ytsestef Posted September 4, 2012 Posted September 4, 2012 (edited) Pin #7 of the Shift Register #4 of a DOUTX4 module is outputting -0.73V (with LED connected) when it should light up. All the other pins of all the other shift register work correctly (about 2.5V with LED lit) I already checked LED polarity and resistors... Edited September 4, 2012 by ytsestef
NorthernLightX Posted September 4, 2012 Posted September 4, 2012 A negative voltage on a module that should only have +5v and GND? Maybe a busted shift register? Have you tried swapping ICs?
Imp Posted September 4, 2012 Posted September 4, 2012 Since pin7 is next to a GND Pin, it could be a short between those two. Are you sure you measured against GND?
ytsestef Posted September 4, 2012 Author Posted September 4, 2012 Found it, guys. It was the bridge. On mike's PCBs, there is a bridge for the last pin of the last Shift Register that should be soldered underneath the PCB. It had come off and the SR voltage never reached the resistor. I soldered it again and all is good :) Thanks
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