Need Pinball Repair Help!!! I Think I Fried a coil?

[PCtech]

OK, I just realized this is the first time I've asked for tech help....shows how desperate I am.

In a nutshell...I have a 1976 Sonic (Segasa) Mars Trek Pinball, with a burnt out Flipper coil (solenoid...sp?).

Pinball was working fine when I got it (right lower flipper was a little weak), played it for a couple weeks, Then I get lights, but that's it, no sounds, no action at all, just lights.  Then, the burning smell set in (being in electronics, I know, and dread that smell). 

I pop the hood, and notice that one of my coils is a lot more "black" then the others, and also find out that it is the source of the smell...I'm thinking "ok, I burnt out a coil"...no big deal.  Just for fun, I take the flipper coil from the upper right flipper (not used as much as the others), and install it where the burnt one is.  Did not work.

My questions:

1) What are the chances that I just burned out the coil, and nothing else?
2) For those of you with experience, are coil burnouts that common, and do they normally take other things with them?
3) Can the machine still run (normally) with one coil removed (contunity paths, etc)

I know these are kinda generic questions, and I think I have spare parts lined up, just wondering how bad this could be (for those that have run into it before)

The reason it is so urgent .....this is the first pinball I really got into (when I was about 7-8).  My dad used to take me to this old arcade, and he and I would play this machine for hours.

Well, I've been trying to find one for literally 11 years.  I found one, but didn't get a chance to pick it up before it got sold.  I got lucky on this one.  A church in Chicago, wanted to get rid of it because it didn't work (one of the rubbers broke, and the ball was stuck in the playfield.  I offered them $100 for it (I still feel slightly guilty), and they jumped at the chance to get rid of it.  I've had it since Christmas last year, but due to problems at home over the summer it got "back-burnered"

Well..my Dad's 60th birthday is on October 23rd, and I sooooo want to give this to him on that day.   He know I'm into vids, but he has no idea about this.....and other than the damn flipper coil, it was working fine.

Any ideas Would be so appreciated.....thanks!

[Buddabing]

First off, check out the repair guides at http://www.marvin3m.com.

It's possible that it's just a coil. Are there fuses on the flipper coils? If so, swap the good fuse from your working flipper, that may be what is wrong. If not, there probably should be.

When you order your new coil, order some coil sleeves while you're at it.

[PCtech]

Thanks for the advice   

I don't think they have fuses (at least I didn't notice any), and being 30 years old it would suprise me.

I let you know how it goes.

[D_Zoot]

Wow, a Sonic?   I personally just don't see any of those around!

I can't be very specific, because I have never had the fortune to work on a Sonic and I don't know how they generally do things,  but:

On Electo Mechanical (or EM) machines, which that one is, power is often daisy chained from one relay or solenoid to another.   If you cut the wiring off a component, such as a flipper coil,  you can sometimes interrupt power to other parts of the chain.   Look at your coil wiring, if there are two or more wires on a single lug then this might be the case.   The tricky bit in figuring this out is the end of stroke switch.  One of the lugs on the flipper coil probably has two wires on it, one wire going right over to the EOS switch on the flipper, don't count that one if you are looking at it to determine if power is daisy chained.

There will be fuses somewhere in the cab,  EM's were usually in the bottom of the cab more toward the front.  But I'm not familiar with that machine, so they could be anywhere.  Find them and check them all with a meter.  Don't rely on a visual inspection because sometimes fuses will look ok but can still be blown (slow-blo fuses in particular can be hard to tell sometimes).


If your flipper coil is indeed burnt, then have a close look at the EOS switch on the flipper.  If it's sticking, has improper clearance or not breaking contact when the flipper is at full travel that can cause your coil to overheat since the pull-in winding will remain on when it shouldn't.


Now, a bad flipper coil and/or EOS switch shouldn't cause the game to not work (unless it blew a fuse) and a flipper problem usually won't cause the flipper coil to burn and smell hot when the game is idle.   I almost thing you have a problem somewhere else in the game.  A stuck contact keeping a tilt, game over, hold, reset or some other relay energized when it shouldn't be.  Look carefully at all the relay banks for problems there.

