Famicom cartridge 3.3v / 5v voltage check via voltmeter?

Discuss hardware-related topics, such as development cartridges, CopyNES, PowerPak, EPROMs, or whatever.

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work3
Posts: 11
Joined: Mon Jul 01, 2019 2:35 am
Location: Tokyo

Famicom cartridge 3.3v / 5v voltage check via voltmeter?

Post by work3 »

Hi all,

Can anyone be kind enough to tell me where I should use a voltmeter on a famicom or cartridge (legit cart and chinese) to check wether it's using 5V or 3.3V?

Thanks.
lidnariq
Posts: 11432
Joined: Sun Apr 13, 2008 11:12 am

Re: Famicom cartridge 3.3v / 5v voltage check via voltmeter?

Post by lidnariq »

On the console? Just measure the relevant pins (+5V and GND on our pinout)

On the cartridge? All "legit" carts should be 5V. But for the unlicensed things, it's less easy.
  1. If you open the shell, look at the part numbers on the parts. If you see parts that have a "V" in the middle (with numbers on both sides), that's probably a 3V part ... but that's not necessarily a problem. Check for a 3V regulator (it'll look like a "SOT223", or maybe a diode) and for some kind of voltage translation (an array of high-pin-count parts)
  2. If you have an external 5V power supply, provide +5V across the +5V and ground pins, and then measure current from +5V to any random input (such as CPU A0). If you see more than 1-2 milliamps, that's probably a 3V part, with a 3V regulator, without the voltage clamping it should have.
nixjoe
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Joined: Thu Oct 10, 2019 12:56 am

Re: Famicom cartridge 3.3v / 5v voltage check via voltmeter?

Post by nixjoe »

I think all old DIP packages should be 5v. if there's smd package most of them use 3.3v .
lidnariq
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Joined: Sun Apr 13, 2008 11:12 am

Re: Famicom cartridge 3.3v / 5v voltage check via voltmeter?

Post by lidnariq »

DIP and 5V are legacy, which is why they correlate. But for much of the late 90s and early 2000s, 5V SMT was common.

The N64's carts use 3V DIP, but I don't know of any others.
Pokun
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Location: Hokkaido, Japan

Re: Famicom cartridge 3.3v / 5v voltage check via voltmeter?

Post by Pokun »

I guess 3.3 V can be useful if your inventions uses batteries, but sometimes I wish it was easier to find THT versions of parts than it is. SMT isn't very hobby-friendly when soldering, and I heard THT parts are generally lasting longer than SMT parts.
lidnariq
Posts: 11432
Joined: Sun Apr 13, 2008 11:12 am

Re: Famicom cartridge 3.3v / 5v voltage check via voltmeter?

Post by lidnariq »

SMDs aren't kittable at all. There really hasn't been anything like a solderless breadboard.

3.3V isn't just a battery concern, but also any kind of power consumption at all. Computer DRAM and CPUs, in particular, are lower voltage for thermal reasons. Halving the voltage consumes 1/4 the power.

In a finished product, I don't see how through-hole would be more durable than surface mount... and given how it's hard to prototype with SMDs I don't really see how to compare them when prototyping.

That said, modern parts are usually just CMOS, whereas older things were TTL, and TTL is much more tolerant of abuse.
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