what are switch contacts made of????

[bob in phx]

Ive been cleaning the switches on my bally 873 5 line em slot. I use an antique at+t contact cleaning tool (flex stone???) While I was cleaning, I noticed that the contact on one of the switches was really really shinny. It looked like brass!!! all the rest of the contacts were black. I guess I always thought that these contacts were tungstun or something.. are they all brass?????????

[brichter]

Depending on the year of manufacture (I've only fixed one Bally EM in my slot life) it probably could be brass, I'd imagine the later models would be plated with nickel or some such to increase the contact life.

I'm glad I'm not the only one old enough to know how to file contacts...

[bob in phx]

Its really not filing the contacts is Burnishing... or so I was told by some old guy, nearly 40 years ago!!!! the burnishing tool I am using is most likely older then I am... The next thing is to adjust the contact so that they are open when the should be and when they are closed, they provide some wiping action... At my age, making that adjustment requires MAGNIFICATION!!!! at my age!!
Thanks for the reply and the smile that the "old" comment gave me...
bob in phx

[brichter]

If they are brass, just use a little ammonia on a matchbook cover to get rid of the funk. It'll dissolve the crap without taking away any metal. The contact tool will actually file down the brass because it's so soft. The tool has a very fine grit, but it is a grit that will remove metal. It was designed for use on harder metal contacts like the nickel plated ones.

[bob in phx]

ill give it a try!!!!!!!!!

bob

[StatFreak]

Woa there! I strongly recommend waiting until either Foxsslots or Op-Bell responds before putting any cleaning agent on those contacts!

Here is an excerpt from the manual:

Switch contacts must never be filed as this destroys the seat, and in so doing, causes further arcing which eventually burns out the contact. Especially never file the dome shape contact as this is specifically shaped to burn a good seat in the flat contact. This in turn keeps the seat clean.

Should cleaning be necessary, use crocus cloth or some other very fine abrasive surface rubbed between both surfaces, as usually some foreign matter has lodged between the contacts.

Carbon need not be removed between contacts as this is a good conductor and prevents oxidation of the silver contacts.

[brichter]

If they are brass, just use a little ammonia on a matchbook cover to get rid of the funk.

Please note, my statement was made specifically in regards to brass contacts.

[Op-Bell]

I did start to reply last night, but canned it because I wasn't sure. I checked up since. The original leaf spring contacts are silver, which goes black with silver sulfide. The sulfide is quite soft and wears through constantly in normal use - it only becomes a problem if the machine is left sitting for months (less if you live near a hot spring or coal-fired power station). I clean them up with a piece of thin card sprayed with WD-40, and rubbed between the closed contacts. It shouldn't take more than that. If you have a shiny brass contact it's probably been replaced in the life of the machine, and it's more likely to be gold than brass. If it's gold it will be very thin plating, and you'll wear through it with a couple of swipes if you use anything abrasive.

[bob in phx]

all cleaned and adjusted. Burnishing tool did the trick. Now, some of you are saying that ruined the switch stacks, but I have to tell you that before I got this machine, I saw the original owner going at the stacks with a sandpaper nail file. I took one of the small low voltage contact leaves out and they are not brass, they are not silver, they are not gold, They appear to be black anodized steel. I took the point/contact out of the leaf and it was magnetic, thus, I beleive that they are steel and anodized or some other treatment to keep them from rusting... thats my emperical viewpoint!!!!

bob in phx...

[litterbox99]

FWIW: I was told by an old operator/friend from the 70's & 80's (RIP as he's passed) never to use a file, just an un-coated business card
or thick card stock w/texture and some cleaning solvent.  I gotta admit, I've used a fine file to do this, but just enough to take off the
gunk.  Just remember, every time this contact makes or breaks (depending on the current going into the switch) there's a chemical reaction
that leaves residue or carbon.  I've often wondered, on the em-slots, if you lubed the brass nubs on the reader PCB with dielectric grease if it would help.

Doing this may cut down on the residue and since it's a lube, it would help things move smoother.  On my buddies em slot, we cleaned the
contacts and then wiped the reader PCB contacts with a bit of hi-tech lube and a rag.  It helped quite a bit.  Did the same with the
step up unit and it helped it snap back into place.

[PWRSTROKE]

fwiw, The dielectric "grease" will work. I have seen its use in over hundreds of diff. applications such as this one-from big industry to small.  It is heavly used in the auto-manufactures componets -and for a reason.  I have the mdss on this product and it may feel and look like grease but it is not.  This is why we can use it with electronic/voltage/heat componets.  -Good stuff in my opinion for the application-Use in moderation.  B.

[FOXSSLOTS1]

 to clean contact points use a BURNISHING TOOL which is nothing more than a flat piece of metal or a flat edge razor blade -  place the tool or the razor between the 2 parts of the contact switch - squeeze the switch against the blade and move the blade/tool back and forth - thats how you clean the contacts - NEVER use any abrasive - once you do - kiss the contact goodbye.  There are contact cleaners but I never had much luck with them