(Topic ID: 172688)

Gottlieb Volcano coil question

By MostlyHrmlss

5 years ago

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  • Latest reply 5 years ago by MostlyHrmlss
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#1 5 years ago

The subway kicker doesn't seem to be as strong as it should be, i.e. sometimes the ball just drops right down the drain instead of hitting the right flipper as it should. The mechanism moves freely, the core moves through the coil smoothly. The manual describes how to aim the ball guides, but that doesn't provide much movement and didn't help anyway.

The coil that is on it is an aftermarket A-1496 (same as the slingshots, kicking rubber, and pop bumpers); being aftermarket it has obviously been replaced. I can't find mention of the specific coil in the manual, only a generic listing of common coils that doesn't mention the subway kicker and a somewhat less than helpful note saying coils vary from game to game and that I should consult the manual.

Could someone take a look in their Volcano and tell me what coil you have in there, and if it looks original? Is there a way to give it a boost, say with a capacitor or a stronger coil?

#2 5 years ago

Think you have the wrong coil installed. Mine has an A-5194 and ball goes to right flipper everytime

Hope that helps.

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#3 5 years ago

There should be a coil chart in the manual that lists all the coil locations and part numbers for the coils. I remember seeing it in the volcano manual specifically.

#4 5 years ago

I don't have a Volcano manual, but that is what is installed in my machine.

The coil charts can get confusing if not 100% sure if someone replaced with the wrong one.

Looking at my Haunted House coil chart it states:

Kicking target A-1496 & A-5195
Pop bumpers A-1496 & A-4893
Ball Kicker A-4893 & A-19300

I can see how one can get confused.

#5 5 years ago

If it's just a little weak and you have the wrong one you could mod that one by measuring resistance and then removing windings. Say it is 5.4 ohms remove windings till 5.2 can make a big difference. You can adjust to exactly what you like and get an education experience at same time.

#6 5 years ago

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#7 5 years ago

OzPaul: Great pictures, thanks for that. Unfortunately since that coil is also aftermarket, I have to wonder if it is the right one. You hit the nail on the head regarding the chart: it's not terribly helpful, showing coils for features I don't have, multiple coils for features I do have, and no listing for the one I'm looking for.

Here's hoping another Volcano owner will chime in.

#8 5 years ago

The A-4893 solenoid is the strongest one listed and will work fine, it's probably what belongs there. The playfield wiring schematic in the manual will list which solenoid was used.

If you want to get fancy, you can use a super flipper solenoid since it's a little stronger than the A-4893. Then you can add an EOS switch to make the power adjustable. If the switch is adjusted to open early, you get a weaker kick from the solenoid, if the switch opens late, a stronger kick.

I like doing this type of mod whenever I can because it gives me less wear and tear on hard to find parts, basically anything plastic that can break from the ball hitting it as it gets fired back onto the playfield. It also helps save the solenoid from burning up if the 5VDC or ground is lost at the driver board if you're running original boards in the game.

Steve (posting again from the hospital)
System 80, not just a job, it's an adventure

#9 5 years ago

Steve, you're a genius: I spent another hour staring at the schematics and found a little chart down in the corner listing the coils. Lo and behold, it is supposed to be an A-4893. Thanks for the tip!

#10 5 years ago

So, I got the right coil (ordered on Friday, it came on Monday; the guys at PBResource are great!) and put it in, the kicker didn't work. It would fire when grounding the case of the associated transistor on the driver board, so I figured that transistor was marginal and blew under the higher current. I pulled out the old transistor and it tested good with a meter, so I put it back in. The coil still didn't fire in play, so I went to test it by grounding the case and all of the coils would fire (all of the coils fired by UPTs, not the direct ones fired by big transistors on the driver board), just like the 'thunk' sound when turning on the power.

Not knowing what the hell to think about that, I replaced the transistor with a new one. Now the coil still does not fire in play, but the transistor gets hot, I mean makes-a-funny-smell-and-you-can't-touch-it hot. The other two big transistors do not. The coil still fires when the case is grounded (and only that coil), so it's not stuck on. It would also fire when I put 5V on the base leg, so I replaced the upstream transistor too, but nothing changed. The only thing out of place is that this transistor did not have the mica gasket under it, but the solder pads around the holes on the component side of the board did not look big enough to contact the case and the last one worked fine without it.

Any ideas?

#11 5 years ago

I'd suspect the IC driving the transistor next. Although the transistor heating up like that sounds odd. Are you sure it isn't backwards?

#12 5 years ago

If the IC were driving it constantly the coil would be locked on. It can't be backwards, the pins are closer to one mounting screw.

I suppose I could make sure the pin pads aren't touching the case with some electrical tape or by floating the whole thing off the board with some washers, but I wasn't sure if either of those would be copacetic. Besides, one of the pins (emitter) goes to ground (which would make the coil lock on if it were making contact) and the other (base) is fed by the upstream transistor and a 9.1Ω 1W pull-up resistor, and I don't think either could feed it enough current to make it heat up as fast as it does. I could be wrong, though.

#13 5 years ago

Can you post a couple photos?

Quoted from MostlyHrmlss:

with some washers

Keep in mind, metal washers are electrically conductive.

Quoted from MostlyHrmlss:

I don't think either could feed it enough current to make it heat up as fast as it does. I could be wrong, though.

Too much current or voltage in the wrong direction can easily cook things.

#14 5 years ago

i would think it is supposed to have a Mica under it.

#15 5 years ago

Yeah, metal washers around the mounting screws between the transistor case and the component side of the board, just to lift it up a bit to keep the pins from hitting the pads on the component side of the board. I can't imagine why the pads are there at all, the pins are connected on the solder side. The circuit relies on a good connection between the case and the board, so any standoff would best be conductive, especially if you trim the mica as suggested in Clay's guide. Instead of doing that I ended up making my own insulator out of some plastic I had lying around, I made sure it wouldn't melt by hitting it with a heat gun on high.

Today I pulled the new transistor (the one that gets hot) and it tested bad with the meter. I didn't test it before I put it in, so I have no way to know if it was DOA or it burnt out after installation. Does anybody test new components before installation? I might do that from now on...

I put the old transistor back in (it was still testing good), and it went back to firing all of coils at once when grounded. I then pulled the transistor out, reinstalled the board and grounded the pad where the case contacts the board. It was then that I noticed that it wasn't just the other coils firing, it was every durn controlled light on the board! Turns out the new coil reads about 0.6 Ω, so I put the A-1496 back in and everything's back the way it was in the first place. I still haven't figured out how a shorted coil could make other transistors fire.

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