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PostPosted: Sun Dec 03, 2017 1:23 pm 
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A friend gave me a very nice NES frontloader with a few games, 2 controllers, and even a Zapper! Nice!

Sadly, it has the red blink of death, which I thought to be either a dirty cartridge connector, a bad NES10 chip, or both! I decided to pull it apart, clean the connector, and disconnect pin 4 of the CIC/NES10/Lockout chip.

Originally, I'd wanted to desolder the whole chip, neatly bend the pin up, and solder it back in sans pin 4, but my gas-powered soldering iron just couldn't generate enough heat to wick the solder up into the braid.

Next, I tried snipping the pin... but my diagonal cutters were too big. I was able to "nick" the pin, but not cut it.

In my impatience, I used a tiny screwdriver to break the pin at the nick, but sadly the pin pulled out from the IC instead. Not proud of that, I should have waited until I had proper tools. I didn't think it would matter though, as the pin is now disconnected. Besides, I've seen way worse hackjobs on the internet, and the authors of those guides didn't indicate any issues.

When I put the NES back together, I now get no power light. There's a slight "pop" on my TV's audio when I press the power button, but nothing else. Video remains black. Did I ruin my CIC/NES10/Lockout chip? Would a ruined chip keep the console from starting? Should I desolder a NES10 chip from a game (a lame one), and solder it into my console with pin 4 neatly bent away?


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PostPosted: Sun Dec 03, 2017 1:52 pm 
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Location: Seattle
You do not need the CIC IC to be present.

You can add two wires: viewtopic.php?t=10091

You can remove the CIC and 4MHz resonator, move the 1MΩ resistor, and add two wires: viewtopic.php?p=98871#p98871


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PostPosted: Sun Dec 03, 2017 2:23 pm 
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lidnariq wrote:
You can add two wires: viewtopic.php?t=10091


Should I give that a try in it's current state? I can easily add those two wires with the tools that I have.

Any idea why the console appears to be dead?


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PostPosted: Sun Dec 03, 2017 2:34 pm 
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Yeah, try adding the two wires.

The CIC is the device that drives the "power" LED (hence why it blinks when the CIC fails), so if something went wrong with the CIC, it could never release reset and never light the LED.


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PostPosted: Sun Dec 03, 2017 6:14 pm 
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lidnariq wrote:
Yeah, try adding the two wires.

That worked beautifully, thank you very much! I went from a seemingly dead console with no power light to full function by soldering in those two wires. I ended up using the first example (yellow wires) instead of the second (white wires), because my unit was missing a pad from the second screenshot. I'm pretty sure it was on a big ground plane, but I didn't want to be wrong.

After cleaning up the rest of the console and cleaning out the controllers, we've been playing it for a couple of hours with no issues.

I wonder if this would work if pin 4 was not disconnected at all? If so, that would be much safer and easier than trying to disconnect pin 4 from the CIC IC. I can't quite tell from the other thread whether the lockout chip still needs to be there for this to work.


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PostPosted: Sun Dec 03, 2017 6:52 pm 
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Location: Seattle
Yes, the two wires defeat the CIC altogether.

One wire keeps the 4MHz clock from operating and thus keeps the CIC from executing any code; the other wire converts the signal from the reset button to the format needed by the CPU and PPU.

I'm pretty certain that the two wires would still do the right thing even if the CIC IC were missing altogether, but I haven't actually thought about it.

I came up with the "add two wires, remove CIC and clock, move resistor" plan before I was made aware of the "just two wires" mod, and I haven't really thought about it since.


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