25 Jan
2012
25 Jan
'12
12:35 p.m.
On 01/24/2012 03:43 PM, Tony Duell wrote:
I agree 100%. Last night I repaired an HP 5340A frequency counter
and a Tek 7834 oscilloscope frame. (both glorious instruments) I had to
trace through a fair amount of circuitry in both cases, and I learned a
lot about both designs.
I can understand that. I've also learnt a lot from jhaving to understand
devices in order to repair them.
The
advantage of the signature analyzer (SA) was you can deal with
circuits that have feedback loops more easilyand without the need to
fully understand the operation of the circuit. For example servicing
And that is precisely why I don't like it. I feel you can only reapri
something -- and know you've repaired it -- if you understnaf how it
should work, know what it's acutally doing, and then figutre out what
could cause the behaviour you're obseerving.
Signature analysis doesn't seem to help with this.
In the "credit where credit is due" department, I had a kind assist
on the 5340A from Dan Roganti who was here at the time. He kept telling
me to look at the Range switch, and I kept saying it couldn't possibly
be that switch contact making partial connection when it shouldn't have
Again I know what you maean. I've had my fair share of 'impossible'
faults over the years.
In the case of the 3456A, though, it's an
instrument from a working
lab run by a friend of mine, and he lacks the budget to have it
repaired, and I just want to get it working as quickly as possible to
help my friend, by any method necessary. The alternative would be to
loan him my beloved 3458A, but that beautiful instrument isn't leaving
my sight! ;)
:-)
I susepct (never having tried it) that singature analysis (to a rpeairer)
is like a monostable (to a digital hardware designer) or a goto (to a
programmer). All are useful (and my be the nbest solution) if used
intellegently, all are capable of making a right mess of things if you
don;t think about what you are doing.
I know from your postings that you'd use one sensibly, I hope I would
too. Cerainly if I saw an HP signature analyser at a low price I'd buy it
(I sort-of collect odd/interesting instruments), but I doubt it'd replace
a logic analyser as my faultfinding instrument of choice...
-tony