Good luck!
D

[fredster]

And make sure you replace that diode in circuit.  If that diode is fried it can cause all kinds of problems with the feedback voltage.

[ChadTower]

Do the solenoids in an EM have diodes?

[fredster]

I have had one EM and one SS.I had one that did. But it had some major modifications to the electrical system in it.  All the SS ones did to prevent feedback.

[D_Zoot]

Do the solenoids in an EM have diodes?

No.  Diodes in SS machines are to prevent voltage spikes (inductive pulse generated by the coil into itself as the magnetic field collapses when the coil is turned off) from reaching the electronics and damagine solid state components.   Diodes aren't needed on an EM machines.  Besides,  EM machines generally used AC voltage for the flippers, a diode would burn open in a fraction of a second wired across AC.


D

[PCtech]

Hate to resurrect this, but finally getting around to some good suggestions....

Last past was regarding diodes on the coils, and how EM machines don't use/need them. 

I replaced the flipper coil that burnt out in my 1976 Mars Trek (Sonic/Segasa), and I'm popping fuses like popcorn.  Everything on the game appears to work beautifully, until I press the right flipper button.  Instead of energizing the flippers, it blows a fuse.  I also notice that a couple playfield lights light up, right before the fuse goes POP.  I've checked my wiring, everything looks good.  Also, left flippers work great!

Could it be the diode on the coil that is the problem.  I got the exact same part# from Marco, but I noticed the new one had a diode, and thought "maybey someone improved on it in the last 30 years"...now I'm thinking that it's only for newer machines that mine (mine has no circuits in it at all....all EM).

Thank for any advice.....I just missed father's day with this one, but he was out of town for the last 2 weeks, and hope to get it to him this weekend.

[Ken Layton]

We used to have a couple of these Mars Trek games on our route years ago. I remember liking them as they were fun to play. It's internal parts are for the most part Williams electromechanical parts.

This game had DC powered flippers and jet bumpers. There's a bridge rectifier mounted under the playfield. Chances are it's ok since your other flipper works.

On this game the lower right flipper operates TWO end-of-stroke switches. When the lower right flipper pulls in, one set of switches opens which breaks the high power 'pull-in' coil winding preventing the flipper from burning up. The other switch closes to provide power to the upper right flipper coil (which only has a single end-of-stroke switch on it).

Be sure the flipper pawl (knuckle) has a piece of heat shrink tubing on the piece that actually contacts the end-of-stroke blade. It must be insulated or you'll blow the fuse when the flipper is actuated.

Always double-check the wiring to the flipper coils to be sure you don't have the end-of-stroke switch wired to the wrong coil terminals. If the replacement coil has diodes on it, remove them as they are not used in electromechanical pinball machines.

[PCtech]

Ken - Thanks so much for the advice, I'll be looking at what you suggested tomorrow morning.  The quick help was great, and knowing the rep you have for the electrical stuff, it is much appreciated!

 

[PCtech]

If the replacement coil has diodes on it, remove them as they are not used in electromechanical pinball machines.
 

That was it!

I snapped off that diode, and both right-side flippers started working
Other than a little "jitter" from the bottom right flipper when it's full stroke, the flippers work great.

I was waiting to give it a good cleaning, before giving to my Dad.  Now I figure I have about 3-4 hours of cleaning, waxing, polishing, and minor adjustment.

Ken...I can't tell you how much this means to me.  That was the last peice of the puzzle, for a dream I've had for almost 20 years...to restore the old pinball my dad and I used to spend hours playing, when I was about 8-10 years old.

Now, all I have to do is find a couple folks to help me move this monster...but that's no sweat.

Thanks to everyone who helped make this possible for me!!!!!

[Ken Layton]

The "jitter" is usually caused by a worn flipper plunger & link assembly along with the coil stop bracket. Replacing those usually will fix that.

[vintagegamer]

You are very lucky to have had a dad who liked to do those sorts of things with you- that's what I'm hoping to do w/my daughter..  Enjoy.

VINTAGEGAMER