Test Failed. What's Wrong?

by Joanne on Mon Oct 24, 2011 5:10 pm

I recently purchased a TV-B-Gone kit version 1.2.
A component had not been included in the kit but it was quickly sent it to me.
My husband is a former IBM engineer and well acquainted with breadboarding and soldering.
He assembled the kit according to instructions and got to the first test.
He inserted the batteries. The green led did not come on.
Again, according to instructions, he checked the polarity of the led and made sure that the microcontroller was inserted properly. The dot was difficult to see but it was there.
The batteries were fresh.
According to his diagnosis, the microcontroller is either not programmed correctly or defective.
What now?
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Re: Test Failed. What's Wrong?

by adafruit_support_bill on Tue Oct 25, 2011 5:02 am

If you post photos of the front & back of the board we can double-check your assembly.

Also, if you have a meter, measure the voltage between ground & the '+' leg of the LED.
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Re: Test Failed. What's Wrong?

by Joanne on Thu Oct 27, 2011 12:50 pm

Ok, my husband measured the voltage between ground and the positive side of the green LED. It measures slightly more than 2 volts. (2v).

I've taken pictures of the board. How do I post photos?
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Re: Test Failed. What's Wrong?

by adafruit_support_bill on Thu Oct 27, 2011 1:08 pm

Hmm. Looking at the schematic, the positive side of the LED should be at VCC. What do you measure across the battery terminals?

You can post photos using the "Upload attachment" tab below the edit window.
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Re: Test Failed. What's Wrong?

by Joanne on Thu Oct 27, 2011 3:12 pm

Here are the photos.
Attachments
DSC02179.JPG
DSC02179.JPG (660.02 KiB) Viewed 2011 times
DSC02177.JPG
DSC02177.JPG (726.45 KiB) Viewed 2011 times
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Re: Test Failed. What's Wrong?

by adafruit_support_bill on Thu Oct 27, 2011 3:55 pm

On the back side, there are some problems with the soldering. You need to solder all 8 legs of the microprocessor socket. You have 4 with little or no solder and 2 that could use more. Also, some of your solder joints have a 'frosty' appearance indicating that the solder didn't flow properly (a 'cold joint'). Use a clean hot iron and re-flow any joints that are not smooth and shiny. If you are using a low-powered iron (<25 watts) you should pause a bit between joints to let it heat up again.

On the front side, your microcontroller is in backwards. Powering it up this way may have damaged the processor, but fix up the soldering and turn the microcontroller around and test it again. If you can't get it going, we do have replacement microcontrollers in the store.

Excellent photos by the way :D I wish they were all that well lit and focused!
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Re: Test Failed. What's Wrong?

by Joanne on Fri Nov 11, 2011 10:31 am

Well, my husband says to order another microcontroller, so I will do that.

He said to please be sure the dot that helps orient the microcontroller is visible, because it was a pinprick before and he could barely see it.

I would like to ask you--how can you tell it is upside down from this photo? If I know that, I'm sure we can get it right this time!

I guess we should have assembled it as a team effort. My husband is the electronics guy--but I have better eyes!

Thanks for your help.
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Re: Test Failed. What's Wrong?

by Joanne on Fri Nov 11, 2011 10:38 am

I could be missing the obvious here. Is the dot my husbands talks about that indentation in the lower left corner? If so, can I assume it goes in the upper right corner?
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Re: Test Failed. What's Wrong?

by adafruit on Fri Nov 11, 2011 6:32 pm

Joanne wrote:I could be missing the obvious here. Is the dot my husbands talks about that indentation in the lower left corner? If so, can I assume it goes in the upper right corner?


thats right!
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