Installing a knocker in Stern’s World Poker Tour pinball

I just installed a knocker in my World Poker Tour. I used Stern’s step-up board, the one that is used for the kickout from the bumpers, available from the usual suspects. I got most of my information from this page.

A few random notes:

I used a 520-5254-00, available from Pinball Life, and documented in the WPT manual.  Because the knocker drive transistor can only sink 20V, a step-up board is required.

Three connections to the game are required: +50V, solenoid ground, and signal. Okay, you could probably use +20V if you wanted a wimpy knock from a wimpy coil. You can source the signal from the connector under the playfield that is used to drive the coin counter that nobody installs. +50V and solenoid ground can be found on J10. On WPT, it appears that pin 8 is not used, but it is fused by F7. Great deal! Three pins on J10 offer solenoid ground.  I used pin 2, but 4 and 5 would have worked. (You can pick up ground anywhere, but it is probably better to pick up the officially blessed solenoid ground.)  I happen to have an IDC punch-down tool.  I’ve had it for fourteen years, and now I’ve used it.  I didn’t have to solder anything (other than the coil) because I picked up all of the connections from connectors that already existed, which makes for a nice clean install.

I installed a Williams knocker, in the head. Mine was apparently from a High Speed, but it’s the same mechanism Williams used until they gave up on knockers.  The geometry of the Stern head leaves a lot to be desired from a knocker perspective. I will probably install the next knocker in the cabinet, and even that can be trying as I have discovered previously.

I put the head in the upper-right mounted to the side of the cabinet.  This was a tight squeeze for the assembly, and it was hard to install and it will be hard to remove for service.  I mounted the knocker on a block of scrap wood, then screwed that to the cabinet.  I don’t like the adapter block, but because of the diagonal brace in the corners of the head, a the knocker wouldn’t have clearance if it screwed to the head directly, and there’s no room for it on the back of the head.

I set the Q24 option to “knocker” and the “knocker volume” to off.  I discovered the “knocker” test drives both the real knocker and the fake knocker and it’s loud as hell. There is no other test for Q24.

Next time I install one of these, should I ever get another Stern game, I’ll probably try the Gottlieb knocker.  It doesn’t require a separate strike plate.  Running on +50V, it’s probably not as anemic as in a Gottlieb game. Or, perhaps I’ll mount a Data East-style unit in the head, down below the computers, where there’s space.

A modern Williams knocker fires up and has no spring.  Bally, Data East/Sega, and old Stern Electronics knockers fire at the side of the cabinet.  The bracket used for Data East is the same as Williams, but the plunger is different.  Old Williams knockers, like on Firepower, and Gottlieb knockers fire at their own bracket, and are mounted in the cabinet. Stern Pinball has never used a knocker.

The sound of a Stern knocker is different than a Williams knocker.  It’s more of a thud than a crack.  I suspect the coil pulse is longer. I prefer the knocker on my Twilight Zone, but any mechanical knocker is better than the pop on a Stern game.

Adding a knocker to my Simpsons Pinball Party was similar, but I used a “Data East” knocker assembly (really, it appears to be a kickback assembly) and mounted it in the body. This gets even more of a “thud”, and it’s not nearly as loud, but not as satisfying.  Finding solenoid ground and +50V was more difficult and I did a bad job.  I should clean it up.


Update: there may be two versions of the 520-5254-00 board, one that takes a 20V input and one that doesn’t.  I haven’t used the 20V on yet, but that’s the one I want for future games. I asked about the difference to Stern’s technical support, and they responded:

The newer step up driver boards use 20V and 50V. The coil will fire using the 50V power. The 20V input is used to sense weather or not the voltage is present. This is important because if you have 50V without 20V, the coil will turn on until the fuse blows. I would recommend the new board!

I’m trying to confirm that the two boards have the same part number.  There are pictures of a five-pin version online with the same version number, but the parts sellers only picture the four-pin version.

With the four-pin version, sometimes my games knock on power-on, I assume due to the problem outlined above. (A little like the System 80 thunk, I’m sorry to say.)

a note about rebuilding Gottlieb “fat boy” flippers

In general, I don’t rebuild Gottlieb “fat boy” flippers as part of shopping out a game. This is in contrast to Williams solid-state flippers, which do wear out. The exception is the EOS switch. The lever arm will chew a hole in it over a couple decades of play, and it’s worth checking first. It may be fine, or it may need replacement.  I have also seen the plunger/link crack apart. But otherwise, these flippers just work.

