What You Actually Need to Know Before You Start
The Trax 6A is a Data East pinball machine from 1991. It uses a standard 68HC11-based WPC board setup with some quirks unique to the motorcycle theme. Passtime Controls makes replacement capacitors, transformer kits, and display solutions for vintage pinball machines. If you're looking to install a Passtime upgrade kit on your Trax 6A, this guide covers what actually works and where people mess up. Start with the power supply. The Trax 6A's original capacitor values degrade over time just like every other WPC machine, but there's a specific problem that catches people off guard. The main filter capacitors in the power supply are under more stress on this particular machine because of the solenoid load from the motorcycle engine sound module and the extra scoring relay circuits. I learned this the hard way when I replaced caps on a Trax 6A and it kept throwing a power-on self-test fault on the third attempt. The issue wasn't the caps I had just swapped -- it was the auxiliary 5V rail decoupling. I ended up adding a 4700uF cap across the aux 5V rails and the fault cleared. Passtime's standard capacitor kits don't include that workaround because they're designed for generic WPC platforms. Remove the backbox and flip the playfield over. You'll see the main game board stacked on top of the power supply. Disconnect everything from the main board before you start pulling it. Label the ribbon cables with masking tape and a sharpie -- not your phone camera. Those connectors get confused easily and backwards seating will fry something. The Trax 6A uses the standard WPC ribbon cable layout but the power board connector has a slightly different pinout than later Williams machines. Don't assume you can swap boards between Trax and later models without checking the diagram.
Capacitor Replacement Details
Passtime's kit typically includes 4700uF or 6800uF replacements for the main filter caps and smaller values for the logic supply. The Trax 6A specifically calls for: Main filter capacitors: 4700uF 400V rated. Use low-ESR types if you can find them. I've had cheaper caps fail within a year on high-vibration machines like this one. Logic supply caps: 4700uF 16V and 1000uF 50V depending on which revision board you have. There are two versions of the WPC board used in Trax. Check the part number printed on the PCB. If it ends in F it's the later revision and uses slightly different values.
Decoupling caps on the aux 5V: 4700uF as I mentioned above. This is the step most guides skip.
Get the Full Details
Transformer and Diode Work
If your Passtime kit includes a transformer upgrade, disconnect the machine from wall power and discharge any residual voltage on the primary side before touching anything. The Trax 6A transformer runs hotter than most WPC units because of the additional coil load from the motorcycle simulation circuitry. I've seen originals crack from thermal stress around the epoxy potting. When you install the replacement, torque the mounting screws evenly. Overtightening distorts the core and introduces hum into the solenoid circuits, which makes the flipper timing feel mushy. The flyback diodes on the solenoid drivers also degrade. Check all of them with a multimeter in diode mode. Forward voltage should read between 0.5V and 0.7V. Anything below 0.3V is leaking and needs replacement. I replaced a batch of these on a Trax 6A that had intermittent solenoid firing during rapid sequences -- the engine rev sound would cut out mid-cycle because a fried diode was dumping voltage back into the driver board.
Display and Coin Door
The Trax 6A uses a Nixie-style numeric display for the score and a separate dot matrix for attract mode graphics. Passtime makes LED replacement panels for some WPC machines but check compatibility before ordering. The Trax display socket has a different pin arrangement than the later WPC-95 displays. If you're keeping the original tube display, inspect the flex cables that run from the display board to the main board. They crack along the fold points after 30+ years. I found hairline fractures on a unit I was working on that caused random character dropouts. A careful continuity check along each trace reveals which ones are compromised. For the coin door, Passtime's upgrade typically involves replacing the old reed switches with solid-state alternatives. The Trax 6A coin mech connections are straightforward but the harness runs under the playfield and can get pinched during reassembly. Route it carefully and leave a little slack near the connectors. Tight routing causes intermittent faults that are miserable to diagnose later.
Common Pitfalls
People often skip the game protect circuit check. The Trax 6A has a game protect relay that can stick if the coil is worn. Test it before you close everything up. A sticking relay causes the game to reset randomly during play, which looks like a board problem but is actually just a mechanical fault. Another thing: don't mix old and new capacitors on the same rail. I've seen technicians put fresh caps next to originals that were never touched, and the old caps pull the whole rail down. Replace everything on each rail together. The Passtime kits are good but they aren't complete solutions for every Trax 6A issue. If you're dealing with persistent communication errors between the main board and display, a capacitor swap won't fix it. That's usually a bad solder joint on the display board connector or a failing 68HC11 chip. I had one machine where the display would go blank during extended play. Turned out the IC socket for the 68HC11 had corroded pins. Cleaning the socket and reseating the chip solved it. Passtime doesn't sell replacement sockets for that IC, so you'd need to source one separately or redesign the board with a socketless approach.
Where Passtime Isn't the Answer
If your Trax 6A has severe playfield wiring damage -- and a lot of them do after 30 years -- a Passtime component kit won't address that. You'd need to rewire the playfield separately. Passtime's strength is the power supply and display side of things. For coil replacements, midland or PinballLife is usually more practical. And if the glass is cracked or the marquee is faded, you're looking at a completely different vendor chain. The installation process itself is roughly 3 to 5 hours for someone who knows the platform, maybe 6 to 8 if you're doing it for the first time and double-checking connections.
