Monday, November 16, 2015

Paradise problem puzzled!

Paradise problem puzzled!  Yesterday I posted about the clock kit I was building, and how the prescaler had a problem that needed to be troubleshot.  Well, this morning I found the problem: a bad trace on the printed circuit board.  I soldered in a jumper, about a quarter inch long, and presto!  The prescaler is now working perfectly, giving me a beautiful 1 Hz (one pulse per second) signal.  That 1 Hz signal will drive the seconds counter, which is the next part I'll be assembling.

I was surprised that it turned out to be a circuit board problem.  There must have been a tiny break in the trace, but I couldn't see it under the solder mask.  I found two components whose leads were very close together, that were supposed to be connected (but weren't), so the break had to be somewhere in the quarter inch or so between them.  That little jumper did the trick nicely.  Troubleshooting it was actually fairly easy: one component was a resistor that showed a signal on the end that was supposed to be connected to the base of a transistor.  That base showed no signal at all.  Straight wires (or circuit board traces) aren't supposed to behave like that :)  Once I observed that anomaly, finding the actual cause was easy...

1 comment:

  1. This combines your love of electronics and wildlife! http://xkcd.com/1604/

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