Hi I've come across something I've never seen before. It's a Mario Bros/Duck Hunt game with a bright yellow cartridge. It has the normal label that says Nintendo entertainment system on the bottom. The back side has nothing on it accept for the Nintendo pat. pending made in japan branded on the cartridge. It the Nintendo seal of quality and looks completely real. I put it in my Nintendo and it plays like a normal game. Any idea what it's worth.

Pics would help a lot. It sort of sounds like a test cartridge but I am not an expert in that field.

certainly sounds like a test cart. Pics would be able to confirm that with some of the more experienced members.

So freakin' cool. Pics of board?

I have no way to open the cartridge. I need to get a tool for it.

amazing find!

Its a test cartridge, very rare and worth a lot. Gloryhole!

Wait, does this even exist?

I must have this. No idea on price unfortunately.

Interesting that is for sure.

How is it a test catridge if its a duck hunt game really cool though

Awesome find! Are you going to sell or trade this?

I've never known a lot about test-carts, but that looks like test-cart cart.
Not sure how/why a SMB/DK label got on a yellow cart like that... to my knowledge (which again, is limited when it comes to test carts), it shouldn't exist. The only two explanations I can think of:

a) somebody swapped a test cart with a SMB/DK label, which only an idiot would do
b) it's some sort of pirate cart from Asia or something.

Please sell it to ihavethatpma, I hear he pays well in Nigerian ding-dongs.

Paging Limbofunk! I was unaware of a SMB test cart. Zelda test cart, yes. Interesting find..

Talk to Otto of Penguin, they are the resident experts on Test carts.
Or maybe talk to Qixmaster, I hear he is in the market for one lately too

Yes, PM Limbofunk (Otto) or Penguin to find out more info.  I've seen a Duck Hunt test cart but not a SMB/DH one.  Definitely cool and worth a decent bit to the right collector.  Great find!

Cool look..... But it was never made. A duck hunt was made, but not a Mario/duck hunt. A real oddity.

In for more info, interesting.

Sure looks like a legit test cart. Couldn't service centers order parts individually? Does it still count if a service center put together their own test cart?

Looks great. And people said SMB/DH carts were cheap!

Most likely it was just assembled at a Service Center using a replacement label and shell. There's no record in any of the binders I have for this cartridge. These parts were available to any service center and they could have easily made a yellow test cart of almost any game. Very cool find thou, def one of a kind!

Nice find!

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This. ^^^^