's correct

I am gonna try to Manual verify and check pins from the work of this guy

https://mousebitelabs.com/2020/01/28/27 ... ter-board/

And see if my Maskrom to m27c322 adapter is exactly as it is suppose to be.

SOLVED :
So turned out the there is a missing trace in the design i got from Oshpark , That is seriously Strange.

I checked from mousebitelabs.com all the traces and found out there is no Ground trace from Snes maskrom to the adaptor board :/

Stupid mistake took so much time and effort. Not every thing is internet is gonna work

Thanks anyway guys.

The link i shared above is a GOLD resource for Snes repros.