Converting your Pachislo machine to accept quarters may be illegal in your state. If you're unsure you should check the law. This information is provided to assist people in converting their machines where it is legal. If you know this is illegal in your state then do not do it.
Converting a Pachislo machine to accept quarters is actually quite simple. Originally, the machines are setup to accept tokens only. Fortunately the tokens are very similar to quarters, except that they're about 1/32 of an inch larger.
The coin hopper will already handle quarters without modification. If you've never cleaned your hopper before then it might be a good idea to disassemble it and remove all the little metal shavings from the softer metal tokens. If you wish to test the hopper then go ahead and fill it with a few hundred dollars worth of quarters and play for a while.
To dump all the tokens from the hopper, reach around to the right side of the machine and find a toggle switch near the connection plug. Move the toggle to the on position while the machine is powered on. It might be a good idea to have a bucket or something similar nearby.
The only component of the machine which needs modification is the coin mech. Open the machine and locate the coin mech on the door. Disconnect the electrical wiring by pulling the plugs apart. As your facing the coin mech, on the left side will be a moveable latch that holds the mech in. Lift the latch up and swing the coin mech out towards you. The right side of the coin mech is held in place by two plastic dowels/tabs that slide into holes. After you swing the mech out, slide it to the left to completely remove it.
Now that you have the coin mech in your hand, it's time to clean the coin path. The coin path's for these machines often have rust in them. Take a serrated knife or something similar and scrape off the rust. Now locate the optical sensor on the back of the coin mech. You should see a small black box with wires coming out of it. The box is in the middle of the coin mech, towards the right edge. The box is held to the coin mech using a little plastic tab.
The optical sensor is at the tip of my index finger
A photo of the sensor removed
Remove the optical sensor and grab yourself an exacto knife. Scrape about 1/32 of an inch off the bottom of the sensor box so that it sits lower in the coin mech when you put it back in. The idea is to make an adjustment so that the smaller quarter will be accepted. I would recommend scraping a very small amount at a time and testing the coin mech to see if it accepts quarters.
When you put the sensor back in the coin mech, you'll have to put some material on top of it to wedge it in. You can use paper, wood, plastic or anything that helps to fill the gap. If you accidentally shave the sensor too much, you can put a wedge underneath and on top of it.
That's all there is to it! Just a couple minutes with an exacto knife and you're all set for quarters! The only problem you'll have is coming up with enough quarters to fill the machine!