Checking Your IR Remote and Replacing Your IR LED in the RoboquadPosted by GWJax on Thursday, 17 January 2008
Wait! Don't throw your batteries away in your remote until you do this check! If this check doesn't work, the problem may be your IR LED.
If you didn't see that in your digital camera, then it just might be the IR LED, a transistor, or the CPU. Follow these simple tests, and we'll go from there.
First, we are working on the Roboquad Remote.
Step 1 - Make sure you have tried new batteries and that the batteries are seated well - then retry the steps in the video. If it is still not working, then proceed to Step 2.
Step 2 - Open the remote. Then, remove the batteries to access the 2 hidden screws. You will be removing 6 of them - 2 are on the top, 2 are in the battery compartment, and 2 are on the bottom.
Once this is done, then it's time to crack it open. You might have to pry it open, as some glue might have spread on the case. Don't worry: you won't break it as long as the screws are out. When you open it up, it should look like this:
Now, let's check the LED to see if we are getting anything to it. In the photo below, you will see 3 pad in a sideways triangle, and it's located to the left of the blue component: "a 4Mhz crystal." The one you want is the one on the far left, which is in front of Q1's collector. Find the Black battery line and make note of where it is connected to the battery housing. Now, get out your meter and put the setting to 20v DC (or auto DC) depending on what kind of meter you have. Place the batteries inside the housing; make sure to remember where the black wire was connected. Place your black ground lead from your meter in between the battery and spring. Place the red lead from the meter on the test pad in front; For the Q1's collector, you should read almost 0V. Now, press a button, and the stop button and it should read about 0.35v or so - and then back to 0V. If this test works, then Q1 is working and the CPU is working. The IR LED is dead and should be replaced.
If that did not work, then what could be the problem? It could be a bad transistor or CPU - let's find out. First, we are going to test the CPU. Find the pad that says TEST; it is under the CPU and has a black dot on it. Still with the ground in place, put your meter on the bottom test pad. You should get a 3.?? and 4.??, which will flip back and forth. Go ahead and press a button. It will now read 0V and stay that way for about 1 second. Then, it will return to its normal state changing voltage. If this did not work, then you may have a bad 4.0mHz crystal or a bad CPU chip.
Next, we should test the crystal. Place your red lead on the left leg for the blue crystal; you should get around 1.23V. On the right leg, you should get from 0.1? to 0.2? volts. If this doesn't check out, your crystal needs replacing. Now, check the other pads of the triangle - the top pad should read 4.5v, and the bottom pad should also read 4.5v. It will have those readings until you press the stop button - if you do so, it should drop to around 4.4v and then back up. if you don't get these readings, then the transistor is bad and needs replacing. If everything here is a-ok, then the IR LED is bad and will need replacing.
To remove the PCB board, remove the batteries and you will again have to remove 6 screws: 2 on top, 2 in the middle, and 2 on the bottom. Remove the board from the housing, and you will then have to remove the LED. I use a solder sucker iron from Radio Shack; you may use solder braid if you choose.
Make sure that when you reinstall the new LED, that you put it in correctly: the flat spot of the LED is to the left for the remote. The picture is on the PCB in case you forget. Screw the remote PCB back in, and do the first check again. If you don't see the LED blink, then you may have a bad solder joint. Make sure that you solder the LED from the top side. If you see it, reassemble the remote in reverse order.
I hope that you enjoyed this article and please keep coming back to see what else is new. Also, you can feel free to leave me a message or a comment, and I'll try to help out as much as I can.
Until then, GWJax