[Hallicrafters] Bumblee Caps.

[Richard Knoppow]

----- Original Message ----- 
From: "William Hawkins" <sgr4436 at yahoo.com>
To: <Hallicrafters at mailman.qth.net>
Sent: Friday, November 02, 2012 7:11 AM
Subject: [Hallicrafters] Bumblee Caps.


In 50 years of electronic troubleshooting, I have run into 
those caps in everything from an RCA videotape recorder to a 
$15 Philco table radio.
They were all bad. Shorted, cases split, off value, leaky 
and more.
I've never seen a manufacturer's name on them.
I've been told they were made by Sprague but I find that 
hard to believe.
The Sprague "Black Beauty Telecaps" were an entirely 
different product and were high quality capacitors.
It seems to me that the bumble bee's must have been very 
cheap OEM products and were sold to many different 
companies.
Gibson did use them as tone caps in their guitars and 
somehow they gained "cult" status. I have a 1956 Gibson 
Console Grande steel guitar which, when I bought it 8 years 
ago, still had the original bumblebee
cap in it. It was shorted. Probably they lasted longer in 
guitars because there is no significant voltage there.
Sorry that Hallicrafters used them too.
There is a lot of "folk lore" among guitarists about those 
caps.
Blake
N4YCQ

     They were indeed made by Sprague. Check old catalogues. 
Sprague made both Black Beauty and Telecaps. They look the 
same. The BB's have the code stripes on them which was an 
industry standard at the time. BB's were oil-filled and that 
was part of the problem. The filling was done by means of a 
tube also used to hold the lead on one side.  The solder for 
the lead sealed the tube.  If too much heat was applied when 
installing the cap the solder melted enough to cause a slow 
leak.
     There may have been other problems: all the BB's I've 
dissected had distorted windings. Perhaps done to adjust 
them but I think more likely unintended. Not all molded body 
caps of the period were bad and Sprague also made a similar 
cap in a dipped resin case and these seem not to have had an 
unusually high failure rate.  The winding was plastic 
impregnated paper and should have lasted longer than the 
plain paper dielectric in the wax paper type caps.  Life 
limitation due to degradation of the paper was well known at 
the time and all manufacturers of paper caps supplied 
derating charts showing life expectancy as a function of 
applied voltage.  The higher the ratio of rated to applied 
voltage the longer the expected life was.  Oil filling was 
supposed to reduce this effect.
     I think Sprague made some blunder in their 
manufacturing procedure. BB caps are found in some very high 
quality equipment and are not always bad but usually are and 
are worth replacing on sight.  Beside, modern film caps have 
much better characteristics than these old caps did when 
they were new.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com