General Wall Game Circuit Board Repair Tips

This is the page to read if you only want an overview of game repair.

Typically, when you come upon an old Gremlin game, it will power up, but will not work properly.  Here's what you can do in order to get that game functioning again:

1. Precautionary Note: It is assumed that only those with at least basic electrical knowledge should attempt to repair a wall game.  This includes a healthy respect for the dangerous and lethal AC voltages which are contained within these games.  Unplug the games while cleaning and repairing.  Use extraordinary caution when testing the game, or operating the game "out-of-case" or with the cover(s) removed.

2. Carefully remove the push-on circuit boards attached to the very large main circuit board.  With the power off, use a Dremel-type tool to power clean the post contacts on the very large main circuit board.  Do not grind - just clean the posts.  The mating sockets on the smaller circuit boards are probably also corroded.  These are more difficult to clean.  Try small jeweler screwdrivers, toothpicks, and copper wire which has been roughened with diagonal grooves to assist in the removal of the oxidation.  Use a fiber cleaning stick to clean the inside of bulb sockets.  As an alternative, use "CLR" cleaner, available in supermarkets, on a q-tip or toothpick to clean away oxidation.

2. The electronic components which fail most frequently are the diodes and capacitors.  Diodes are best tested with a multimeter in ohmeter or diode testing mode.  Either analog or digital models will work for this, and they can be acquired for under $10.  Diodes are like one-way valves.  Basically, electricity can flow in one direction, but not the other.  If electricity flows in both directions, or in neither direction, the diode is defective and should be replaced.

Capacitors cannot be fully tested without proper test equipment.  The non-technical approach would be to replace all electrolytic capacitors on the board, test the board for proper operation, then replace the remaining capacitors if it still doesn't work.  I use a Sencore LC102 Capacitor Analyzer, which tests capacitors in-circuit or out of circuit, and only replace those capacitors which test defective.

3. Integrated Circuits (ICs) are difficult to test in-circuit.  One collector wrote me, and told me that he was able to repair his game by replacing every capacitor and IC on the board.   This might actually work, but will be costly and time-consuming.  I use logic analyzers (those clip-on LED arrays that indicate the logic state of each pin on the IC), a logic probe, a digital pulser, and an oscilloscope to test ICs in-circuit.  Any socketed ICs, I remove and test with a B+K Precision Model 864 Universal Device Programmer used in IC component test mode.

If you need to remove or replace any ICs, 1) Use only a very low-wattage soldering iron or proper desoldering equipment to remove them.  2) Replace the IC with an IC socket so you can more easily test and replace them in the future.

4. Failed transistors are also difficult to test in-circuit.  I use a Sencore "Cricket" transistor tester, which allows them to be tested in-circuit or out.  I have found very few bad transistors on my Gremlin logic boards.

5. The RF remote control transmitter and receiver board must be matched and aligned.  The factory alignment procedure requires an oscilloscope.  If you have already tested the components, then alignment may be your problem.  Contact Bob Carroll for a copy of the alignment instructions, until he finds the time to add that information to the web site.

Finally, here is a link to our compilation of technicians providing repair services.