[volt-nuts] HP419A Meter Pegged to Right

DaveH info at blackmountainforge.com
Wed Nov 12 02:01:09 EST 2014

The sadly missed Kevin Lightner did electronic music synthesizer repair and
had an interesting technique for cleaning older electronic circuit boards:


No chance for oxidation as the boards were dried immediately with compressed
air. An amazing amount of spilled beer, cigarette smoke and other crud
washing off...

Kevin's old website is here:


Analog music synthesizers are somewhat on-topic as every parameter is
voltage controlled and in the case of frequency (an exponential function)
the requirements are very very precise. The voltage applied is one volt per
octave change and errors of 0.2% can be detected easily. Voltage stability
is also important as these modules need to track over normal room
temperature fluctuations.



> -----Original Message-----
> From: volt-nuts [mailto:volt-nuts-bounces at febo.com] On Behalf 
> Of Chuck Harris
> Sent: Tuesday, November 11, 2014 21:17
> To: Discussion of precise voltage measurement
> Subject: Re: [volt-nuts] HP419A Meter Pegged to Right
> There are certain things that must be done/considered before
> washing old electronics:
> 1) remember there is lots of lead that might not be wanted in
>     your dishwasher.  If you choose to use the DW, buy a lead
>     test pen for afterwards.
> 2) tek always suggested removing the paper insulator tubes from
>     the old FP style of can electrolytic cap prior to washing.
> 3) a large cardbord box, with a 60W incandescent light bulb, and
>     a muffin fan makes a dandy convection oven for drying washed
>     electronics.  There should be a couple of holes in the box
>     to allow moisture to vent out, and fresh air in.
> 4) electronics can't tell when you get it too hot, unlike your
>     head, be careful with the hair dryer.  It can easily get
>     parts hot enough to damage them.
> 5) power transformers don't like being exposed to water and
>     especially to detergent.  Detergent inside of a power
>     transformer can instantly turn a working CRT filament
>     winding into one that has a low resistance leak to another
>     winding/ground.  Many a power transformer has been ruined
>     that way.
> 6) a dishwasher is a deluge of water, more prudent cleaning
>     is done with a gentle shower of water, directed towards
>     parts that don't mind getting wet, and away from parts that
>     do.
> -Chuck Harris
> Stan Katz wrote:
> > That clinches it. Brooke's Tek tour reminded me that I have 
> on file a
> > "Service Scope" from Tek entitled "Washing Your Tektronix 
> Equipment". I can
> > follow those instructions less the drying for 24 hours in 
> an oven at 125F.
> > Doing so will probably have me kicked out of the house by 
> the wife. A hair
> > dryer will have to suffice.
> >
> > The use of a dishwasher, which I could pull off without 
> being found out by
> > my spouse, does require removing all the pots. Anyway, I think that
> > dishwashing is most appropriate for boards with all surface 
> mount chips.
> > Forty year old electrolytics (all of which surprisingly 
> have tested good)
> > might balk at being machine washed.
> >
> > Stan
> >
> > On Tue, Nov 11, 2014 at 11:34 AM, Brooke Clarke 
> <brooke at pacific.net> wrote:
> >
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