Taxi Maintenance Again

July 10, 2018 @ 00:02

So I've been meaning to replace the old battery-backed RAM in my Taxi pinball machine for a while, and so when I had nothing better to do on Sunday, I started poking around to figure out what I needed.

Got that ordered, and since I was on a roll, I replaced a bunch of bulbs that were out.

And then I started testing the power supply power...

At this point I was making a day of it.

We've been here before

I the process of figuring out what I've got, I realized that Williams actually labeled all of the circuit boards with a serial number, and the model number of the game it was intended for (or at least, came from).

Taxi is #553.

However, my main board is labeled 567 - Jokerz!. So is the power supply board. But the "auxilliary power board" is labeled 568 - Earthshaker.

All of this means that my machine has been through an extensive refurb before.

I checked IPSND too - nobody else registered the serial numbers.

And here too

Today, I started investigating why the "spin-out" launcher ramp wasn't working as well as it used to. I think it's because the launcher makes contact too high on the ball, but I haven't really finished the investigation yet.

One suggestion was to make sure the switch that registers a rotation around the spin-out bowl is just barely resistant, so it doesn't slow the ball down... and while taking the assembly out, I found a major part of the issue is a crack in the plastic.

But then, when I took the entire assembly out, I found more evidence of a previous refurb - someone "fixed" this by applying metal duct tape to the underside of the spinner, to keep the cracked chunk in place.

Curiouser and curiouser.

To Do List

So here's the next few steps:

Replace RAM with NVRAM

Who wants their high scores to disappear when shutting the machine off? Who wants to have to setup all the system settings ever time you turn the machine on?

Or more importantly, who wants leaky AA batteries ruining your main board?

Full details #1

Replace TIP-42 transistors in lighting matrix

I've already had issues with circuitry overheating - I bought the machine with serious damage to the interconnect board (J6 of course), so this task seems pretty simple and good for longevity.

You replace all the TIP-42 transistors and their 27-ohm current limiting resistors with much cooler MOSFETs (I ordered the IRF9530).

Full details #2

Replace power supply ZR2 and ZR4 with 91V diodes

The display takes 100V normally, but if you replace the 1N4764A zener diodes in the power supply with 1N4763A, it then runs at 91V, and it'll last a lot longer.

Easy stuff.

Full details #3

Replace capacitors in power supply

Caps get old. I used to repair engine control units in DSM cars, because when caps get old, they leak. $23, no brainer.

Also I think my big 18,000 mfd filtering capacitor is going.

Replace single bulb to right of "CAB" lanes

Unfortunately, I'll have to remove the express lanes to get to this one.

Finish fixing "spin-out" issues

I'm not sure if this is a level issue, or the playfield has sagged a bit, or if the appears-misaligned launcher is the issue - it could just be I need a new spin-out assembly.

What I have already done

Since I'm typing this up, here's what I've already done over the past over 15 years (I bought it in about 2002), roughly in order:

  • Rewired incorrectly wired flipper
  • Replaced flipper coils, switches, EoS switches
  • Replaced burned out GI connector (J6), jumped blown-off solder traces
  • Cleaned corroded battery residue
  • Replaced balls
  • Replaced entire left flipper assembly
  • Replaced launcher sleeve and spring
  • Replaced not-original Lola ROM with proper Marylin ROM
  • Replaced many, many bulbs
  • Replaced all rubbers
  • Replaced broken plastics:
    • Marylin "lights carry passengers"
    • Both slingshot
    • Side "lights carry passengers"
  • Properly secure knocker assembly