Did altitude just blow out 2 MPS's?, Put the in my checked baggage...now won't hold vac. Options

[FlacaProductions]

Brought two of my 3 MPS back to L.A. from Indiana while I await the arrival of my LCR55A so that I could do some bench plotting and tuning only to find that neither one of the now holds any sort of a vacuum.

Both ran fine in the car before flight - just needed some adjustment. One has the factory plug replaced with a Tangerine model - the other is still factory sealed.

Did being in the unpressurized cargo area in my checked baggage blow them both?

That would really stink....

Brian

[ChrisFoley]

Here's what I thought of:
The reduced atmospheric pressure resulted in expansion of the aneroid cell, which pushed the diaphragm outward, like happens during use on overrun, but with more force.

More than likely the diaphragms were close to failure already. They almost always fail at the edge of the supported perimeter area because the casting has a sharp corner there.

[JeffBowlsby]

Here's what I thought of:
The reduced atmospheric pressure resulted in expansion of the aneroid cell, which pushed the diaphragm outward, like happens during use on overrun, but with more force.

More than likely the diaphragms were close to failure already. They almost always fail at the edge of the supported perimeter area because the casting has a sharp corner there.

This^^^

An interesting dilemma. I think the aneroid cell would have expanded, pushing against both the diaphragm armature and the sliding coil armature. The diaphragm, cell and coil may have been distorted enough to kill one of all of them, or maybe not. Each one can be tested.

https://www.engineeringtoolbox.com/docs/doc...ir_pressure.png