You're absolutely right that the "smooth" look you see on Nintendo/Sanyo monitors (like the 20-EZV and 20-Z2AW) isn't purely a product of the monitor itself, even though those monitors are high quality. The key difference really
does come from how Nintendo's boardsets generate and condition their RGB video signals.
Let's unpack the main contributing factors:
Nintendo's arcade boards — especially from
Donkey Kong through
Punch-Out!! and
Super Punch-Out!! — include
analog low-pass filtering on each of the RGB outputs before they ever reach the monitor.
- This was done with simple resistor-capacitor (RC) networks designed to gently roll off the very highest frequency video content (fine details, sharp pixel edges).
- The result: softer edges and slightly blended pixels, which makes scanlines and mask segmentation far less pronounced.
- Most other manufacturers (Capcom, Sega, Konami, etc.) drove their RGB signals "hot" and unfiltered to maximize apparent sharpness. That gives a crisper but also grainier and more "segmenty" look.
It's essentially a difference in
bandwidth: Nintendo's RGB signals typically have a -3 dB point around 5 MHz, whereas others often extend well past 7–8 MHz. That's enough to make a visible difference.
Nintendo tended to design their color encoder stages with slightly lower drive voltage (less than 1 Vpp per channel), and with a gamma curve that was a little more "video" than "computer."
This gentler color transition makes bright-to-dark edges less abrupt, which adds to that "smooth" appearance.
The Sanyo 20-EZV and 20-Z2AW both have onboard
video inverters and clamping circuits, since Nintendo boards output
inverted video (0 V = white, 5 V = black).
- That inversion circuit adds another small RC network and buffer transistor stage, which further smooths out the signal.
- So even if you bypass the Nintendo PCB and feed in a normal RGB source (non-inverted, through the inverter disabled), you lose that extra filtering. When you run a standard game board into the Sanyo's normal (non-inverted) input, it doesn't pass through those filtering stages.
Nintendo's boards are
not exactly standard 15.734 kHz / 60.00 Hz NTSC-timed. They often run slightly lower — around 15.6–15.7 kHz — and with a bit more active line time.
This subtle timing difference slightly stretches the horizontal scan per pixel, leading to:
- Marginally less space between horizontal scanlines
- A softer raster overall
It's tiny, but combined with the low-pass filtering, it contributes to that "painted" look.
Sanyo used extremely high-quality CRT tubes with
fine-pitch shadow masks and well-tuned beam focus, often slightly de-focused intentionally at the factory for Nintendo's spec.
This was part of their attempt to make Donkey Kong's graphics look more like a "home TV" image than a razor-sharp vector-style computer monitor. The slight defocus plus the lower bandwidth signal creates a natural anti-aliasing effect.
The "smooth look" of Nintendo/Sanyo monitors isn't because they're interlaced or fundamentally unique in design — it's a
chain effect caused by:
- Low-pass filtering of the RGB signal on Nintendo PCBs
- Extra smoothing in the Sanyo's video inversion and clamp circuits
- Slightly different horizontal timing and beam focus tuning
When you connect a sharp, unfiltered game board like
Street Fighter II, you're feeding in a much higher-bandwidth signal, and all the smoothness disappears — proving the Sanyo itself isn't doing magic.
If you ever want to test this empirically, you can reproduce Nintendo's "look" on another monitor by inserting a simple low-pass filter — say, a
100 Ω resistor in series and a 100 pF cap to ground on each RGB line — right before the input. That should produce the same subtle blur and reduction in visible scanline segmentation.
