SNES Red led issue when playing a prototype game.

Hello all,

I wonder if you guys can help me a little bit about a SNES issue.

I have a PAL SNES and I am using a converter (AD-29) to play NTSC games. This setup works with my retail games.

With a prototype I have, when I turn on my SNES, I don't have any picture on my TV and the Red led of my SNES isn't Bright Red, just a bit reddish.

In my opinion, the adaptor isn't the problem as it works with retail games. I think that the problem comes from the proto itself (maybe a short-circuit).

Do you guys have ever seen a such issue with a SNES game ?

Thanks !

 

What's the game, is it using any special chips?

 

The game is Bonkers, by Capcom. And it seems to use classic chips. I will take few pictures for you

 

I think that is almost certainly a hardware problem on the cart - the power LED on the SNES is run off the 5V line using a series resistor - so if it's dim, about the only plausible reason is that something is dragging down the 5V line.

 

Thanks TriMesh, I do agree with you. The cart is full of capcom stickers so it definetly not help to keep it working haha. I need to investigate more, as I want to sell this proto in working condition.

 

I guess all you can do is hope that whatever is faulty isn't the actual EPROMS...

 

Yes, I hope so too. I will try to find a compatible donor card, to test if it comes from the PCB or the EPROMS.

 

Do you have another SNES power adapter to test? A sagging 5v line can be caused by a faulty (or just low quality) power adapter.

I've got a whole box of cheap aftermarket SNES power adapters that won't power a system with a SD2SNES or SuperFX game, but work fine with something simple like Super Mario World...exact same conditions too...dim power light and usually won't boot.

 

This is interesting ! I may try another one (I think I have another power adapter somewhere in my house). Thanks a lot for the advice. I will try this and what TriMesh said this week end

 

Hello guys,

Here is a pict of the Proto.

 

Nothing looks particularly bad or out of the ordinary to me. The cart itself is probably fine. I still think you should try a different console/power supply.

If there really is a short somewhere on the board (that's dragging a known good PSU and the subsequent 5v line down), the EPROMs may still be readable. Pull 'em out and try reading them with a programer (or send it to someone who knows how to do this). You don't need a donor cart to get the data off.

 

Yes, I can remove the eproms to read the data but first, I just want to understand why it doesn't work (as I want to sell the proto, not only the eproms). But I will try the PSU advice.

 

This is probably stupid to ask...but what direction are the chips facing when you put the cartridge in?

 

Chips are facing the front of the unit. As I use a converter, I don't have mechanical problems when powering on the SNES. But thanks for you help. It is not a stupid question

 

Chips face the back, not the front.

 

Damn....I AM DAMN STUPID....

Hit me with a baseball stick....

I haven't change the direction of the cart.

As I am a father since almost a month, lack of sleep don't help in this case. I will try your solution as soon as I get home.

Sometimes, you just feel like as stupid as dog running after his tail....

 

Tristate got it, I just pointed out what his next post would have said.

 

Yes, thanks to both of you.

Don't judge me haha, I feel stupid enought....

 

I hope it hasn't damaged anything - one of the horrible things about the design of the SNES cart slot is that VCC and GND are on the ends of the main connector - so if you plug the cart in backwards you reverse polarize the power lines.

 

Hope so too ! Indeed, this power supply design is quite dangerous ! But we are not supposed to use pcb without plastic cart. Will keep you updated.