The complete Bally Fathom pinball page
Playfield Structure
Playfield Parts
Replacement Parts


Restoration and repairing is one of the more difficult tasks. If you have no experience and think you can't do it, leave it! Find somebody who knows what to do and how it has to be done.
Bally used parts of the fourth generation on the Fathom:
Power Supply AS2518-54
MPU Module AS2517-35
Sound Module AS2518-61 [Squawk & Talk]

Before you start go to and read the guides for repairing and restoring pinball games. It's the best resource you can find on the net providing answers and solutions to every problem related to pinball machines.

Think of the age of the Fathom for example. It's been over 20 years since its manufacture! How many cars of that age do you know still operating proper? So believe me, there is always some work to do after buying a machine! Here is just a short check list:

  1. Forget the power plug! Do not turn on the machine!
  2. First of all inspect every piece of the machine – especially the parts under the playfield and behind the backglass!
  3. Remove the backglass and take a look at the CPU and the batteries. Are they leaking? Is the board damaged by battery's acid?
  4. Check all fuses.
  5. Check all connectors for broken or missing wires and signs of heat damage.
  6. Inspect the power board. Search for screws or other metal parts which might be on the board because of the transportation.
  7. Carefully plan what has to be done.
  8. Have the right tools on hand [e.g. screwdrivers, nut drivers, wrenches, digital multi-meter, etc.]
  9. Go through Clays restore and repair guides [see above] and do at least the work described on the right.

Working on the visual appearance of the game:
Just a few things about here cause most is covered by the «Maintenance»-section anyway. If I have time I will add some more details. To prevent you from easily messing up a game take a look at these points:
  1. Backglass – It's hard to do any touch up work on a Fathom backglass since it has been printed using the four-coloured technique. If there are just a few weak points, leave it as is. If you can't live with it, get another one through ebay or watch the newsgroups. To prevent further damage check it for loose paint or weak mirrored inserts.
    Go to for details.
  2. Playfield – some kind of wear is normal for a machine of that age. Extensive wear above the bumpers and the A-B-C lanes can be found on several machines. If you want to do touch up work see for advice. Again, if you have no experience - leave it and let some expert do the work.
  3. Cabinet / Backbox – I prefer one with a few scratches and some wear since the game is over 20 years old. If there is major damage see Clays Restore Guide for tips for repainting the cabinet / backbox.
  4. Plastics – Reprosets can be found here. I have no information about their quality yet. Price for a set is 150 US$. Bumper caps can be found at PB Resource. The new caps/rings will fit to the old bumper bodies but you might be not able to use the screw holes.
If you are impatient, here is a brief list of some tasks I highly recommend before turning on the game:
  1. Remove the NiCd-battery to prevent the MPU board from acid damage. [The game will work without the battery but will loose settings and highscores when you turn it off.]
  2. Replace the VJ248 bridge rectifiers Bridge Rectifierson the power module cause they are to small [200 V, 8 A]. Use 25 or 35 Ampere bridges instead. I prefer solder them on top off the board and adding aluminium heat sinks [don't forget some heat sink compound between the sink and the bridge] to let them cool easier. There should be 1/2" space between the board and the bridge to have good air flow underneath.
  3. Replace the 11,000 µFd at 20 V filter capacitor [C23] Bridge Rectifierson the voltage regulator / solenoid driver board since they last for about 10 years. Use higher values than 11,000 µFd and 20 V if you want but never lower!
  4. Upgrade the voltage regular / solenoid driver's + 5 Volts by jumpering TP1 and TP3 on the voltage regulator / solenoid driver board with a short wire to take away unnecessary strain from board's connectors and header pins.
  5. Resolder the transistor Q5 on the MPU Q5 Transistorboard in some distance to the big resistor. The heat of the resistor heats up the transistor which can cause resets during a game.

I noticed that the upgrade of the power supply increases the performance of the game entirely: Flippers are strong and powerful, bumper coils are responding better and faster.

Useful: Replace the sockets for the #555 lamps [wedge style] with bayonet sockets so that you can use #47 light bulbs [150 mA / 0.945 W] to reduce the strain on power supply's transformer, connectors and bridge rectifiers.