Bulbdial Clock – Trouble with Red LEDs

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  • #20219
    kclenden
    Participant

    Just finished building the Bulbdial clock, and everything checked out perfectly until literally the last two LEDs.  Using the “Adjust” mode, all of the blue LEDs work correctly, and all of the green LEDs work correctly.  When checking the red LEDs, however, the last two (the ones at the 4 & 5 o’clock position – which should project 10 & 11 o’clock) do not light.  Instead a combination of blue and red LEDs light.  When the 4 o’clock position red LED should be lit, five red LEDs (at the 11, 12, 3, 7 and 8 o’clock positions) and five blue LEDs (at position 26, 27, 28, 29 & 30 – when starting with the topmost LED as 1 and counting clockwise) are lit.  When the 5 o’clock position red LED should be lit, five red LEDs (at the 1, 2, 6, 9 & 10 o’clock positions) and five blue LEDs (at postions 5, 10, 15, 20 & 25 – when starting with the topmost LED as 1 and counting clockwise) are lit.

    I’ve visually inspected the boards and all of the solder joints look good.  I’ve checked the orientation of the two problem red LEDs, and they appear the same as the 10 red LEDs that work correctly (i.e. flat end faces same way).  Any hints on how I can troubleshoot this?
    #21320
    Windell Oskay
    Keymaster

    Those two LEDs are D610 and D106, which are connected between control lines LED6 and LED10.  The LED10 connection to the red ring is good, because the rest of the red LEDs– all of which are also connected to LED10 –are working, so the problem must either be at the LED6 control line, or is at one or both of those red LEDs.

    When these LEDs cannot light up, the current that would normally go through them needs to go *somewhere,* and so it goes through the other red and blue LEDs connected to lines LED6 and LED10– which are just the ones that you listed on the red and blue rings. 
    Check the soldering first at vertical wire jumper LED6, at the red ring.  This is the most likely place where the trouble could be.  Also check the traces that lead from that point to the two red LEDs that are not lighting.     
    #21321
    kclenden
    Participant

    Thanks.  The problem was at LED6 where it connects to the blue circuit board.  For some reason, the solder was not adhering to the pad on the blue circuit board.  I removed the solder and cleaned the pad and re-soldered.  That solved the problem.

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