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Help with bad soldering - POV4
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Help with bad soldering - POV4

by daveu on Sat Apr 09, 2016 7:59 pm

I think I have melted the board a little.
I placed a resistor, flipped the board, soldered it, went to do the next one and noticed it had slipped and was stuck up in the air, tried to remelt and get it to move and wasn't doing too well. So I cut it off as I was worried about frying the resistor and then melted the legs out of the holes, took a lot of heat to clear the holes of solder.
I now have 7 LEDs working and one not, guessing this is not a coincidence.
I have tested all the resistors and they appear all good, so my guess is I have melted the board and lost the circuit for that one resistor.
My question is, where do I put a jump lead to and from the get the LED to work?
From the USB end of the board it is the 4th LED that doesn't work.

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daveu
 
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Re: Help with bad soldering - POV4

by adafruit_support_bill on Sun Apr 10, 2016 6:53 am

I don't see any obvious signs of damage there. It is tough to tell in the photo, but it is possible you might have a cold solder joint there. This guide has some tips on repairing those: http://learn.adafruit.com/adafruit-guid ... n-problems

The other thing to do is to check end-to-end continuity between pin 6 on the processor chip and the LED.

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Re: Help with bad soldering - POV4

by daveu on Sun Apr 10, 2016 4:31 pm

Thanks for your reply,
I have been doing some re-soldering and testing and have found that it I join the top right (viewed from above the LED) corner (Blue one?) to an adjacent one the light works in all colours but in tandem with the adjacent LED rather than at its own pace (only done this in test mode).
This only works one this corner, other corners do not have the same effect.
Any ideas of what I can do please?

With my skills at soldering....I should have been a welder.

daveu
 
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Re: Help with bad soldering - POV4

by adafruit_support_bill on Mon Apr 11, 2016 8:33 am

Can you indicate on the photo which pin you are referring to?

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Re: Help with bad soldering - POV4

by daveu on Mon Apr 11, 2016 3:19 pm

I've shown the pin on the attached pic.
If I short it to a matching pin on another LED it works fine, just in tandem with that one rather than when it should.
Unlit LED small.jpg
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daveu
 
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Re: Help with bad soldering - POV4

by adafruit_support_bill on Mon Apr 11, 2016 6:25 pm

Check the end-to-end continuity between pin 6 on the processor chip and that pin on the LED. There are exactly 4 solder joints and one resistor between pin 6 and the led. If you can find which part is not conducting, we will know what to fix.

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Re: Help with bad soldering - POV4

by daveu on Mon Apr 11, 2016 8:13 pm

I have now run a wire along the route shown in red on the attached picture, this has fixed my issue.
Thank you for your help
fixed small.jpg
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daveu
 
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Re: Help with bad soldering - POV4

by adafruit_support_bill on Mon Apr 11, 2016 8:26 pm

Great! Glad to hear you got it working.

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Please be positive and constructive with your questions and comments.