[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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