Topic: Rebuilding a Keyswitch (electrical contacts)

[TwoTired]

I took a key switch out of my spares collection to show the overhaul process.
This switch came out of a 78 CB550K.  This should be typical of the type found between the instruments which include a fork locking mechanism.  I don’t know for certain if this example is a stock Honda type or an aftermarket type.  The external markings are just some numbers 5.03 and what I assume was the key number 48709.  The key cylinder barrel was missing, but the electrical portion was still intact.  See pic 01

The first step at this point is to separate the electrical section from the steering lock section by using screwdrivers on the release tabs.  See pic 03

There are two of these, one on each side.  Pushing them inward allows separation.
Note the mechanical engagement is keyed.  The orientation must be maintained when it is reassembled.
 See Pic 04

Next is to get at the electrical contacts, taking the switch itself apart.  There are engagement tabs all around the switch housing which must release from the grove that hold it together.  You may need multiple screwdrivers and perhaps feeler gauges to bend the side out just enough to clear the retaining groove.  Beware not to bend these tabs outward too far, as they may well snap crack and fall off. See pic 05

Here is a view of the inside showing the contacts and bridge bars that make the connections when the key is turned.  This switch was probably working fine before a lost key prompted someone to render it worthless by removing the key cylinder, instead of taking it to a locksmith to have a key made.  Still there is a good bit of dirt and congealed lube that may interfere with good current conduction through the contacts.  I did not measure contact resistance before disassembly.  I probably should have.  But, I just didn’t think of it in time.
There is a spring that presses the contact bars onto the contact buttons.  Don’t let it get away. See pic07

See next post...

[TwoTired]

Here is the cleaner I used to get rid of the dirt and old lube.  I’ve no idea if it is still available, and this one is at least 5 years old.  But it is important to use a cleaner that is known safe for plastics.  Other cleaners, such as WD 40, or alcohol, may clean well enough, by may also leach out the solvents in the plastic, making them get brittle in the future.  If the plastic crystallizes, the internal contacts won’t be held in place properly.  It might fail in years, or it might fail next week. See pic 08

The last picture shows the contacts lubed with viscous silicone.  It is quite thick and doesn’t  wander far from where it is placed.  It’s function is two fold.  One; to allow easy movement of the sliding parts. And two; to keep the contacts shielded from corrosive elements in the atmosphere.  If water happens to get inside, the silicone will not be diluted or washed away.  The contact spring pressure will squish it out of the actual conduction path.  The screwdriver poits to one of two keyways  One is larger than the other, so when you put it back together, be certain you have the wide tab in the wide slot.  Also, this swtic is assembled with the spring contacts down toward gravity.  The right side (in the picture) is placed upon the left and pressed straight down.  See pic 09

The thing goes back together far faster than when taking it apart, which no doubt made for quick production on a mass scale.

That’s it for this type of switch.  It is certainly possible to find other internal mechanical arrangements for contacts.

Hope this helps.

[TwoTired]

A warning about heat while soldering. It can melt the plastic and change the contact relationship inside the switch.
It is precisely why they are riveted,rather than soldered on factory assembly.

Cheers,

[BobbyR]

Very nicely done. I am sure all of our switches need a cleaning by this time.

[Picasoo]

Very usefull...thanks!!

[grcamna2]

Two Tired,
     Would you recommend a product named "Tronic Kleen" from Four Star Chemical or how about Tuner(for old TV's)cleaner spray from a place like Radio Shack as the liquid cleaner to remove the built up junk on the switch contacts ? They are both safe on plastics.

[TwoTired]

Two Tired,
     Would you recommend a product named "Tronic Kleen" from Four Star Chemical or how about Tuner(for old TV's)cleaner spray from a place like Radio Shack as the liquid cleaner to remove the built up junk on the switch contacts ? They are both safe on plastics.

I'm not familiar with Tronic Kleen.  But, it sounds like it is OK.
  Lot's of different TV tuner spays. Again, the "safe for plastics" is important.

[BobbyR]

I must say this is the type thread is what separates this forum from most others. An expert took their time to show how this is properly done, clearly explained and with photographs. This knowledge should put in a easily accessible place.  Kudos to Lloyd for taking the time to to this.

[Picasoo]

I must say this is the type thread is what separates this forum from most others. An expert took their time to show how this is properly done, clearly explained and with photographs. This knowledge should put in a easily accessible place.  Kudos to Lloyd for taking the time to to this.

Amen to that...!

[grcamna2]

How does viscous silicone differ from dielectric grease? is it much more liquid and less "grease"? I was told by a man in another forum that dielectric grease will keep my electrical grounds on my frame from making good contact & I need advice about what you think about the use of dielectric grease on for instance the coil bracket ground  connection to the bare frame.I never used viscous silicone before,but if I can get some I sure will start using it on switches & other electrical connections.
      Thank you for your help.

[TwoTired]

"Dielectric grease" is often a petroleum product, it is made by several manufacturers, and likely has several recipes for its manufacture.

Some greases will weep or liquefy and run, others will congeal and dry out, with varying time lines based on recipe used.  Petroleum based products also can break down and mix with or emulsify with water.

Silicone mixes with nothing.  It will shed water.  If it is viscous enough it won't wander away from where it is, even if heated. 

Dielectric grease is indeed an electrical insulator.  However, switch contacts have a wiping action the plows the grease away from the actual contact area.  Continued switch cycling will wear a nice clean path where that wiping action occurs.  Then the grease protect all the areas where wiping doesn't occur on component metals.  Note that the wiping action also mechanically removes surface oxidation, but only in the wiping contact path.

If you leave "ground contacts" loose, the grease will indeed insulate them.  However, a good mechanical metal to metal connection will squeeze grease out of the contact area and allow a good electrical connection that shouldn't corrode until the surrounding grease barrier is washed away or otherwise dislodged. 

The viscous silicone I used above is a little thicker than the viscosity of honey.  It will flow it excess quantity.  However it still leaves behind a thin surface film that sheds water and still keeps atmospheric contaminants and oxygen away from the metal that will, if left exposed, corrode.

Hope this helps,

[grcamna2]

That all sure does help...where can I get that viscous silicone ? is it avail. in selected stores or anywhere ?

[FuZZie]

Look for "100% dielectric silicone compound" , it's available at most automotive jobbers. The one I use part number is # 30-ds80 and is a 80ml tube witch should last you a long time. I think my cost was like 6 bucks. It's used to protect GM EFI module's and all sockets and connectors.

Note:
I've not used this on the switches TwoTired is rebuilding here but it should work well. Maybe if you have a chance TwoTired you could check this stuff out it could be a good easy source for the guys needing this stuff.

[apehanger 550]

  I wonder if the silicone grease that plumbers use inside faucets and such is the same stuff. It is marked as 100% silicone and is good for faucet assemblies and such. The advantage is a much lower cost.
  Many products have multiple applications,and I wonder if this is one of them?