Any clue how I'd find a p/n for this?

Virtua fan

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I'm trying to troubshoot the gun sense boards on my Confidential Mission. These boards use 2 infrared LEDs per assembly, and 3 of the 10 boards have issues where either 1 or 2 of the LEDs is not working (see the close up photo, the LED on the right is obviously burned out rather than just a bad solder joint).

The part number for the full assembly is 838-13145-02. These boards run for about $30 apiece new, and I was hoping I could source replacement LEDs from Mouser or similiar as they're probably just a few pennies/each.

Does anyone have any clue how I'd go about identifying the LEDs or finding a replacement?

Any help would be greatly appreciated, as it'd save me like $80-90 in parts. Thanks!
 

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I've never had to actually repair IR beacons, but here's what I'd do.

If you have a scope or logic probe, check the LED itself for pulsing. I could see a game flashing the LEDs at a certain frequency to make it easier for the gun to tell the beacons apart from miscellaneous IR sources. If you find pulsing (and I'm talking +V->0->+V->0, not a little filter hum), you will NEED a scope to get the forward voltage drop, and you can't really continue without it.

Now, measure the forward voltage drop across the diode (voltage, anode to catchode. If pulsing, go with the voltage at high, not the average). Do this with a board that has two good LEDs, even if it means doing a little soldering work. (They're probably using a single resistor for two LEDs, and if one is blown open, it'll throw your measurements off.) There, you have one spec.

Now for the harder ones. Go out and get a variety of IR LEDs with the same FVD, but with various brightnesses and wavelengths. Get identical pairs of each kind (this is important later). The physical size and shape don't matter as long as they'll fit in the game. Pull the good LED and make a test rig that'll power the LED at the right voltage. Use a CCD camera (almost any digital camera will work, even cellphone cams) in a dark room to compare their brightnesses and colors. Make sure they're pointing exactly the same direction -- LEDs have an uneven light distribution. Set aside the ones that look the closest in brightness at the same voltage.

Now you have to guess-and-check your chosen few. It might take any of a variety of wavelengths, or it may be pretty picky. Replace both diodes with identical candidate LEDs so you know for sure it's not just picking up the factory diode. Stick it in the game and see if you have tracking problems in that corner.
 
I checked the manual, but it doesn't go into details on the board. I'd suggest pulling one off and looking at it under a magnifying glass for some type of number on it...
 
Or, look at the photo transistor or whatever is receiving the light to see what it's part # is as the data sheets for it will tell you the wavelenghts of light it will be sensitive to. This will help you find the right LED.

Also, check the data sheets for the LED to see how much current is allowed to flow through it. You may need to adjust the value of the resistor a bit to keep the current flow low enough to keep them from frying as it sounds like they are running too hot.

RJ
 
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