Sega, in all their infinite benevolence, decided we didn't really need access lights in our Saturn systems after all, so all systems released after the original oval-button model didn't include one. Simply put, this page shows you how to put the LED back in your newer-model Saturn system.

The concept is really simple. The short version: Add a resistor to R48 and shove an LED where there isn't one. The long version is below. This information comes from a Japanese page which says you should use use a 330ohm resistor, but his own schematic shows a 100ohm. Opening up a Saturn that has the LED will show that a 100ohm is used, so I recommend using a 100ohm. Use a 330 only if you keep burning out LEDs. Tip: If the LED is hot at all then try a 330. At proper operating temperatures an LED generates zero heat.

Here's the controller PCB from a round-button Saturn without the LED installed. You can see Sega thoughtfully left us a place to put the LED. All newer model Saturns have this location clearly marked. The newest ones have no hole cut in the metal shield, but all mid-model units have this hole. If you remove one of the plastic tubes from the power LED of a dead unit you can slot it in for the access LED without trouble.

LED position is clearly marked

Empty hole for plastic piece

Resistor R48 is clearly marked, but may not be easy to find. Shown below is a 1st-model Saturn with the resistor in place. Typically you can find the resistor near the LED in question - look on top of the PCB first, but since you'll have to remove the metal shielding anyway, don't be too surprised when you find yourself flipping it over. Simply attach the resistor and be on your way.

Resistor R48

The original Japanese author has done much of the hard work for you. Please take advantage of it!