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How to Repair a Slot Machine

Slot machines are a primary producer of casino revenue and popular collectible items.
fête foraine 12 image by Nathalie P from Fotolia.com

Slot machines are a primary producer of casino revenue and popular collectible items. As a blend of electronic and mechanical components, slot machines will wear with age and require routine repairs. Complex repairs require the use of a qualified technician, but common repairs can be carried out by the machine owner. Changing the battery packs for the electronics, for example, is a common repair that slot machine owners encounter on a regular basis.

Locate the CPU board. It will be behind the hopper. Pull the black knob to remove the board.

Remove the old battery pack and solder the new one in place. Use a soldering iron to heat the solder, turning it into a liquid state so that you can work with the packs freely.

Locate the game prom socket and install an IGT clear chip. This chip clears the slot machine memory. Run the clear chip by switching on the machine. Watch the displays running numbers. When the cycle completes, switch off the slot machine and remove the clear chip.

Install the set chip in the game prom socket. This chip resets the slot machine‘s bill validator. Turn on the slot machine. When the bill validator reads “9,” “9 0” and “9 1”, you will know that the set chip has updated the validator. Turn off the machine and remove the chip.

Install the original game chip. You will still get error messages at this stage because of the clear and set chips. This is normal. Press the test button and hold it until the error messages disappear.

Replace everything as it was before and turn the reset key on. Close the outer casing of the machine and lock the cover. Now when you turn on the machine, you will get the “insert coin” message.

Things You'll Need:

  • Soldering iron
  • New batteries
  • A “clear” chip
  • A “set” chip


Replace batteries at least once a year. If you wait for a long time, the batteries may leak and cause further damage.

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