Ball eject coil on Xenon

[kevin]

When I started a game, the coil started smoking. I took it apart and see that the plastic inside the coil is melted and warped, preventing the plunger from getting through. The coil that was in there says Gottlieb on it and didn't quite fit in there very well (it's a little too small). Could this be why the thing overheated? There is also some pretty shitty-looking soldering that was done on this machine, but it looks like the two wires going into this coil are soldered fine.

The guy told me he was blowing fuses by using the left flipper. I noticed that one of the wires going to the EOS is not even soldered (it's just hooked into the little hole). Seems like that was the problem.

Is anyone planning on ordering some parts and want to split shipping?

[Opto]

Sorry Kevin - just place one. However, since you probably need a rubber kit, and flipper rebuild kit in addition to that coil, you could (and probably should seeing as though you own 3 machines now), start an account with pinball resource. It's pretty easy actually and I've been emailing my orders in to avoid getting the comic book guy treatment from Steve. You need to order $50 worth of parts on your first order with them to start an account (a flipper kit/rubber kit + coil should get you there - you can always add things like new leg levelers/bolts, new pinball etc). They give you the total - you mail them a check, the ship the parts when they receive the check. Any orders down the road, you simply email/call them with what you want and then send it with an invoice that you have to pay (by check) within 10 business days or so. Shipping really sucks when you're ordering one or two parts, but if you get a flip kit, and rubber kit, the shipping/product cost ratio gets a lot better - probably less the $8 for what you need.

Just make sure you include the part number of the coil you need - you can find it in the manual. Also they have part numbers for their flipper rebuild kits. Rubber kits, you just need to specify the game, color of rings (white or black) and color of flip rubber (red, yellow or black). You can always see what color of flipper rubber a game is supposed to have by looking up the flyer online. Most classic SS Bally games shipped with yellow rubber - I put red on my williams games.

Anyway - here's the email address/phone number

pbr@pbresource.com
845-473-7114

[eric]

Before you do anything else, go through every fuse in the game and verify the correct values are installed. F4 probably should have blown before your coil melted. It's likely over fused. This should always be done BEFORE you start working on an unknown game.

Definitely replace the melted GTB coil with a Bally AO-27-1300. Also check the driving transistor on the solenoid driver board as it could be bad. Do you own a DMM?

Re: EOS, re-solder it and verify it opens far enough when the flipper is engaged.

[revtest]

placing an order with PBR today if you want in on it! i'll txt you also case you don't see this till later!

[kevin]

Does anyone have a suggestion on where to buy a DMM? I saw a couple at Radio Shack, but maybe there is somewhere with better selection.

[Opto]

I bought my fluke IV on Ebay for used for $80 - it seemed like a lot at the time, but it's very easy to use (auto ranging) and it does everything you need it to do. I think a fluke III will work fine as well, but check with Eric. Used on ebay seems to be the way to go.

[eric]

The meters at RadioShack will work but are cheap and break easily. I bought a new-ish Fluke 77 on eBay three years ago for about $75 and have been extremely happy with it. IMO it's definitely worth the extra money for a more robust meter. Whatever you buy make sure it can test AC and DC voltage, resistance, continuity, and has a diode test. Auto ranging or manual ranging is less important. Auto is really convenient, but can be limiting at times. The 77 is nice because it can be set to either auto or manual ranging.

Also pickup a few electronics books from the library. Clay's site is thorough enough that you can totally fake your way through most repairs (i.e. put red lead here, black lead here) but it helps immensely to have a basic understanding of the physics behind it. This will also help you from making stupid mistakes that could potentially damage your machine or hurt yourself.

[kevin]

I did a diode test on the diode that is on the overheated, melted coil. The diode is no good. I wonder if this was the cause of the overheating, or an effect of the overheating.

[eric]

Probably, but in an indirect way. The diode prevents the back EMF created by the collapsing electromagnetic field from damaging the coil's driving transistor. Bad coil diode means your driving transistor is probably shorted which would cause your coil to lock on and eventually melt.

[ROM]

[kevin]

I checked all the transistors on the solenoid driver board. They were all fine until I got to the last one, Q19, which was missing entirely. It is listed in the schematics, so it's not supposed to be empty. Could a missing transistor cause the problems of the left flipper blowing the fuse or the ball eject coil melting?

Part of the problem with the ball eject coil overheating may have been due to the guy who had the machine before putting a slow blow fuse in F4 instead of a fast acting (as called for by the manual). I guess you can't trust anything done to a machine by the previous owner.

[eric]

The missing transistor would not have caused your eject coil to melt. Q19 drives the lockout relay so I'm guessing they pulled it to keep the relay from buzzing in the coin door (though simply clipping a wire from one of its lugs would have been a far less invasive way of accomplishing the same thing). The top saucer is driven by Q17. If Q17 tested good then just replace the coil and coil diode (new coil should already have a diode installed) and see if this resolves the problem. Take note of how the wires are soldered in relation to coil diode. Solder power lead(s) to the lug connected to the banded side of the diode, ground lead to the non-banded side.

Regarding the flipper blowing a fuse:
-Make sure the end of stroke switch is opening when the flipper is actuated.
-Test the flipper coil diodes.
-Check to make sure the coil resistance is good. Flipper coils are two concentrically wound coils in one housing wired in parallel or series. To check resistance first make sure the power is off. Put a business card or something else non-conductive in the EOS to keep it open while you're testing. Find the lug that has both a thick and thin wire going to it. This is the common lug. Find the lug that has only a think wire going to it. Measure resistance across these two lugs. You should see between 2.5 to 5 ohms. This is the resistance of the high power side of the coil, the one that powers the bat during the flip but is shorted out when the EOS opens to keep the coil from over heating. Next, find the lug that has only a skinny wire going to it. Measure resistance across this lug and the common lug. You should see somewhere between 100-300 ohms. This is the resistance of the hold side of the coil and keeps the bat held upright when you hold the button in.

Let us know what you find!

[eric]

Kevin and I went through his Xenon last night. High power side of left flipper coil was shorted (0.5 ohms) and the driving transistor for the kickout was bad.

[Opto]

Hey kevin - if you're gonna order a new coil, I've got some stuff I need too - we could split shipping?