Wow, Im on an electronics forum!! So cool!

[noquacks]

People,

Glad to be here, Im expecting to learn so much. Well, 1st problem- Trying to locate a single pole hinge lever/roller lever snap action switch. Old one is a Cherry, E-14 (link similar is here:

http://www.mouser.com/ProductDetail...=/ha2pyFadugwji3neNyMejuPT9UdgJuTaXZFiebqt1U=

Thing is, they require one to buy 800!!! Sheesh. So, anyone know another place to buy 1 or even 2 or 3?

Now, lets say my old one is still good- Im willing to test it for resistivity. I get 0.8 ohms so far between the common spade end and other end when snap lever is depressed. Strange thing I dont understand is with lever free (not depressed), I get also a reading on the OTHER spade connector on the double terminal end. I am confused. Is my "old" switch maybe still OK?

Thanks!

 

[(*steve*)]

I'd be looking for something from an alternate manufacturer. lever action microswitches are not uncommon.

 

[duke37]

The switch should conduct from the contant one end to either one or the other contact at the other end.
0.8 ohm seems to be too high but perhaps it is the meter leads.

Any contact betweent the two adjacent terminals means the switch is dead.

Microswitches are very common. They come in various standard sizes so get the right one.

 

[noquacks]

Thanks, people. Im trying to locate similar. I redid the tests, and getting now about 0.4-0.5 ohms (meter/terminals of meter are much steadier than last nigh, I think). No reading between the 2 adjacent ones. probably still good, you think? Also, putting new blade terminal clips on the burnt ends. Then, I will test it all out.

 

[noquacks]

The switch should conduct from the contant one end to either one or the other contact at the other end.
0.8 ohm seems to be too high but perhaps it is the meter leads.

Any contact betweent the two adjacent terminals means the switch is dead.

Microswitches are very common. They come in various standard sizes so get the right one.

Meter is new, so probably not terminal ends of meter. Also, is 0.5 a better value than the 0.8 I reported yesterday?

 

[(*steve*)]

What resistance do you get when you touch the two leads from your meter together?

Subtract that from the reading when you measure the switch to get its real resistance.

 

[duke37]

The connection should be from the remote terminal to either one or the other adjacent terminals which I think you have.

If the terminals are burnt, the contacts inside will probably also be burnt which could give a significant resistance. The switch should be replaced with new clips to keep resistance low.

Microswitches are very good for normal puposes, they punch well above their weight because of the snap action, however, they were rejected for the safety system on an X-ray set since they could stick.

When you get your new switch, have a look inside the old one, the mechanism is quite interesting.

 

[noquacks]

What resistance do you get when you touch the two leads from your meter together?

Subtract that from the reading when you measure the switch to get its real resistance.

Wooooowwww! I learnt something new- man, Steve, I get about 0.3-0.4 ohms, so if I subtract, I get effectively about 0.1 ohms for my switch? Is that a good reading? Im hoping so! Never woulda figured.

 

[noquacks]

The connection should be from the remote terminal to either one or the other adjacent terminals which I think you have.

If the terminals are burnt, the contacts inside will probably also be burnt which could give a significant resistance. The switch should be replaced with new clips to keep resistance low.

Microswitches are very good for normal puposes, they punch well above their weight because of the snap action, however, they were rejected for the safety system on an X-ray set since they could stick.

When you get your new switch, have a look inside the old one, the mechanism is quite interesting.

Terminals on switch are not burns at all- its the copper twist ends of the blade ends of those wires that are burnt, so we should suspect/blame the wires so far, not the switch (maybe I wasnt clear earlier about what actually was burnt).

Oh- heres what they look like based on the diagram I found from Cherry:

http://www.cherrycorp.com/english/switches/general/e_sp.htm

So, update: I replaced the burnt ends of the wires with new/ends, and started up the car, cold ac. Tested voltage at the switch ends and get a steady 13.04 volts, for about 2-3 minutes. Then, I tested V at fuse, and got 12.60 or so steady. Tomorrow, I drive it to work with ac on all the way!! I will let yous know! man, I hope I got it this time.......

