LED issues

[oklared]

I’ve just completed putting the red ring together and have hit a snag.  I put the clock in alignment mode and worked my way up to test the red layer. I started aligning the bulbs and when I reached the LED at 3 o’clock it will not light and a cluster of 5 LEDs on the bottom blue ring come on instead.  This blue cluster is located at either side of the three o’clock position.  The blue ring in alignment mode works fine.  Polarity of the red LED is correct and I’ve looked for everything else that is obvious. The chronodot has not yet been installed.  Help!

[Windell Oskay]

The LED that at 3:00 (not the shadow, but the LED) is D102 on the schematic– it does signal lines LED2 to LED10. The other LEDs that are lighting there are on LED2 as well. It is likely that the LED there is either shorted or damaged– I’d suggest replacing it with a spare.

[oklared]

I have a DC power supply at my office so this morning I momentarily applied voltage to the LED in question and it lit fine.  I then applied voltage to some of the other red ones just to double check polarity and no issues with that.  So it is back to square one.

[Windell Oskay]

This was never a polarity issue. One of three things is going on here:

1) You have a short circuit somewhere, accidentally connecting two of the LED lines

2) You have an open circuit– missing a connection between the LED lines and the (right) LEDs

3) A damaged LED. It may still light, but may have very different voltage characteristics than its neighbors, which would cause the effect that you see.

If you would like to test with the power supply, apply the 5 V (with a resistor) to lines LED10 and LED2.  If you would like to test to see what happens if you remove the red LED without actually desoldering it, you can clip one of its two leads between the circuit board and the LED body, and separate it just a small amount so that it doesn’t touch. Then, touch a new red LED across that point to see the effect of putting a new LED in that location. The LED lead that you cut can be repaired by bending it so that the two cut ends touch, and putting a tiny dot of solder between them.

And, if all else fails, you can send the clock — in its current state — back to us for us to take a look at it. If you would like to do that, please use our contact for to request an RMA.

[oklared]

I think I’ll go the RMA route.  I know enough to be dangerous and I don’t want to really screw something up.
Thank you for the suggestions.

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