MeggyJR – power-on display problem

[mikpar]

Just finished assembling the MeggyJR RGB.  Powered on the first time, and I seem to have a problem.  I am not certain exactly what to expect, but one complete column of the LED display does not light up.  Column 5 (counting from the left) remains dark through out the display sequence.  I have examined the back of the circuit board, and do not see any obvious soldering problems.  All the pins of the LED matrix appear to be well seated in their sockets.  I suspect a bad solder joint, or a blown component.  But I am no electronics whiz.  can anyone give me a clue as to what to check next?

Also, is there a description somewhere of what the initial power on display should look like?  There maybe other useful symptoms in the light sequence but I really don’t know what to expect.  If this forum supports attachments, I can upload a short video showing the sequence on the LED display if that would be at all helpful. 

Thanks

[Windell Oskay]

Okay, column #5 – the column directly under LED D4, is really “Row 4” in the matrix, starting with row 1 on the top (your right hand side) and working down. Row 4 is at pin 23 of the LED matrix socket, and is controlled by transistor Q3, through resistor RB3, from pin 11 of the microcontroller. 

So, check those points for a possible missing solder joint.  See also a previous forum post on the topic:  http://www2.evilmadscientist.com/forum/viewtopic.php?showtopic=5352

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