On my Monte Carlo and couldn’t make the Firepower-esque lock shot, up the left side and into a saucer. Without this shot, there’s no multiball, and no way to spin the roulette wheel. The flippers seemed fine otherwise, but were clearly missing some oompf.

I replaced the sleeve because it’s cheap and checked out the link assembly, which seemed to be fine. I decided to get more drastic. I have a couple MA-989 upgrade kits with NOS link assemblies and new EOS switches that should make the EOS switch also nearly indestructible. I decided this was a fine occasion to use one. Ultimately, I replaced the EOS and lane change switches, the coil, the coil stop, the plunger/tip, and the lever that clamps around the flipper shaft. Still, it was weak, and in fact it was a little worse.

But in the process, I had installed the flipper with an angle that was too horizontal at rest. I think I was working off the angle of the left flipper, which wasn’t necessarily right to begin with.  I went back and took a look the flyer and went for a droopier angle, and happily, I can make the shot!

I suspect that flipper mechanism develops a lot of power at the end of its stroke.  Plus, the angle made the flipper play funny, and I may have had a hard time adjusting.

I will keep all the parts I took out as spares—I don’t think they’re bad. And I will pay more attention to the angle in the future.

I am not enamored with the MA-988/MA-989 upgrade kits. They require some care to ensure that the return spring isn’t touching the switch. The geometry of the flipper just doesn’t allow this fix to be very good. Plus, my NOS parts came with NOS factory rust in non-critical locations. The original flippers work pretty well without the fix.anyway. I will probably use these kits up and switch back to the original-issue parts once I exhaust my small supply.

Flash lamp weirdness

I chased down the flash lamp problems on my Monte Carlo.

The flash lamps next to the roulette wheel were locked on. I found a out-of-spec transistor on the driver board.  The under-playfield transistor (MJ2955) tested fine once the driver board was disconnected, so I just left it.

The other one was weirder. The “left dome” flashers did not work. Lamps themselves were fine. The transistors tested okay, and there was voltage at the lamp socket, but grounding the lamp socket did not cause the lamps to light.

I found that the two lugs of the lamp socket were shorted together. Apparently the resistor in circuit that steps down the voltage is good enough to protect the transistors from failing, or I just got lucky.

I might have caught this sooner if I’d noticed that the last person to re-rubber the game had looped rubber around 89 sockets rather than reading the manual for the correct rubber ring sizes.

My Monte Carlo

In March 2013, I picked up a Monte Carlo. Nominally, it was working. But it needs some work. Here’s a rundown so far.

The head glass was cracked in two pieces, held together by the trim — just barely. I got a new one through a friend who got it cheap, but we got it cut just a little too small.

Next, the mezzanine board on the MPU was cracked.  All System 80B games self destruct because of this damn board.  Because it is single-sided, and all single-sided boards on a pinball get cracked header pins, it causes the computer to become unreliable, if it boots at all.  Someone had “fixed” mine by jamming packing peanuts in it.  I fixed it by desoldering it, removing solder, adding fresh solder, and putting it back.

Fortunately, this game shipped with one of the cordless phone-style batteries and had not leaked.  Unfortunately I got a little ahead of myself when removing it and I lifted a trace.  I replaced it with a memory cap and did an OK job, but the lifted trace still annoys me.  It was otherwise a perfect MPU.

The right flipper was weak, so I couldn’t get multiball started, because I couldn’t make the Firepower top-capture shot.  But worst of all, the roulette wheel had dirty switches, which meant that there was no way to win roulette and the game would have to time-out every roulette spin.  Terrible!

I did immediately start looking for a topper, and found one locally. I cleaned and reinstalled it and it looks great, or at least as good as that topper ever looked.

Around this time, I bought my Spring Break and got sidetracked, since I’d never even played Spring Break.

After almost a year, I’m back trying to play Monte Carlo. First order of business was the roulette wheel.

The spinning bit is held on with a set screw that might be accessible without removing the assembly. Removing the whole assembly is a good idea to clean it. But if you remove the six screws holding the window on, then take the set screw out, you can probably lift the wheel out.

The wheel has twelve switches and I guarantee they’re all dirty.  I cleaned them with whatever scrap of paper was in my pocket and now it works pretty well.

I also put new foam washers to hold the window on. Now, the window is much closer to level with the playfield.

Now, I went to play it, and the game wouldn’t kick out the third ball to start multiball. I noticed while in test mode (testing the wheel) that switch 42 was stuck closed. The manual says that’s the trough. How can the trough have only one switch? I have no idea, but that’s all it has. On that one switch, the backing blade was bent against the playfield-touching blade.  I adjusted it, and now I have multiball.

