Any idea where to find Atari Lynx II schematic?

There are many sources of schematic for older Lynx 1 but I need Lynx 2 (the smaller model with power LED) The part reference number changed between 1 and 2 so schematic isn't any good. Also Lynx 1 does not have power LED while Lynx 2 has power LED connected to circuitry that makes LED flashes when the battery is starting to get low.

I need it because I need to figure out which resistor is the right one to change. I replaced the original orange LED with white LED, and it's now bright enough to be used as flashlight.

 

There aren't any.

As for your situation, it's because you didn't check the specification of the LED in comparison to the original. You need to put a resistor in series.

Moved to the mods section. You'll have better luck asking these questions about modifications there.

 

Old LED was 1.8v according to my meter, and the new one is 3.0 to 3.2v so shouldn't the new one be dimmer because it's being forced to run at lower voltage? Without schematic I can't tell how Lynx had the power LED wired but I can tell that anode is directly connected to +5v rail and cathode has its own line to the keypad connector, to the mainboard with a few component that makes it steady on with normal power and blink when battery is getting low.

I did find a possible place for schematic: http://www.myatari.com/atarilyn.txt but he has not responded to my email.

 

Not necessarily. They also have a brightness rating. It's highly likely that a 25 year old model is going to be much dimmer than a high bright modern device.

Bruce bought a lot of Atari's stock when they closed, so they'd be the people to ask - although I didn't think they had any Lynx schematics left. You are far better calling them to get a shipping quote.

 

I managed to dig up a schematic of Lynx II


LED goes through 1k resistor and a transistor to ground. Transistor is used to control LED (on, blinking, etc) Using the old formula for resistor:
5v source - 3.2v / 0.02A = 90 ohms for optimal brightness. Reverse calculation (if I didn't screw it up) suggests that with 1k resistor on Lynx, the LED would be getting only about 2mA or 1/10th the typical current yet it's too dang bright. Guess I'll try 2k resistor.