Meat Plow wrote:
On Thu, 06 Sep 2007 09:01:54 +0100, N Cook wrote:

So many of these lead failures, not solder problems
There must be a better way - at production, yes, using large diameter hollow
tube "beefings" and larger pcb solder pads and holes.
But retrofit ?
I'm assuming the oscillation mode is transverse to the resistor axis rather
than axially rocking. If laid against the pcb then the ceramic "feet" act as
leverage when rocking and if elevated off the board then extra momentum also
amplify the rupture force at the point where the leads go through the board.
This is my latest attempt. I have hundreds of these hermaphroditic
Varelco, Elco, Edac (DERA company, over-shelflife disposal) like in pic
http://www.dhaen.org.uk/vdocs/Onryok...es/varelco.jpg
(in the bag )
I could find no other pics on the net.
The flat part is the mating part so they can mate like 2 finfgers of one
hand rotated 90 degrees and mating twith 2 fingers of your other hand, so no
male/female specificity. A pair of these gold plated brass contacts with one
of the 2 fingers cut off with snips . Matching side with side so when
crimped and soldered to the resistor leads , facing opposite directions,
they are, locked against rocking, against the board.
It will still be a weak point at or in the pcb hole but will they be more
resistant to fracture than the usual resistor lead metal ?

I guess they just don't make them like they used to? I've worked on many
many combo amps and can only recall one failure as you describe and it was
in my own Peavey Artist 120 circa 1975.


I bet that happened because the white gluey stuff they put on to
stabilise the part had dried out and cracked off, same goes for the
smoothing caps. I usually stabilise them with a squirt of high temp hot
melt glue, the woodworking stuff. When it gets hot it goes softer, but
doesn't run off like the clear type does.

I service amps that travel the length and breadth of the country
virtually non stop being professionally used. These failures are just a
part of life, beefing up one area probably means that something else
will fail elsewhere. Plus of course, modern stuff is junk compared to
that which was made 20/30/40 years ago

All IMHO of course

Ron(UK)