Still to go:

  • Right flipper too weak.  Left flipper too, perhaps, but we’ll see.
  • A couple light sockets are bad. Target #5 is burned out, and the bulb is the most inaccessible light I’ve ever seen on a playfield.
  • +5V filter cap hack on transformer panel should be cleaned up
  • add redundant +5V/ground lines on MPU-driver cable
  • blown transistor for the flash lamp on the roulette wheel; lamps are missing from their sockets because they’re locked on (and burned the playfield!)

I bought a Star Trek; or, how not to drill a lock

A friend posted a link to a $400 Bally Star Trek on Craigslist. It was clearly bombed out, but I was looking for a restoration candidate. I went for it.

The seller said he didn’t have the head key. This meant two things: first, it was going to take a  big vehicle to move it back to my house. Second, the computer was going to be corroded. But the game was mostly working, how bad could it be?

I a U-Haul van, a little Ford Econoline, at the place near my house, and headed to the seller’s place. I got there around 5 and after some smalltalk, I paid and then started figuring out how to get the game in the van. I have skates so it wasn’t too bad. I got the front legs off and we got the front of the game onto the van; then, the back legs off, and slid the game right into the door latch of the van.

That’s right, an ’80s Bally game won’t fit in an Econoline van with the head on.

Fortunately, I was somewhat prepared for this eventuality and had my drill and a bunch of bits. But I didn’t think carefully about how the backbox works and spent two hours trying to open a door instead of just lifting the glass out.

I finally lifted the glass out in the relative dark and got the game home in three pieces: head, cabinet, and glass, which I won’t put back in until I have a proper lift channel on it.

Anyway, I bought the game in early November and am just starting to shop it. Eventually I’d like to restore it, but this is at the end of a long list of projects.

Williams EMs Sometimes Have Interlock Switches

I decided to spend a few minutes trying to fix my Spanish Eyes.  It just wasn’t getting power at all.

I stared at the schematic for a while and chatted with Chris a bit, and he said, “Is there an interlock switch?”

Yep, sure enough, there is.

Gottlieb and Williams games, particularly those with three-prong power cords, have interlock switches and the coin door must be closed for operation. It is even rarer to find one that has not been bypassed.

And it’s not in my schematic!  I don’t know why.  I might guess that it was a factory option, on some games, but I know of other Spanish Eyes that don’t have the interlock switch. It looks factory, and I can’t imagine anyone ADDING an interlock switch.

(An interlock switch cuts power when the coin door.  Most video games have them on the back panel, and some games, particularly early ’80s Atari games, have them on the coin door.)

Spring Break restoration notes

Old notes are bulleted, with inner bullets updating the work I did:

  • Battery corrosion.  This had one of the “DataSentry” style black batteries of doom.  … I have so far removed the battery but not cleaned the damage.
    • Ultimately, I just stopped.  I have parts to rebuild the reset section, but it’s working; why fight with it?
  • Computer has been trashed.  Like every 80B computer, this has a piggyback board arrangement where the solder joints fatigue and crack. … [T]his involves desoldering the board so I can work on the underside.  Unfortunately someone decided to go to war with the thing on the top side.  I did finally get the board off, but I am afraid I have damaged the plated-through holes.  I obliterated at least one pad on the bottom and damaged another.
    • I bought one of the GPE daughterboards.  Highly recommended.  The redundancy that this board adds helps make up for my mistakes, and Gottlieb’s mistakes.
  • Ramp cracked at entrance badly.
    • I have a new ramp, but it’s not installed.
  • Sounds lacking.  So I can hear some correct sounds, but mostly it’s static.  Can’t hear the music. I want to take a look at this, but there’s no reason to until grounds are verified.
    • I did put this off until after the ground mods, but the ground mods weren’t required.  All the grounds in this game are one big common (eventually) and that was easy to verify.
    • The actual problem was one or more bad ROMs on the sound board. I verified this by swapping parts with my Monte Carlo, which had a working sound board. This was much easier than trying to go at it with an oscilloscope… which I also did.
  • Ground mods not done.  I suspect this is causing sound problems.  At least one set of pins (this game has five) is burned badly.
    • I did the major ground mods.  Didn’t fix the sound (not surprising).  I’m not happy with them, though, because it means permanently rerouting a cable in a way I just don’t love.  I may try and come up with another method the next time I do this.
  • Lots of lamps missing.
    • Bad sockets and bad bulbs. I need to solder some sockets “shut”, but that’s about it.
  • Driver board has transistors replaced with the twisted-leg hack.
    • Replaced with CEN-U45.
  • Black rubber on playfield.  Ew.
    • Yeah, still haven’t had time to shop the game.

