Hi Jerome,

It looks like a short between filament and ionization chamber. Disconnect
all the wires supplying ion source and test it by ohm-meter.
Greetings from hot Lublin ( 33C), SE Poland,
Stan

At 18:04 14.07.01 +0200, you wrote:
> >    We are encountering problems while using a Finnigan MAT 252.  The
> > emission LED is not turning on.  The cathode reading and trap emission are
> > both hovering around zero, and the emission is reading "1.", which I
> > presume is the same as no emission.  The electron energy is 0.8 eV, while
> > it is usually around 63 eV.
> >    However, the high voltage LED is lighting up. The high voltage is just
> > under 8kV, and the trap is at 70.0 eV.  Both of these values are typical.
> >
> >    We have tried changing the filament and checked the source pins for
> > shorts, but the problem persists.
> >   Can anyone offer us guidance or suggestions?
>
>Gavin, if I remember well, these symptoms are those that we experienced
>on our 252 about a year ago. The reason was a dead condensor on the high
>voltage electronic board. Once localised, cheap and easy fix.
>
>- Jerome Chappellaz.