[R-390] HP410B Intermittent(s)

[mikea]

On Mon, May 25, 2009 at 12:13:33PM -0500, Don Reaves wrote:
> 
> > get go.  Removing the old gucky solder then liquid flux and heat 
> > seemed to give a ok joint.  It was surprising to see that kind of 
> > problem inside of an HP instrument.
> > 
> 
> Not unheard of.  I once found the problem with an HP-200R with intermittent
> output to be that a b+ line leading from the power transformer had never
> seen a hint of solder.  The wire was wrapped on the transformer solder lug,
> and it probably worked OK for a few years, then slowly oxidized.  
> 
> A slight variation of the Stockdale technique to restore operation of a
> BC-375 worked on the HP-200, before the proper repair was implemented.
> 
> http://www.youtube.com/watch?v=TBXmVqcAP6M  (at about 2:30 in this clip)

I'd totally forgot that part of the movie. Now I have to get coffee out
of the keyboard on the other computer. And send my pants to the
cleaners. 

Folks here may be interested to know that the USAF (and, presumably,
other services) had a 300-Baud modem with mechanical resonators, back in
the late 1960s. It had glowbugs, too, as well as a regrettable habit of
ceasing to produce tones. When it stopped whistling, then it was time to
whack it _HARD_ on the lower right corner of the front panel to restart
the resonators with a mechanical shock.

We replaced that critter, but nowhere near soon enough for me, with a
Rixon SeBit 24 that was about the size of a paperback book -- lots
smaller than the 6 rack units that modem ate, and lots cooler, too.

-- 
Mike Andrews, W5EGO
mikea at mikea.ath.cx
Tired old sysadmin