Dual Frequency Oscillator

What is this? The Dual Frequency Oscillator (or DFO for short) is a device designed to replace clock/timing oscillators in games consoles. By replacing the standard crystals with the DFO, we can slightly alter/tweak the system timings to our needs. The DFO allows not one but two different frequencies of oscillator to be used, one for PAL and one for NTSC.

This is NOT a plug and play part, fitting requires soldering skills.

Why would you want to replace clock/timing oscillators? The main reason for doing this modification is to fix timing issues on PAL modded consoles when running in NTSC. Our article here explains it in detail, but in short, when you force a PAL console to output in NTSC, it does so using a timing oscillator designed for PAL not NTSC output. Instead of a timing close to 59.94hz (the NTSC standard) you often get one that’s way off spec, perhaps as far out as 59.2hz or more.

Why does timing matter? There are two reason why this matters. First of all, this will cause the image to appear in black and white when using composite video or S-Video connections. Secondly, more modern displays are less tolerant to this variation from spec than the old CRTs used to be. An off spec vertical refresh rate can cause the image to stutter, judder, have vertical lines/streaks across it or prevent it displaying at all.

Where can I get fitting instructions? Currently, fitting instructions are available on this page. This page on German forum cirtuit-board.de also has lots of useful information. You can also try the tutorials section on Mobius Strip’s website.

Please study the fitting instructions carefully and only order if you’re completely confident that you can carry out this mod. We cannot offer refunds for parts damaged due to incorrect installation, nor can we offer technical support for installation of this mod. Please make sure your console is in good working order before installing this mod.

What are the two Saturn versions? Only Sega Saturn consoles with a PLL chip (IC20 on motherboard) with part number 315-5746 can use the DFO.

The “Pin 79 lifted” version requires that pin 79 of the VDP is lifted. If pin 79 is not lifted, do not purchase this version. PAL = 14.2214765100671mhz (Switch connected to Ground)
NTSC = 14.3181818181818mhz (Switch connected to 5v).

The “No Pin Lift” version requires that pin 79 of the VDP is NOT lifted. If pin 79 is lifted, do not purchase this version. NTSC = 14.3181818181818mhz (Switch connected to 5v)
PAL = 17.7344720496894mhz (Switch connected to Ground)

What if I want a different program on my DFO? To reprogram the DFO you require a programmer, we do NOT sell these just yet, but you can get the plans to build one, and find out more about the DFO by clicking here (English) or by clicking here (German).

Will you be stocking the other version of the DFO or the programmer? Maybe, this is still an experimental product.

Will you offer a fitting service? Yes, we hope to in the near future. Contact us if you want do discuss a fitting.