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Repair & Maintenance Log

09/14/07: Acquired game.

09/27/07: Replaced one of the PIA 6821 chips. I only got about two days of play out of the game before the MPU board decided it wanted a new PIA. Otherwise it only took a few new bulbs and a shooter rod cleaning to get the game up and going.

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PIA chips (U10 & U11).

02/23/08: Okay, well I actually had two electrical gremlins with this game. Sometimes the game would not start at all. And sometimes the game would randomly restart for no reason. The 6821 chip fixed the first problem. After a few months I finally got off my butt to look for the second problem. Predictably the big C23 +5 volt filter cap was bad. As usual, thanks go Clay's repair guides at marvin3m.com.

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New C23, before (left) and after.

While I had the regulator board out of the game I decided to make the ground modifications outlined in Clay's repair guide. My board looks to be in pretty good shape. One of the traces under the flipper enable relay was blown out and bypassed. Otherwise there was little sign of previous repair.

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Blown out trace under the relay.

03/18/09: I'm tired of farting around with intermittent bulb sockets so I decided to solder them shut. First I used a mini wire wheel in a Dremel to shine up a spot between the socket body and the mounting bracket (supply voltage). Next I placed a dab of paste flux on the spot. Then I bridged the body and bracket with a solder blob using a 40 watt iron and a wide tip. Despite my efforts at cleaning the spot and adding flux, the metal doesn't seem to tin very well. The end result is ugly, but it seems to work and it's easier than replacing sockets. I tested all the sockets for shorts before turning the game back ON.

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Socket shined up (left) and soldered shut (right).

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If the socket continues to be cantankerous, I pull the control wire off the tab and solder it right to the spring thingie in the middle.

I also adjusted all the stationary target switches and replaced any missing switch capacitors. I used .047 micro farad caps. What a difference in switch sensitivity! Despite what some may say, bad switch capacitors should be replaced, not simply removed.

While I was at it, I also did a mini-shop job. I replaced all the bad bulbs, cleaned or replaced all the rubber and cleaned and waxed the playfield.

03/20/09: Fabricated new ball guide plastic. The mid-level clear plastic at the top of the "Time Warp" lane was missing its hook. Balls shot up the Time Warp lane were not smoothly hooked down the shooter lane and would occasionally bounce back into play. I believe the broken plastic was caused by a misaligned top arch rail. The end of the arch rail was protruding into the shooter lane and plunged balls would sometimes ricochet into the tip of the plastic. After fixing the arch rail, it was time to replace the plastic.

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Broken plastic.

First I bought a sheet of Lexan at Home Depot. Home Depot sells small inexpensive sheets of just the right thickness. I used the old mid-level plastic to trace a pattern on a piece of heavy paper. I used the upper level plastic to trace in the missing hook. Without removing the protective film from the Lexan, I sprayed some spray adhesive to my pattern and stuck it on the Lexan sheet. Next I cut out the Lexan with a coping saw. A power band saw or scroll saw would have been nice. The hand saw was tedious and slow going, but it worked. Instead of trying to make perfect cuts, I just went back and cleaned up all the edges with a small drum sander in a Dremel.

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Paper pattern glued onto the Lexan sheet.

Drilling the new mounting holes was also tedious. I started with a small drill bit and slowly worked my way up through progressively larger bits. The larger bits wanted to catch on the Lexan so I ran the drill backwards and melted rather than cut my way trough. I used a soldering iron to pop the metal standoffs from the old plastic. Unfortunately some of my new mounting holes had drifted. So I used a small reamer in the Dremel to elongate some of the holes. But the end result was pretty nice looking if I do say so myself. Before installing my new plastic, I peeled off all the protective film and lightly flame polished all the edges.

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Finished plastic back in the game.

The playfield has two green inserts associated with the 2x multiplier. Even with #44 bulbs I thought the green inserts looked dim compared to those of other colors. So I decided to pop in a pair of green Ablaze LEDs (www.pinballlife.com). The effect was just what I was looking for. Sort of... Unfortunately the LEDs don't provide enough load to operate the Bally lamp driver circuits. The lower 2x green LED worked because it's tied to the upper 3x insert. Thus the bulb in the upper 3x insert provided proper loading to the driver circuit. However, the upper 2x green LED did not work because it's on its own circuit with no additional load. So I got the upper 2x green LED to work by tacking a 1k ohm resistor across the socket as shown below.

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Green Ablaze LED with an extra 1k ohm load.

04/03/10: New playfield glass.

12/10: Acquired reproduction playfield plastics from Classic Playfield Reproductions including prototype plastics options.

