I’m working on a Gottlieb Atlantis. It’s an EM, but what I’m trying to do is more in the realm of an SS technician’s expertise, so I figured this would be a good forum for my question.

The coin lockout coil on Gottlieb EMs is nearly continuous duty. It only turns off when the score motor is turning. Because it’s on for such long periods of time, it gets very toasty. The crispy brown spot on the underneath of the lower end of the playfield is the long-term result of this heat. At this advanced age in these games’ life, the mechanism does not perform well. It usually makes a racket—vibrating like hell from metal fatigue and other factors—and most mechanical adjustments do little to dampen the noise.

So I picked up a 220-ohm A-16890 coil from PBR and want to correctly half-wave rectify it, making the coin lockout mechanism reliably functional and quiet. I’m following the instructions Clay Harrell wrote on Pinrepair.com for fixing tired Hold and Game Over relays. I was able to use two IN4004 diodes to get the half-wave rectification, but the ripple is bad and the coil struggles to pull in the actuating plate. Clay’s instructions mention that Gottlieb often used a capacitor and resistor to smoothen the ripple.

Schematic

So I picked up a couple of capacitors and resistors from Mouser. Here is the part number, description, and photo of the capacitor:

Aluminum Electrolytic Capacitors - Axial Leaded Aluminum Electrolytic Capacitors - Axial Leaded 50uF 50V Custom P/N

Capacitor

Here is the same info for the resistor:

WSC00026R000FEB Wirewound Resistors - SMD Wirewound Resistors - SMD 2watts 6ohms 1%

Resistor

Then here is how my coin lockout mechanism is currently wired with the diodes and A-16890:

Coin Lockout Mechanism

Can an expert in here advise me how I can marry the capacitor, resistor, diodes, and coil? Also, do I have the right capacitor and resistor?

Thanks very much.

I used to just disconnect the noisy ones, but lately I’ve been making an effort to get my restored games fully coin-operable, including the coin lockout. Whatever the reason, I find it very satisfying. Just strolling through my game room with everything off, I’ll drop a random quarter just to hear it clatter into the coin return.

Incidentally, I tried to use just a capacitor to smoothen the ripple. It worked for about five minutes, then the capacitor burst and gassed out. I’m guessing the resistor is necessary. And maybe I need more than the 6-watt, 2-ohm resistor that I bought. Line voltage is higher than it was 40 years ago, so the 24-VAC circuit is actually measuring at nearly 30 VAC. Thoughts on the resistor?

Anyhow, just looking for some expert guidance. I’d like to learn more about DC power; this has been a fun exercise.

Thanks for the links. I do like how unobtrusive the bridge rectifier would look.

Because the coil turns off every time the motor turns, does the bridge rectifier need a diode to protect it from backwards voltage surge?

I think I had it right. The longer lead off the end with the CDE arrow (I think that is cathode) was connected to the same lug as the banded diode.

Was that right?

Thanks. You’re confirming what I just read in the technical specification PDF for this capacitor. Man, how hard is it for them to just print a minus or negative sign on the dang thing itself?!

Capacitor Specs

I appreciate @GRUMPY’s advice on using a bridge rectifier, and I’ll try it next time I do this. For this Atlantis, however, I’d like to try utilizing the parts I have on hand. This drawing is how I intend to wire them together. Does it look correct according to the schematic?

Proposed Wiring

Gottlieb Schematic

It’s not pretty, but it works. I left it energized for a long time and there’s no heat on the coil or capacitor.

IMG_8386 (resized).JPG

Next time I’ll do the bridge.

Thanks for the counsel, y’all.

What is the name for that thing? Some kind of mounting board would be great for securing and compartmentalizing all these little components.

I wish I could find one. Mouser has exactly one (!) stocked option for this rating of resistor. Is there another source I should consider?

Thanks for the feedback. I don’t mind the criticism. I gave the resistor/diode choo-choo train a couple of rude yanks and it doesn’t yield. This stuff is on the coin door, where it’s pretty sleepy. Maybe if I put the game on location and have delinquents banging on the coin door!

On EMs, that diode lengthens the life of the bridge rectifier.

I bought a pack of these and will use it to stabilize everything.

412mn+246mL._AC_ (resized).jpg

Then NEXT time I will just use a bridge rectifier.

When I first got into pinball ten years ago, I kept cooking transistors on the driver board for a System 1 game. I swore off SS games and stayed with EMs. This has been a good learning experience.

I’m in no hurry. I’ll PM my address to you. Thanks!