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 Issue with D62
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By: Anonymous: Tim () on Tuesday, May 17 2011 @ 06:42 PM PDT (Read 3584 times)  
Anonymous: Tim

Hi,

I have a problem with the Blue LED 62 turning on both Red LEDs for 9 and 11 o'clock. The D62 itself remains unlit. The unit does not have any other problems and everything was working fine until after adding the final ring. I have inspected all solder joints and they seem to be ok.

I will begin to dissect the schematic tomorrow. In the mean time, does anyone know where I should start with debugging this problem?

Thanks in advance.





       
   
By: Windell (offline) on Wednesday, May 18 2011 @ 04:16 AM PDT  
Windell

I'm going to guess that it's actually the LEDs for 10 and 11, not 9 and 11. Both of those LEDs are connected to line LED6, which also goes to LED 62 on the blue ring.

Check for a possible solder short-circuit at LED 62, and also at the two red LEDs that project to 9 and 11. You may also have one of those two LEDs backwards. Each LED has a flat collar near its base, and they should all be facing the same way.


Windell H. Oskay
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By: Anonymous: Tim () on Wednesday, May 18 2011 @ 06:39 AM PDT  
Anonymous: Tim

Thanks for the reply Windell.

I have checked that all LEDs are oriented properly and that all solder joints do not have shorts. I will try desoldering Blue D62 and the other Red LEDs to see what happens.

As I have said before, all the other LEDs are working fine (even the Red ones when cycled through in test mode), so I find it weird that only D62 is causing problems. Frown





       
   
By: Anonymous: Tim () on Wednesday, May 18 2011 @ 06:57 AM PDT  
Anonymous: Tim

Actually before I desoldered stuff, I checked voltages with my multimeter.

When D62 is supposed to light up, LED6 is 4.66V and LED 2 is 1.58V. The leds that lit up instead of D62 were (from looking at the schematic) D610 and D102, which had forward voltages of ~1.5. The forward voltage across D62 at that time is 2.99.

This seems to be an issue with D62, I will now replace it with a spare.





       
   
By: Anonymous: Tim () on Wednesday, May 18 2011 @ 07:26 AM PDT  
Anonymous: Tim

Ok got it fixed, it was a bad LED. It works perfectly after replacing it.

Now time to work on night-time autodimming code, which I will post later for everybody to use.





       
   
By: Anonymous: PHIT () on Sunday, December 25 2011 @ 01:26 PM PST  
Anonymous: PHIT

Happened to me a lot with leds comes from low quality suppliers.






       
   
By: Windell (offline) on Sunday, December 25 2011 @ 02:02 PM PST  
Windell

These aren't the kinds of LEDs that just come with duds. Almost always, when an LED turns out to not work after soldering, it's because it was overheated during soldering or because the leads were stressed too much during insertion.


Windell H. Oskay
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