10/22/11: Some previous person had replaced MPU NiCad battery with a remote battery circuit (which is good). But I like the modern non-volatile memory chips now available (and I had an extra). So I replaced the remote battery circuit and old RAM chip with a non-volatile memory chip from Tom Callahan at pin-logic.com. The chip comes with a small circuit board such that the wider new chip can piggyback on the old narrower socket. Assuming the old socket is healthy, this is a plug and play modification. I folded down the TP6 wire hoop so as to not interfere with the new larger chip.

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Original RAM chip and remote battery circuit (white and gray wires).

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New non-volatile memory chip and no battery circuit.

03/24/12: Installed standard-keyed (751) lock on coin door.

02/07/13: Installed reproduction prototype backglass from Classic Playfield Reproductions. This glass is a lot darker than the production glass. I switched all the backbox lamps back from #47 to #44 bulbs. The glass is still darker than I'd like.

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Reproduction prototype backglass.

11/19/15: Fixed the non-working 100,000s digit in the player two display. Maybe. Problem seemed to be with the connector J1 pin 9. I reflowed solder to the header pins. All the digits then functioned normally so I left the connector as is. I hate these daisy chained display connectors.

I also replaced the left coin drop plate which had been slightly vandalized. While I was at it I cleaned some of the other parts under the coin drop casting.

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New left-side coin drop plate.

01/31/16: It took five years, but I finally got around to installing my reproduction playfield plastics from Classic Playfield Reproductions. The set included the optional prototype plastics which is what I used. As usual I applied a Mylar undercoating to all the new plastics I planned to install. The Mylar helps protect the art from screw heads and other protruding hardware. I pealed the backing off a sheet of Mylar and taped it sticky-side-up on table. Then I placed my plastics right-side-up on the Mylar. I flipped the whole thing over and used a razor blade to rough cut out all the pieces. Then I used fresh razor blades and an X-Acto knife to trim the pieces and cut out all the mounting holes. A finger nail helps burnish the Mylar onto each piece. I didn't bother with any of the three mid-level transparent plastics. My existing pieces were in reasonable shape. And I didn't feel like messing with the metal posts which are crimped into the old pieces.

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New plastics stuck to a sheet of Mylar.

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Prototype art.

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Prototype art.

Somewhere along the way I acquired a set of custom drop targets. I installed those as well.

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New drop targets.

My new drop targets were not reliably resetting. I stared and poked at this thing for an hour before it occurred to me (felt like a dumbass) that the reset bar (green arrow) was not properly leveled. The reset bar must be readjusted each time the drop target bank is reassembled. The reset bar is adjusted via the reset spacer blocks (red arrows) which are held to their shaft by set screws. Once I got the reset bar properly leveled, the targets reset just fine. The guy who engineered this thing must have been paid by the hour. Somewhere between Paragon and Future Spa the spacer blocks were eliminated and the pivot brackets and reset bar were combined into a simple, ridge, non-adjustable, singular component.

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Drop target reset bar adjustments.

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Done!

01/31/16: Added remote volume control. I wanted to be able to fine tune the game's volume without always pulling the backglass. I looked to my Xenon for inspiration. Xenon has a remote volume control inside the coin door comprising a 100 ohm potentiometer. Xenon has a different sound board, but uses a similar output amplifier circuit. I figured what works for Xenon would work for Star Trek. So I bought a replacement 100 ohm potentiometer.

I mounted my remote volume control behind the cash box using a hardware store bracket. It's an easy reach from the coin door. I duplicated the speaker circuit from Xenon. The negative speaker wire is extended to the low side of the potentiometer. The positive speaker wire is removed from the speaker and extended to the high side of the potentiometer. A third wire is run from the wiper back to the vacated positive speaker terminal.

I set my remote volume control about halfway. Next I set the game volume from the sound board to about what I wanted. Then I readjusted the remote volume control to exactly what I wanted. Any further adjustments can be made right from the coin door.

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Remote volume control.

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View from the coin door.

03/18/17: Bumper sockets are my nemesis. I can clean them, adjust them or replace them and I still end up with one or two that give me unreliable contact. So I dispensed with the sockets all together. I decided to take advantage of the LED's long life expectancy and hardwire them right into the game. I picked frosted warm white LEDs from CoinTaker. I'm usually of the opinion that white LEDs are too harsh, but these warm whites blend in reasonably well. Also, I find that the holes in the bumper assembly are slightly offset to the inside of the corresponding playfiled holes. I assume that's to pinch the ribbon leads of the old socket. But it gets pretty tight when switching to regular wire. I used a hobby knife to ever so slightly bevel the playfield holes. The new wires are still pinched in place which keeps the LED suspended in the bumper body and (I hope) sufficiently insulated from vibration.

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Lead wires soldered directly to the LEDs.

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I beveled the lead wire holes ever so slightly with an X-Acto knife.

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The LED floats on the lead wires without touching the bumper body.

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Lead wires soldered under the playfield.

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The warm whites blend in reasonably well with the existing incandescent GI.

