Help with Starfox problems

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Fisher
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Help with Starfox problems

Post by Fisher »

Hi.
I just got an Starfox cartridge, board only (SHVC-1C0N5S-01).
It's locking at the first screen, sometimes the word Nintendo appears completelly, sometimes part of it and sometimes I just get a black screen with the music.
I tried to remove the resistor? that is plugged in place of the HC04, through pins 1 and 2 and put a wire in there.
So far so good, the game worked, but freezes after some time.
AFAIK, this componnent feeds the clock signal to the Mario-1 chip.
Is it so critical that without it the game crashes or I have something else wrong?
Is it really a resistor or some kind of inductor? The measured resistense is about 1ohm.
Thanks in advance.
qwertymodo
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Re: Help with Starfox problems

Post by qwertymodo »

It's an inductor, not a resistor, and yes, it's necessary. Without it, I'm guessing you're getting a lot of noise on the clock, which could definitely crash the game.
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Fisher
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Re: Help with Starfox problems

Post by Fisher »

The pictures I saw show the inductor with small trimmed terminals.
Mine is almost touching the 256k SRAM.
Could this be the source of my problem, since I'm dealing with high frequency RF here?
qwertymodo
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Re: Help with Starfox problems

Post by qwertymodo »

Could be. Photos would help.
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Fisher
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Re: Help with Starfox problems

Post by Fisher »

I took 2 pics with my crappy phone, hope this helps to have an idea.
20161230_212628.jpg
20161230_212645.jpg
The capacitor on the left was missing.
If I have read the pictur I saw fine, it's a 22mf x 6,3v.
I don think it's critical, is it?
Can an external clock generator be used?
qwertymodo
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Re: Help with Starfox problems

Post by qwertymodo »

Almost looks like pad #2 from the U6 footprint is ripped off the substrate, but I don't know if that's even connected to anything. I'll have to take a look at my board once I'm home from vacation after the first.
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Fisher
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Re: Help with Starfox problems

Post by Fisher »

I tested with the multimeter and got continuity there.
Maybe My soldering iron was too hot when I put it back.
It seems to go to pin 69 of the Mario chip.

Edit: I figured out! It's a faulty inductor!
If I have undestand what I read, the original inductor is 0,1 or 0,2 microhenry (I just can't know if the second belt is brown or red), but I have put a 27 microhenry one.
Even far bigger, it seems to be working fine.

Thanks and happy new year!
Kismet
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Re: Help with Starfox problems

Post by Kismet »

Fisher wrote:I tested with the multimeter and got continuity there.
Maybe My soldering iron was too hot when I put it back.
It seems to go to pin 69 of the Mario chip.

Edit: I figured out! It's a faulty inductor!
If I have undestand what I read, the original inductor is 0,1 or 0,2 microhenry (I just can't know if the second belt is brown or red), but I have put a 27 microhenry one.
Even far bigger, it seems to be working fine.

Thanks and happy new year!
It's definitely red. Gold-Red-Gold on mine at least. That said I need to point out something, you said you have a bare PCB (no plastic cart case?) Well the StarFox game has a metal object in the cartridge that connects to that pad behind 59 and 60 on the PCB. This is an extra ground AFAIK that would normally make contact with the metal cartridge slot. Someone who was cleaning cartridges stated that the cartridge slot ground and the RF shielding in the SNES completes a ground circuit. YMMV.
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Fisher
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Re: Help with Starfox problems

Post by Fisher »

Interesting!
I didn't know that.
Is it all shielded, just like the N64 cartridges?
Could you please show some pictures?
So I can try to make something similar.
Thanks in advance.
Kismet
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Re: Help with Starfox problems

Post by Kismet »

Mario-Chip1-SFX.jpg
I scaled this down from my iPhone and quickly drew an arrow to where it makes contact on the PCB

Incidentally the Super Mario RPG cart also has one in the same place. So it might exist on all expansion-chip carts. That could also explain why these carts are more finicky since there might be a weird ground loop. If someone creates a new cartridge plastic they might not realize this.
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SMRPG-vs-STARFOX-Ground.jpg
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Fisher
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Re: Help with Starfox problems

Post by Fisher »

Thanks!
It's working fine now, but I think I should try to implement this shielding to avoid future problems.
It would be easier if I found someone selling a StarFox's shell only. :mrgreen:
I would buy it complete, if it wasn't costing a kidney!!

By the way, I just put a clockgen I found floating around... 28.570Mhz, a slight overclock!
Some people say the game becomes smoother, but I saw no difference besides a faster moving ship and the intro sound not playing to the end.
Maybe it's me, but I think it's better as it was designed to be.
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