My TV-B-Gone won't work; need debug help.
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My TV-B-Gone won't work; need debug help.

by dwwilson66 on Sun Jun 24, 2012 5:45 pm

I've gotten to the "put in the batteries and test to see if the LED is blinking" step and my LED isn't blinking. My battery pack is testing @ 3.2V. The connection from the battery pack, at the board, is testing @3.2V. The switch tests @ 0V, but reads in the 2.92V-2.96V range, but I only depressed the button about a dozen times. The highest was 3.01V and the lowest was 2.87V.

I've examined my soldering, and everything appears to be good. In the photos, you can see some schmutz at the LED--carmelized PCB from resoldering the battery wires. I cannot see a bridge at the LED or between the LED and battery. And I'm not measuring any continuity between LED leads or LED and power

The o^ in the IC is on the slotted end, and the slotted end faces the LED end. If I recall from troubleshooting, that should indicate that the IC is properly aligned, and the LED not firing isn't a result of a misaligned IC.

So...with battery output good, power input to the board good, the switch apparently working as expected, and the IC properly aligned, I'm guessing it's faulty solder or a bad LED. Does that sound like a reasonable assumption? Is there anything else I should be checking?

Thanks.

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Re: My TV-B-Gone won't work; need debug help.

by adafruit_support_rick on Sun Jun 24, 2012 7:17 pm

You are not reading any voltage on the anode of the LED? That should be tied directly to the battery + terminal.
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Re: My TV-B-Gone won't work; need debug help.

by dwwilson66 on Mon Jun 25, 2012 3:46 pm

Just double checked voltage on the green LED. First, you'll have to forgive me; I can't tell a cathode from an anode once it's soldered in place...and it's tiny enough that I can't really tell or feel which side is flat...but my gut reaction tells me that the (-) side is the flat one on this...which would have it installed properly.

Anyway, when the switch is depressed, I get 3.1V with my black probe on the black wire, and my red probe on the side of the LED closest to the red wire. 0V when the switch is open. I'm having a hard time tracing the circuit after that...I think I go to R5, then IC Pin6..?

After reading the forums about the switch, I'm a little confused...SHOULD it be open and depressing it cause the LED to light? or the other way around?

What shall I look at next?
Thanks
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Re: My TV-B-Gone won't work; need debug help.

by adafruit_support_rick on Mon Jun 25, 2012 4:14 pm

dwwilson66 wrote:Just double checked voltage on the green LED. First, you'll have to forgive me; I can't tell a cathode from an anode once it's soldered in place...and it's tiny enough that I can't really tell or feel which side is flat...but my gut reaction tells me that the (-) side is the flat one on this...which would have it installed properly.


Yes, the flat (cathode) should be on the (-) side.

dwwilson66 wrote:Anyway, when the switch is depressed, I get 3.1V with my black probe on the black wire, and my red probe on the side of the LED closest to the red wire. 0V when the switch is open. I'm having a hard time tracing the circuit after that...I think I go to R5, then IC Pin6..?


That sounds mostly OK. The switch pulls the chip's reset line low when you press it. That should cause the chip's port pin to go low, which will light the LED. Try touching up the solder on the LED leads. If that doesn't work, then I suspect your LED has been transformed into a DED. If you have a spare LED, try replacing it. Otherwise, email support@adafruit.com for a replacement.
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Re: My TV-B-Gone won't work; need debug help.

by dwwilson66 on Mon Jun 25, 2012 4:35 pm

I've got a ton of LEDs...just pop anything in there? they're from various items of varying voltages & I'm still trying to get a handle on what voltage(s) to use on LEDs so they don't become exploDED.
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Re: My TV-B-Gone won't work; need debug help.

by adafruit_support_rick on Mon Jun 25, 2012 5:01 pm

another small green one should be fine
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Re: My TV-B-Gone won't work; need debug help.

by adafruit on Wed Jun 27, 2012 1:05 pm

it looks like you put the oscillator (blue thing) in the wrong spot. check the online tutorial photos please!
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Re: My TV-B-Gone won't work; need debug help.

by jburd01 on Sat Jul 07, 2012 3:07 pm

Blue thing is definetly in wrong place, I just had my 10 year old confirm with his.... He has better eyes than me...
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