Sigma-Tek 22-1280 Vacuum Switch Sticking

[Guitarmaster]

Hey Guys.  

I replaced the vacuum switch two years and about 150 hours ago.  My low vacuum warning has been intermittent and I finally got around to diagnosing it.  

I seems like the internal diaphram switch is getting stuck when flown and is refusing to return to the LOW VAC position.  If I tap on the unit gently, it will begin working again.  Obviously I would like this to work as advertised.

Does anybody know if there is a way to clean these switches?  Goona call and talk to Chief Aircraft, from which I bought the switch, tomorrow.

[Marauder]

9 minutes ago, Guitarmaster said:

Hey Guys.  

I replaced the vacuum switch two years and about 150 hours ago.  My low vacuum warning has been intermittent and I finally got around to diagnosing it.  

I seems like the internal diaphram switch is getting stuck when flown and is refusing to return to the LOW VAC position.  If I tap on the unit gently, it will begin working again.  Obviously I would like this to work as advertised.

Does anybody know if there is a way to clean these switches?  Goona call and talk to Chief Aircraft, from which I bought the switch, tomorrow.

You talking about the silver gizmo on back of the AI or DG? I seem to remember using an electronic contact cleaner on mine. The one safe for plastics. 

[Marauder]

The other option is get rid of that vacuum system! LOL!

[Guitarmaster]

You talking about the silver gizmo on back of the AI or DG? I seem to remember using an electronic contact cleaner on mine. The one safe for plastics. 

Yes. That's the one.

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[Guitarmaster]

The other option is get rid of that vacuum system! LOL!

If only!

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[Piloto]

In between the screw terminals there is an adjustment screw that sets the vacuum threshold. You can adjust the threshold for a lower vacuum pressure. I adjusted mine using a vacuum gauge connected in parallel and reading continuity at the terminals. For vacuum source I just sucked by mouth on the switch.

José

[Guitarmaster]

9 hours ago, Piloto said:

In between the screw terminals there is an adjustment screw that sets the vacuum threshold. You can adjust the threshold for a lower vacuum pressure. I adjusted mine using a vacuum gauge connected in parallel and reading continuity at the terminals. For vacuum source I just sucked by mouth on the switch.

José

Thanks for the idea Jose!  It's not that the threshold is incorrect, it's that it won't make contact (sometimes) when the vacuum drops.  If I tap on the side of the case, it will then make connection. 

[Piloto]

1 hour ago, Guitarmaster said:

Thanks for the idea Jose!  It's not that the threshold is incorrect, it's that it won't make contact (sometimes) when the vacuum drops.  If I tap on the side of the case, it will then make connection. 

I had exactly the same problem and that is why I lowered the threshold. The switch threshold varies by itself.

José

[Guitarmaster]

I had exactly the same problem and that is why I lowered the threshold. The switch threshold varies by itself.
José

Ahhhh. Ok. I'll give it a try!

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[glenn reynolds]

I just removed my sigma tek 22-1280 switch from my plane so I have a spare if you need it.  I installed the garmin G5 so the vacuum system is now in a box in the hanger.  I'm not saying you should remove your vacuum system, just that it is always nice to have spares.  glenn