Dear Sven, John, Wolfram, Mark, Robert and others who shared their 
experince on my problem,

now the source is OK.
First we tried whether it was a software problem or not, but there was 
any improvement.
Then Vladimir Feinberg suggested to remove the cathod from the source 
and to test it for High Voltage (HV). We did it and the HV was OK! So we 
learnt that the problem was with the cathod (or nearby).
Then we installed a new cathod and now it works!!!

Practically we do not understand why, because we have examined the used 
cathod and it looks to be good. The filament is good and there is no any 
visible fault of the cathod. But anyway, it caused the problem.

Best regards
Istvan

Sven Steinbrenner írta:
> Hi István,
> did you measure for shorts in the position with relaxed springs?
> If you push the source base plate to compress the springs, it could be 
> that the screw (mounted the filament at the ionization housing) is 
> touching the springs.
>
> One more possible thing is the Spacer ring; quartz glass, 6 x 4.1 x 4 
> between the trap and ionization housing. This spacer could be damaged, 
> a small crack is enough, or is still dirty.
>
> Good luck,
> Sven
>
> Fórizs István schrieb:
>> Dear Finnigan User Colleagues,
>>
>> recently we have cleaned the ionsource of our Finnigan delta plus XP 
>> mass spectrometer (as ususally at the beginning of the year). But the 
>> ionsource does not want to work properly after switching on.
>> 1) the HV is 0.33 kV instead of 2.9 kV.
>> 2) The current on the anode (trap) is 0 mA, while on the ionization 
>> box it is the maximum, 1.5 mA. There should be some 0.7 mA current on 
>> the trap. We have checked the positions of both anode and cathod and 
>> found them to be good.
>>
>> We have disassembled  and checked the ionsource two times, but have 
>> not found any unusual. The anode (trap) connection is good (and all 
>> the other connections) and there is no shortcut in the ionsource (on 
>> the front panel of the MS the green LED of "Accel Voltage" is on).
>> The green LED "Emission" on the front panel is on for a moment just 
>> after switching on the source, then turns off. Why?
>>
>> If any of you has met with this symptome and has an idea about it, I 
>> would appreciate very much his/her help.
>>
>> Best regards
>> István
>

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Dr. FÓRIZS István  ..........  Istvan FORIZS Ph.D.
Magyar Tudományos Akadémia Geokémiai Kutatóintézet
Institute for Geochemical Research, Hungarian Academy of Sciences
Cím/Address: H-1112 Budapest, Budaörsi út 45.   Hungary
Tel./Phone: (36-1)-309-2600/ mellék/extension 1151
Fax: (36-1)-319-3137
Http://www.geokemia.hu/people/forizs_hu.html
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