I think the problem is in the Emission control board. Probably the trim resistor.
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf Of gerard olack
Sent: Wednesday, March 22, 2017 4:38 PM
To: [log in to unmask]
Subject: Re: [ISOGEOCHEM] Delta Plus Flat Lined
Ok, check the cable coming from the amplifier housing ;)
Yes, I'm guessing you've done that and checked the LED's on those boards too...
When you say no reading, "0" or something around "-256 mV". "0" is no ion beam getting to cups. "-256" is everything is below the hard cutoff, like when someone does an electronic offset with gas in the source. In newer toys, software controlled. Not sure what it is in your case.
On 3/22/2017 2:09 PM, Machavaram, Madhav wrote:
> 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.
> -----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
> 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,