3PDT Failure

[benny_profane]

I've just had a 3PDT from a previous build (about a year or so old, regular but not 'strenuous' use) fail. The switch mechanism works as before (from a tactile perspective, at least), but the connection between poles 8 and 9 is no longer being made. Every other switch element behaves as expected (including the connection from 8 to 7). Is this normally how they fail? Replacement is simple and easy, but I'm a little curious about what exactly went wrong.

[movinginslomo]

the part supplier and source of the part. Tolerances may be off, plastic quality, etc. Cheap parts can just fail

[jimilee]

I've just had a 3PDT from a previous build (about a year or so old, regular but not 'strenuous' use) fail. The switch mechanism works as before (from a tactile perspective, at least), but the connection between poles 8 and 9 is no longer being made. Every other switch element behaves as expected (including the connection from 8 to 7). Is this normally how they fail? Replacement is simple and easy, but I'm a little curious about what exactly went wrong.

Did you test it with a meter? Happened to me once, I just had to reflow pin 4. Same type situation too.


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[benny_profane]

Did you test it with a meter? Happened to me once, I just had to reflow pin 4. Same type situation too.

I ended up taking the 3PDT and bypass board assembly out of the box. Tested continuity on everything and determined that those two pins with the only ones without continuity. Reflowed the joints with no change. Then I removed the solder from the pins and checked for continuity; connection was back! Resoldered those pins and reflowed the rest for good measure. Rather curious, but glad it ended up working again.

I imagine that unless a pin gets disconnected from the internal mechanism, single pin pole failure seems unlikely. What is the most common way(s) that 3PDT switches end up failing? Pins breaking internally? The switch mechanism making unreliable connections? Something else?

[jimilee]

Mechanical, the metal would separate from the plastic. I've never seen a switch out right fail without overheating it when you're soldering the wires.


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[benny_profane]

Mechanical, the metal would separate from the plastic. I've never seen a switch out right fail without overheating it when you're soldering the wires.


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Gotcha. Yeah I sorta figured it either fails at install or not for a long time. That's why this seemed a little weird to me. Odd that it lasted a year+ without issue and with a joint under no mechanical stress.

[jimilee]

Mechanical, the metal would separate from the plastic. I've never seen a switch out right fail without overheating it when you're soldering the wires.


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Gotcha. Yeah I sorta figured it either fails at install or not for a long time. That's why this seemed a little weird to me. Odd that it lasted a year+ without issue and with a joint under no mechanical stress.

Very true.


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