[Heathkit] IM-2420 Freq Counter problem
Kevin Ward
n2ie at arrl.net
Thu Sep 25 22:26:25 EDT 2014
For starters I'll assume you have checked all the power supply
voltages. Strange things can happen when they are "almost" right.
It seems to me that the least significant digits are all correct. That
will not be the case unless all the counting circuits are doing their
job(s). What's left are the display circuits; the latches and drivers,
which turn on/off the segments in the displays.
Look at all the wires or traces between the driver chips or transistors
and the display board or chips. I bet you will find cold solder joints
or open connections in this area.
Kevin N2IE
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