On Nov 22, 8:36*am, "N_Cook" wrote:
What would cause the failure of one half of a 4 year old 12AX7 ? A very
careful owner.
One half tests out fine but for half using pins 1,2,3 cannot get any zeroing
on the tester even setting current down to 0.5 mA or less and for any grid
voltage setting. Can't see any obvious internal weld failure.

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

Hi,

Given that it is dead, if you really wish to find out you could always
crack & remove the glass and then check the internal connections.
Nothing to lose!