Maybe they’re all blown.

In the vein of the Maybe they’re all burnt out rule, I recently got a Gottlieb Monte Carlo  and none of the pop bumpers worked.

I got really lucky with this one. Each pop bumper is fused separately, but each and every one of them was blown individually. I could have gone checking the power train back to the transformer, but I was sort of smart and checked the fuses first. I say sort of smart because if I was legitimately smart, I would already have pulled every fuse on the game and made sure they were as originally specified, and I haven’t.

All of that said, why did three fuses die simultaneously? Well, the game was moved several hundred miles on the back of a truck. The drop target reset fuse had also blown. Maybe the fuses were just old, or perhaps I have another problem. In any case, though, they certainly needed to be replaced.

I bought a Spring Break

Chris goes to the Captain’s Auction Warehouse coin-op auction regularly, at least recently. I started getting some bids in on some weirder titles that are going for reasonable prices. First I got a Spanish Eyes, then a Monte Carlo.  Most recently I picked up a Spring Break for $500, plus premiums and tax, which are actually pretty steep.

But I was happy to get it. The game is complete. The playfield is a little rough, but they’re still available. The cabinet is very good.

So far, I’ve found the following problems with it:

  • +5v regulator pot was bad.  They’re all bad, unless they have been replaced.  Mine was running a little north of +5v and the adjustment pot just didn’t work.  I replaced it, and it’s OK.
  • Battery corrosion.  This had one of the “DataSentry” style black batteries of doom.  Unlike my Monte Carlo, which is a few months older and had a beautiful, clean computer, this one has some damage in the reset section.  I have so far removed the battery but not cleaned the damage.
  • Computer has been trashed.  Like every 80B computer, this has a piggyback board arrangement where the solder joints fatigue and crack.  The solution is straightforward: resolder the pins.  The difficulty is that this involves desoldering the board so I can work on the underside.  Unfortunately someone decided to go to war with the thing on the top side.  I did finally get the board off, but I am afraid I have damaged the plated-through holes.  I obliterated at least one pad on the bottom and damaged another.  This won’t be too hard to mitigate, but it probably would not have happened had someone done good work to begin with.
  • Ramp cracked at entrance badly.
  • Sounds lacking.  So I can hear some correct sounds, but mostly it’s static.  Can’t hear the music. I want to take a look at this, but there’s no reason to until grounds are verified.
  • Ground mods not done.  I suspect this is causing sound problems.  At least one set of pins (this game has five) is burned badly.
  • Lots of lamps missing.
  • Driver board has transistors replaced with the twisted-leg hack.  I have the right transistors and I’ll fix that.
  • Black rubber on playfield.  Ew.

On the upside, a lot of lamps DO work.  The flippers are pretty strong.  The cabinet is very good, other than some duck tape glue that should be pretty easy to clean off.  The translite is a little faded, but not too bad.  I dropped in the regulator and computer from my Monte Carlo, and that gave a lot of hope.

You don’t play the paint.

Want to save a lot of bucks buying a pinball?  Look for a “player’s” game, not a “collector’s” game.

Collectors worry about numbers of plays, scratches on the cabinet, “orange peel” effects on the playfield, “ball swirl” marks. They ask, “Is it home use only?”

I suggest asking instead: “Is it fun?”

Always remember: You don’t play the paint. A little wear around scoops, inserts, or a few cracks in the paint can bring down the value, sure, but it generally doesn’t affect play at al.

Massive damage to the paint, or a completely worn out playfield, could seriously affect play. And it’s OK to worry about cosmetics. But it can become an obsession, and it’s not worth it.

Related, You don’t play the cabinet. It is crucial that the cabinet is square, and also important that it keeps out pets, spilled drinks, and dust. Does it matter if the cabinet is faded? Well, sure. It affects the value. If ugly enough, it can annoy one’s spouse.

My Kings of Steel has some cabinet damage. Is it obvious? Not really, because it is cleverly hidden by Black Knight 2000 and High Speed..

That said, I have games where I would swap the playfield, or touch up the cabinet. There is heavy damage and it would improve the cosmetics. But there’s a cost to these, both in money and time. It’s OK if they are not cosmetically perfect.

It’s a pinball machine – not a shrine. – “Shaggy”