 

[(*steve*)]

Wooooowwww! I learnt something new- man, Steve, I get about 0.3-0.4 ohms, so if I subtract, I get effectively about 0.1 ohms for my switch? Is that a good reading? Im hoping so! Never woulda figured.

It seems to confirm that most of the resistance was in your meter leads.

The next trick is to measure the voltage across the switch when it is turned on and the load attached.

You should read a very small voltage (close to zero).

Also feel the switch after it has been on for a while (several minutes at least). It might feel slightly warm, but it it feels hot to the touch, then something is badly wrong. Anything more than slightly warm needs to be investigated.

If the switch is being used at 12V then feel free to use your finger to feel it. If it's operating from higher voltages, find some other way.

 

[GonzoEngineer]

Newark has stock on that switch.

 

[noquacks]

It seems to confirm that most of the resistance was in your meter leads.

The next trick is to measure the voltage across the switch when it is turned on and the load attached.

You should read a very small voltage (close to zero).

Also feel the switch after it has been on for a while (several minutes at least). It might feel slightly warm, but it it feels hot to the touch, then something is badly wrong. Anything more than slightly warm needs to be investigated.

If the switch is being used at 12V then feel free to use your finger to feel it. If it's operating from higher voltages, find some other way.

First: Yippeee! drove all the way home (20 minutes) with ac on, no blown fuse and cooold ac!!. Thats a good thing. But, I just read your advice, Steve, so didnt have a chance to do this "warm feely" test while driving/at a stop light with car/ac on. I can do this maybe Monday, and let you know.

Only thing- I dont get it- Yes, it IS a 12v switch, as auto ac (just about any auto component) is on 12v. But, how/why should one get close to zero v ACROSS the switch while ON? I already checked V at the switch - one meter terminal on one end, the other terminbal on the one of the 2 ends and get 12v (the other end of the "two" terminal ends I do get zero. Is that what you mean?

 

[(*steve*)]

Only thing- I dont get it- Yes, it IS a 12v switch, as auto ac (just about any auto component) is on 12v.

OK, I interpreted ac as AC.

But, how/why should one get close to zero v ACROSS the switch while ON?

Think of the switch as perfect. When it is off, no power flows through it, when on it provides no impediment to the flow of power.

Now think of it like a valve. Imagine we have a pump (your battery) where the output goes to the valve (your switch) and then to a fountain (your airconditioner). To complete the circuit, the pump draws water from the reservoir at the base of the fountain (just as there is a connection from the airconditioner to the other side of the battery)

If the pump is running and the valve stopping the flow of water, what pressure difference will to see from one side of the valve to the other?

If the valve is allowing the flow of water, what pressure difference will you see across the valve?

OK, lets assume the valve isn't perfect and that it does restrict the water a little -- what effect will this have? The fountain will not reach the same height and less water will flow through the system.

This is the same effect that a faulty switch will have. There will be a voltage drop across the switch (voltage is like pressure). As a result the airconditioner will get a reduced voltage and will not work well.

In both cases, the loss of energy will result in heating, however you don't see that in valves because water conducts that heat away. In electrical circuits, the wires will carry some away, but the device may get noticeably hot.

I already checked V at the switch - one meter terminal on one end, the other terminbal on the one of the 2 ends and get 12v (the other end of the "two" terminal ends I do get zero. Is that what you mean?

No, you place one end of your voltmeter on one side of the switch, and the other on the other side of the switch. When the switch is off, you'll see 12V (essentially the full battery voltage).

When the switch is turned on, you should ideally see 0V, but practically you may see a small voltage. That small voltage is caused by the imperfection in the switch combined with the current drawn by your airconditioner.

 

[noquacks]

Thanks for the extended explanation. So, I did that this morning, and glad to have found that your test comes out GOOD, meaning, 0 volts switch on at that terminal, etc. Looks like we finally did it, Steve (and other helpers here, of course). I cant believe we fixed it wil only a few $ for terminal ends! I was so scared my car's ac was kaput (I have to remember ac on this forum can mean something else....LOL)

I am confident this fix will last a long time. If not, I can come back here!!!

Thanks, people. .