Ion pump issue...

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RobertMendelsohn
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Joined: Mon Jul 20, 2020 4:58 pm
Real name: Robert Mendelsohn

Ion pump issue...

Post by RobertMendelsohn »

I have a 20L/s Varian StarCell and a MiniVac controller that refuse to work; I've jumpered 3-7 as the manual says since I have no interlock, and the MiniVac powers on and the HV LED comes on, but no voltage/current indication.

My thought: controller is busted acquire a new one. AFAIK, ion pumps are pretty rugged? And I could see the innards were very clean (supposedly a new one). Let me know if you have better ideas! I'd rather repair this unit than buy a new one...
RobertMendelsohn
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Joined: Mon Jul 20, 2020 4:58 pm
Real name: Robert Mendelsohn

Re: Ion pump issue...

Post by RobertMendelsohn »

Additional info: the LEDs that indicate the voltage/current flicker repeatedly, then don't flicker.

A look at the internals reveal no obvious sign of damage.

Possibly an inability to strike an arc?
John Futter
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Re: Ion pump issue...

Post by John Futter »

Arcing at startup is very common on Ion pumps
i try to get them below 10^-6 millibar before starting a new or one that has been at air for some time
a heafty cook out also helps but know the spec on your magnets before cooking them 250 degrees celsius plus won't hurt if the magnets can handle it
Jerry Biehler
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Re: Ion pump issue...

Post by Jerry Biehler »

On SEMs ion pumps are pretty notorious for not wanting to start up after they have been sitting, especially at air. Like John says, do a bake out, pull the magnets off and get it as low as you can preferably with a turbo or ln2 trapped diff.
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