FYI on the Sansui TU-9500 power switch

[mattsd]

I recently got a TU-9500 in for repair that had a problem with constantly flickering lamps, turns out the power switch was the cause, it would measure between 1K ohms to 15K ohms in the closed position. The power switch is an interesting setup, the toggle actuates a basic plunger style switch rather than using the toggle switch directly. The plunger switch is also sealed so it cannot be cleaned. After doing some research, I found one that looked identical in the datasheets to the old one so I pulled the trigger and got it today. I'm happy to report it is a perfect drop-in replacement for the old switch! Part number from Mouser is 653-V102C24 and Digikey is Z5104-ND.

Old vs new:

New switch in place, looks identical except the terminals are slightly longer.

 

[rickb119]

Good find.

 

[Sansuiman]

Very nice, though I am quite surprised they used micro switches of that type. I didn't even realize those were available at the time the 9500 was manufactured. I'd always thought those came along in the 80's as they used to be common in many printers and copy machines, as well as in some automotive applications and as limit switches in some home appliances and machinery. I've not seen anything that used them from the 70's before, so this is a first.

In fact, many older computer mice and trackballs used those same switches for the buttons as they provided very good tactile feedback and were incredibly reliable when not switching large loads. In power switching applications, they tend to eventually get internal contact burn from the combination of oxidation and heavy load switching.

 

[LBPete]

That type of micro switch has been around a very long time, at least since the 1950s and probably pre war.

- Pete

 

[612electric]

Thanks...I had a TU 9500 and had to replace a lot of parts due to water /humidity damage .Info like this is always welcome.

 

[Sansuiman]

Pete, thanks for that tidbit of information. Never realized that design went back that long. Learned something new today.

 

[LBPete]

They are older than I thought. From Wikipedia:
"The first micro switch was invented by Phillip Kenneth McGall in 1932 in Freeport, Illinois, patent 1,960,020. McGall was an employee of the Burgess Battery Company at the time. In 1937 W.B. Schulte, [1]McGall's employer, started the company MICRO SWITCH. The company and the Micro Switch trademark has been owned by Honeywell Sensing and Control since 1950.[2] The name has become a generic trademark for any snap-action switch. Companies other than Honeywell now manufacture miniature snap-action switches."

- Pete

 

[Sansuiman]

Well, that shocks the hell outta me. I'd not have believed the level of minaturization to make a switch in that form factor existed in the 1930's. And I'm hard pressed to think of a finished product that would've needed such a small switch that era.

I have seen snap action switches in a larger size with a round metal actuator and bakelite body from some 1950's era equipment, so perhaps there were earlier, larger designs that were superceded by the micro switches we are familiar with now. This is all off topic anyway, but still interesting to me to find out how long they have been around nonetheless.