Dual Frequency Oscillator (DFO)

Description

The Dual Frequency Oscillator, or DFO as it is more commonly known, is a small device that enables dialing in exact frequencies for replacing the crystal or crystal oscillator of your console. More than that, it also enables two different frequencies to be programmed and switched depending on current use case. The most common application is for proper NTSC/PAL switching. However it has also recently become popular for the consolized NeoGeo MVS market, where the refresh rate is off by just enough to cause issues with modern scalers and displays.

Frequently Asked Questions

What does this do?

• Offers up to 2 frequencies to replace the original crystal or crystal oscillator of your console. These frequencies are usually dialed in to match the original crystals for NTSC and PAL regions.

How do I change the frequency?

• On the DFO board there is a solder pad to wire a switch to. That switch should connect to 5v power and Ground. When the switch is flipped, it will send power or ground to the DFO to toggle between frequencies.
• With some other modifications, like the MODE from TerraOnion, this can be controlled electronically without the need for a physical switch.

What if I only want to convert a PAL system to NTSC or vice versa?

• You can connect the solder pad for the switch directly to 5v or ground. This will “lock” the DFO into a single frequency.

How do I install this?

• Please see our Tutorials section for details. More tutorials will be added as time permits.

If I install this in a MVS does it make the game “faster”?

• Yes. Technically one of the frequencies for the MVS profile increases the speed of the system slightly. This would not be accurate for speedrunning, but it is not generally considered noticeable for casual and even hardcore gaming.

Does this work on all revisions of the systems listed?

• No. The DFO, while versatile, is not guaranteed to work on every revision of a console. Some consoles may be fully incompatible due to their design, Others may be compatible but require a special installation that has not yet been documented.
• Most consoles will work without issue upon installation. Please note that some consoles do not handle refresh rate changes mid-game or while running. This can cause the system to freeze or behave strangely. This is a limitation of the system, not the DFO. In these cases, changing frequencies and performing a reset or switching frequencies while powered off will work best.

Which Sega Saturn’s are known to have the 315-5746 chip? (This is not a comprehensive list. There are possibly more systems with it.)

• VA0-5 NTSC units (all model 1, early model 2s)
• VA9 (many PAL model 2s but not all, all Hi-Saturn model 2, and rarely in some V-Saturn model 2s)
• VA7 PAL (rare PAL model 2 variant)
• VA0-5 PAL