(Topic ID: 142632)

contact point question...

By Foose

6 years ago


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  • 14 posts
  • 8 Pinsiders participating
  • Latest reply 6 years ago by Foose
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#1 6 years ago

Hi everyone,

im new to pinside, and infact new to the pinball addiction in general, so ill apologize in advance if my questions seem obvious to the hardened pin-veteran.

im currently working on restoring my second EM machine... the first was a 1975 gottlieb abra cadabra which is now pretty much working awesome, the second machine that is still in-process is a 1967 williams derby day. my question is actually about the fat blue spark you typically see on most of the contact points when they are actuated....you see, i come from a vintage motorcycle restoration background, so when i see a fat spark jumping across contact points like that, my immediate reaction is to get a new condenser (capacitor) and put it across the points to soak up that extra voltage, thereby decreasing the spark that jumps the gap and prolonging the life of the points....well, i notice that in both my EM machines they use no caps or condensers on any of the points.....so my question is basically if the sparks im seeing are absolutely normal, and shouldnt be bothered with, or if theyre indicative of dirty contact points (which im sure they all are) or if adding capacitors to the points was simply viewed as unnecessary and/or too costly to bother with during the era of manufacture? im never a big fan of modifying original equipment, but if adding capacitors across the points will prolong the life of the points while not adversely affecting gameplay, i might be persuaded to do it.

again, im still learning the lay of the land with these machines, so bear with me as i cut my teeth, and thanks for your help!

Foose

ps you might notice in the picture that the derby day has an incorrect backglass, hayburners 2, which was released the year after derby day....im not sure if this was a hodge-podge machine from the factory, or if it was a repair made after the fact and the hayburners glass was all that was available....its been a very interesting machine to work on so far.

IMG_20151014_211402460.jpg

#2 6 years ago

New points, condensor, and a few adjustments and y'all should be havin' her runnin' like new agin.

#3 6 years ago

i was asking a serious question. is that a serious answer? because it sounds like its not. but then theres a lot of inflection lost through text.

#4 6 years ago
Quoted from Foose:

is that a serious answer

No, it would of been a Funny answer that required a or a . I do not speak for O-Din. But zingers are his specialty.

#5 6 years ago
Quoted from Foose:

i see a fat spark

blue sparks are fairly common in EM's

http://www.pinrepair.com/em/index3.htm

#6 6 years ago

No condensors or contact cleaner please. Usually all that is required is a good cleaning. A flex stone will work for most, a point file does the trick on the tungsten contacts. A blue spark is normal but if it's excessive it could be a sign of dirty contacts or another issue.

That Hayburners glass looks very appropriate in the machine. If you hadn't mentioned it I wouldn't have noticed it being out of place.

#7 6 years ago

Just burnish the contacts with a flexstone or hard file (for the larger size ones). No caps added or needed.

#8 6 years ago

Thanks everyone for the help...like I said I'm generally against modifying an original design, though I'm usually looking for ways to improve things too. Which leads me to my next question....while replacing the crispy flipper coils I noticed some of the bake light parts were very worn....so, being a machinist, I went downstairs and milled out some fancy new aluminum ones, pictured here....and they work great. Except now I've got this nagging question of whether or not aluminum was the best way to go....why did they use that bake light/phenolic material? Have I done my machine a disservice? I added those little cutouts on the sides to reduce the weight of them, figuring that would be the main difference between the aluminum and the bake light...thoughts?IMG_20151019_225201427.jpg

#9 6 years ago

I wondered the exact same thing. Why phenolic?

#10 6 years ago

it's cheap, sturdy, and doesn't conduct.

#11 6 years ago

The conductivity thing had occurred to me, but I figured the only time that would be a problem is if the steel center rubbed through the nylon sleeve, and a few winds of coil as well, and then shorted out, and even in this case I think it would burn out the coil before your flipper linkage got hot enough to do much damage. I mean I'm hoping so, anyway!

#12 6 years ago

The earlier games had metal flipper links with brass coil sleeves.

#13 6 years ago

Nice work on the Links!

You may find in time, that the holes will elongate on them. Which, as that happens may cause them to bind and not flop around freely like they should.

Just so you know, after years and years of using Phenolic for links, the industry went to thermoplastics since the Phenolic did not hold up very well with the newer, stronger flippers (later 80's). The plastic tended, not to elongate but unfortunately, to break. People tried various alternatives including various metals. But while the metals tended to be stronger, they certainly opened up the holes much faster. So, they returned to what must have been a better mix of thermoplastic since it is still in use today. And typically, the other parts around the plastic wear before the plastic does.

#14 6 years ago

Thanks! I had also thought they might have avoided aluminum because it might tend to dent and deform faster, and the phenolic would sort of bounce back after every hit and only become elongated over time...I suppose this machine will be the acid test on that one, but don't worry....I've become an unrepentant hoarder, so I saved all the originals.

I also have a little bit of this fancy composite called G10....its some kind of crazy fiberglass type of stuff, but it absolutely destroys carbide end mills when you cut it. I was going to try it but I only had enough material for 3 links and if I was going to change them, they were all going to be identical.

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