Step 7: Testing and Debugging tips
The IR emitters emit very bright light! But the light they emit is invisible to our eyes (IR stands for Infra Red, which means that its frequency is below visible red light). IR remote receivers in TVs can "see" IR, and so can digital cameras.
To test your new high-powered TV-B-Gone you can point it at a TV, push the button on the TV-B-Gone, and keep it pointing at the TV until the TV turns on or off. To test it more thoroughly, push the button on the TV-B-Gone and point it at a digital camera -- if your high-powered TV-B-Gone is working you will see the three blinking lights on the camera: the visible LED, and both IR emitters (even though you will not see the IR emitters blinking with your eye).
If the visible LED didn't blink when you inserted the coin cell into B2, or if both IR emitters do not blink when viewed with a camera (and you can't turn a TV on or off) then you will need to debug the circuit. There are only two areas that can go wrong: the voltage from the new battery packs, or the orientation of the new emitter.
If you have a volt meter, measure the voltage where the wires from the battery holders are soldered to the PCB -- is there 6 volts, with the correct polarity? One of the battery packs I bought at Conrad in Berlin was defective (they are made pretty cheaply), so I had to replace it.
If the voltage is OK, the only other problem could be with the IR emitter -- maybe it is a freaky one with the polarity reversed (one that I bought at Conrad in Berlin had the negative lead longer than the positive lead, unlike any LED I had ever encountered before). If so, then remove the new emitter, reverse it, and test again.