msg wrote in message
...
N Cook wrote:

snip

Let this be a lesson to anyone in the UK -
DO NOT store Rochelle crystal cartridges in lofts or sheds.
The crystal must be hygroscopic.

snip

Anyone reckon I can rob the crystal from a piezo ceramic pickup to fudge
a
functional and "as original" repair?
I assume piezo-ceramic is not prone to this problem over 40 years.

FWIW, I have seen a number of grow-your-own Rochelle salt crystal
experiments on the web; the process seems rather straightforward and
the results look good if the work is performed with care. If you
were successful with this cartridge and posted your work I'm sure
it would attract a lot of attention :-)

Regards,

Michael



I reckon it is possible to convert piezo cartridges.
I have dozens of later N.O.S Sonotone mono pickups, but have never looked
inside one.
http://home.graffiti.net/diverse:gra...et/ful-fi3.jpg
The central image is the active section. Not obvious in pic but the 2
vertical sections are each metal/piezo-ceramic/metal sandwich like bi-metal
strip in fabrication, set in quadrature, so a pair of pickups, but
electrically combined for mono output.
So although these are pinned out as mono, just rewiring the innards and
adding a pin would presumably convert to stereo.
Electrical contacts are via fine sprung strips set in a black rubber pad
like the white one shown, there is also another such black block removed,
they hold in place in the casing.
The lower creamish joining part is the plastic cradle/saddle for the stylus
shaft.
Cutting down the rubber pads a bit and sorting out some contacts and gluing
in the ful-fi casing will probably work, whether capacitance etc is wrong
I'll wait and see.

The kid's clothes peg, 1 inch long was just right as an insulated clip to
hold a pair of contacts, temporarily, to check on a scope.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/