Hi Ross

- Yes. The vacuum is fine.  Drops to 2E-6 from 3E-9 as expected when the needle valve is opened. 
- Checked SES cables and they are good. Will check the voltage on it, thought I do not expect any issue there. I see some noise on 46cup if I pull the SES cable off but that is expected without suppression. 
- Ion source control board is fine. I checked all the voltages, Amps etc. Emission is good. All is well on that front. All the LEDs are bright and green. 
- Source is clean and nice. Filament is good. Swapped that one too just in case. The gas inlet hole on the source plate is open. The exit slit is clean and is in position.
- Communication between Isodat and Delta Plus is just fine too. 

Since my last mail:

- I swapped all the possible cards - GPIB, 2 Data loggers, DAC, ADC, SES - from another mass-spec. 
- I checked and swapped Power distribution and Magnet control boards. I went further and tested the voltage right at the magnet. The voltage jumps with steps just fine and a mag scan (500 - 12000steps) increases the voltage from 2-24 volts uniformly. So, the controller is good, the magnet is good. 
- All the outlets on the power distribution board supply 230v even. No hiccups there.  
- The power regulator gives out 5V and 24V.
- I swapped the computers,  GPIB cables and connected the GPIB to a different computer, a different version and both. The problem stayed with the mass-spec. 

So,  currently my trap is shut :-)

The solution may be a very simple one and is right in front of me or may be not!  Something quit in the middle of the night and we don't know what. We will find it eventually (hopefully).

Thank you all for raking your brains for me. Will keep you posted. 

Regards
Madhav 



-----Original Message-----
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf Of Ross Beaudette
Sent: Wednesday, March 22, 2017 2:10 PM
To: [log in to unmask]
Subject: Re: [ISOGEOCHEM] Delta Plus Flat Lined

Madhav,
    Gerry has the right idea.  I'd also add the following:
-can you see a change in vacuum once gas is introduced?
-I've seen in the past on our 252 that if the SE suppression cable is loose, all beams will fail.  So, check that you have the (I think) -165V or so on it.
-I've also seen that if there's a piece of debris on any of the cups, no beam.  I've had to flush out the cups with pure N2 before.  
-Ion source control board will fail.  Make sure all LEDs are green.  There are two red-one for a box/trap short, and one for ?? Look carefully, as all the green LEDs may not light either.  
-there's a reset button on the ISCB.  Resetting that may help.  Caution:  Turn off HV when dealing with this board! 

Hope this helps,
Ross