Troubleshooting with a Frequency Counter

[Tony Duell]

> 
> 
> I was just thinking about troubleshooting, and am curious if anyone has used a
> frequency counter for troubleshooting? It seems like it would be another way to
> find out if there are clock or data signals besides using a scope. And
> reasonable frequency counters shouldn't cost more than $50.00 or so including
> shipping.

It will tell you if a signal is changing, sure. So it's useful for 
checking the clocks, and I suppose for seeing if data/address lines are 
changing at all. But it won't tell you if said data/address lines are 
doing the right thing.  OK, you know the bottom 8 address lines are all 
changing, but you don't know what addresses the processor is actually 
acessing, for example.

My most-often-used test instrument, an HP LogicDart does display the 
frequency of the input signal, as well as letting me capture it 
(high/low/undefined states, not a true 'scope type of capture). I've used 
that facility for checking clock waveforms, and thus finding the 
open-circuit crystal in my HP9820. But that reading on its own is not 
enough to go much further.

-tony