03/30/17: Rectifier board rebuild. The controlled lamps on this game were dim and I suspected a failing rectifier BR1 on the rectifier board. I was measuring a pathetic 2.8 volts at the board's BR1 test point TP1. Instead of replacing just BR1 I bought a complete rectifier board rebuild kit from Big Daddy Enterprises. I was a little surprised that the kit came with no instructions because the rebuilt configuration is a bit different from the original configuration. This is probably obvious if you've done some research, but here's the gist...

The board has three 8 amp bridge rectifiers that are mounted to the solder side of the board and screwed to the transformer chassis which serves as a heat sink. The 8 amp rectifiers are considered to be undersized (especially BR1) which is a reason they fail. The kit includes 35 amp bridge rectifiers. But the new rectifiers are too big to fit on the solder side of the board and so are moved to the component side. The bigger rectifiers don't need the chassis heat sink, but there is some heat sink debate. Most people seem to agree that BR3 (solenoids) doesn't need a heat sink. BR2 (+12 volts) probably doesn't need a heat sink. BR1 (controlled lamps) "maybe" doesn't need a heat sink. The kit comes with only one heat sink which is for BR1. Don't forget a dab of heat sink compound which may or may not be included depending on the kit.

The kit also includes one set of high current fuse clips for the GI fuse F5. They come in their own little baggie, but don't get them mixed up because they don't look much different from the 10 regular fuse clips. I was a bit skeptical as I could not tell the difference.

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The Big Daddy kit. Note the assortment of header pin sections for piecing together the 20 pin J3. I had my own full-width header pin section which I used instead.

It would appear that a previous owner un-hacked J3 by unsoldering some wirers from the header pins and splicing them back into a proper connector. But what's with the dangling white/yellow wire at pin 13 (red arrow)? According to the schematics, this is the backbox solenoid bus, but is unused in this game. I'll just leave that pin empty when I replace the connectors.

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Is the old J3 connector hacked or un-hacked?

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Note the three black screws for securing the rectifiers to the transformer chassis. Note the tarnished high current fuse chips at the GI fuse F5.

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Here's the board separated from the chassis. Compare the three 8 amp rectifiers with a new 35 amp rectifier (red arrow).

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A board vice is a must. I got the board in the vice without having to remove the transformer wires.

The old rectifiers are difficult to remove because they're tight against the bottom of the board and their leads are folded over on top. I sucked away as much solder as I could on top. But I still had to rip away each rectifier with vice-grip pliers using more force than I would have liked. The board survived.

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That's a lot of de-soldering.

I made two ground mods which I think are probably unnecessary. The mods take stress off some plated through holes, but this board seems pretty resilient. I jumped from J3 pins 1-4 to J3 pins 14-20 and from J1 pins 1-2 to J3 pins 14-20

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Ground mods.

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The mounting screws are discarded with the old rectifiers. So I replaced all the old board standoffs.

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New components installed. Note that the new rectifiers are up off the board. This promotes air circulation and also permits the leads to be soldered from both sides of the board. I soldered every component on both sides.

It took days to get the game powered up again thanks to two amazingly aggravating problems...

Problem 1: I powered ON the board with connector J2 only. All the voltages looked good except for BR2. Instead of outputting 12-14 volts I was measuring around 75 volts! I pulled the board again, triple-checked my work, tested for shorts and scrubbed the traces with acetone. No luck. So I just decided to live with it. The problem was obviously a high resistance voltage leak. Note that BR2 is completely unloaded without connector J3. If, for example, I jumped a 100kΩ resistor between ground and TP3, the voltage pulled right down to 12 volts where it belongs. Good enough.

Problem 2: I misidentified a bag of ¼ amp fuses for a bag of 3 amp fuses. In retrospect it's hard to believe I wasted days on this. I needed a 3 amp slow-blow for the main game fuse F6. I went to my parts bin and found a baggie labeled 3SB. Each fuse was also stamped 3SB and my dumb brain immediately latched onto the idea that 3SB must mean 3 amp slow-blow. Nope. It's actually a series designation for Bel Fuse Inc. Obviously the game isn't going to work on a ¼ amp fuse. I "blew" through most of the bag before I began to suspect I was using the wrong fuse. Eventually I took a closer look at the fuses and noticed that each was also stamped as 250MA (i.e. ¼ amp).

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One of the eveil ¼ amp fuses.

In the end my new BR1 was putting out about 5.8 volts under load and all the controlled lamps were bright. I probably could have saved myself a lot of aggravation by replacing BR1 only. Rebuilding the whole board is not a bad idea, but it's a lot of effort considering the availability of brand new reengineered rectifier boards. I would not recommend this project to anyone who does not genuinely enjoy board work.

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Everything back together with new connectors.

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Done! Compare the bright controlled lamps in this pictures with some of the older pictures further up the page.