[R-390] HP410B Intermittent(s)

[Jon Schlegel]

Don,

Finally got all the flakies fixed, calibrated the instrument and the 
410B now works great.  It was just surprising to see the 
as-manufactured poor solderability of the terminal boards.  It took a 
lot of effort to find everything.

The 122 Megohm input Z is quite the thing.  Just moving my hand near 
the probe zooms the meter pointer around quite a bit.

Jon


P.S. The Youtube clip is quite the culture shock!




At 12:13 PM 5/25/2009 -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)
>
>
>Don
>
>
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