One more potential story/hypothesis/solution to the HV tripping 
problem.  It is possible/likely there are multiple causes of what so 
many of us seem to have experienced:

Several months ago our Delta Plus XP (with two source pumps, generally 
running at 1.6e-6 mBar in CF mode) began tripping to 0.34 kV with 
increasingly alarming frequency (increasing to an "event" every several 
days).  This led to a decision to advance by several weeks the annual 
maintenance to clean the source.  Then the filament burnt out, 
requiring immediate maintenance.  So I (1) replaced the filament, (2) 
cleaned the source thoroughly (including scrubbing all metal parts, 
filing and annealing ceramics), and (3) replaced a burnt out source 
heater bulb (see Marion's comment), and (4) pump maintenance, etc.  The 
problem has not recurred for 6 months now.  I suspect it will again 
when the source is sufficiently dirty/wet? to arc across ceramic 
insulators.  I think in this case it was simply a dirty/wet source, 
which should not be ruled out entirely as the cause in some cases.

Jonathan Wynn.

On 2 Dec 2005, at 08:27, Marion Hoch wrote:

> Hey Linnea,
>
> we have the same problem every three or four months. The HV turns off. 
> You can restart it but after a few hours it trips off to 0.34 KV 
> again. The first time it happened we checked our power supply system 
> for nearly one week. But we could not find any fault although the HV 
> turned off several times during that week. But now we have a very 
> simple explanation. We found that one of the heaters did not work any 
> more. We changed the heaters and the system was running without any 
> problems. So the last two or three times when the HV turned off I 
> checked the heaters and in all cases one of them were broken. After 
> changing the heaters we had no problem anymore with the HV. This might 
> be a very simple solution for your problem but in our case it works.
>
> Good luck
> Marion
>
>
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