Just some poking around inside a Nintendo Entertainment System! The good old PAL-A Mattel variety sold in Australia. I’ve spent plenty of time with Sega hardware, so I thought it was about time to see what Nintendo had been hiding underneath all that grey plastic. How complicated could it possibly be?

First up, there are six screws holding the outer case together. The plastic is getting rather brittle with age, so a little care is needed. At least the screws are an exciting gold, which makes the job considerably more glamorous than it sounds!

There’s also an expansion port hiding underneath the console, covered by a little plastic panel. Interesting! I haven’t spent nearly as much time exploring the NES hardware as I have with Sega consoles, so finding these little details is half the fun. I wonder what Nintendo had originally intended to connect to that thing?

Once inside, we’re greeted by an impressive collection of metal shielding and that rather unusual cartridge-loading mechanism. Nintendo certainly went to a lot of trouble keeping everything enclosed. The front-loading arrangement is quite different from the straightforward cartridge slots found in most other consoles, although it does look rather interesting from a mechanical point of view.

There are plenty more screws to remove before we can finally get a good look at the motherboard. Some hold the metal shielding, others secure the cartridge mechanism, and there are a few around the external connections. I also found one screw that didn’t appear to have been put back properly, so I suspect somebody might have opened this particular NES before me.

While dismantling everything I even found myself wondering whether I should turn my study into a dedicated repair room. It might be nice to have all this hardware somewhere other than the bedroom, particularly after spending so much time juggling consoles and spare parts. Then again, knowing me, I’d probably fill the new room with even more things to repair!

Eventually we get down to the PAL Mattel CPU-11 motherboard. There’s the CPU, the various RAM chips and the 3197A CIC security chip, along with all the other bits and pieces that make this Nintendo tick. The mainboard layout is quite different from the machines I’ve been spending most of my time repairing.

There’s also a rather large 2200 uF, 25 V capacitor near the power circuitry, with the power and RF hardware taking up its own section of the assembly. The controller-port wiring, power switch, reset button and LED all have their own connections back to the motherboard. It’s a rather tidy little machine once you manage to get past all that metalwork.

Not a bad little exploration, and I didn’t even manage to cut myself this time! Next up we’ll have a closer look at the cartridge connector, because those things can be particularly troublesome after a few decades of use. For now, at least, I’ve got a much better idea of how the Australian Mattel NES is put together.

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