Slot Machine Will Not Accept Coins

Trouble Shooting Summit Systems Slot Machines

• Slot Coin In
• My Bally Slot Machine Will Not Accept Coins

Many of the electronic problems on the Summit Systems slot machines arerelated to the connectors at the rear of the reel assembly. All of thecontrols (inputs and outputs) to the controller board have to pass through these twoconnectors. Clean and burnish (brighten) the connectors. Sometimes a contactcleaner/lubricant can help after the pins have been burnished. Spray both the maleand female connectors for best cleaning effect.

You can buy slot machines at ebay, craigslist and many online auction sites. All you need is to decide is what exactly you are looking for as we have here for you used slot machines, some antique which are awesome Vintage collection like some of the old fruit machines.

One thing to mention is that in a casino I can do part swapping with the machine next to the broken one until the problem is solved. This can make things much easier for problem machines. If you don’t have this option then it will be a bit harder to troubleshoot. If the Machine works with coins then it is not in a tilt. Many machines simply had the pound slot disabled with a riveted plate. Many coin-operated machines in Germany would accept the 1992, 1993 and 1995 stampings of the cupronickel Estonian 1 kroon coin as a German 1 mark coin. This was profitable for users of the Estonian coins as the kroon was pegged to the mark at a fixed rate of 8:1.

Slot machines that accept coins were designed this way because when used constantly on the casino floor, hoppers could quickly fill. There is a coin level probe on side of the hopper that looks like a brass screw sticking inward toward the hopper bowl. This probe detects when coins/tokens are at a selected level, and will cause the subsequent. Coin In Error: Verify that comparitor is seated in all four acceptor clips: Verify that acceptor does not have coin(s) jammed: Verify that the coin optics is not blocked (below comparitor) Ensure toggle power switch in activated (if installed) 3100: Coin Out Tilt (Hopper) Check for and clear any jammed coins in the coin out channel.

Note: As I receive inquires about machine problems, I will try and add the cause andsolution to this page.

Identification of the Boards:

The Top board of the electronics is the 'InterfaceBoard' (Red Handle)

The Middle board is the 'Slot Controller Board' (YellowHandle) The battery is normally located on this board. Most boardshave the battery removed. This does not cause any problem with the machineoperation. See 'Battery Issues' in this section

The Bottom board is the Options Board which isthe interface to other machines when the machine is used in a progressive jackpot typearrangement (multiple machines are connected together). Normally, this board is notinstalled. However, if you purchase a machine with this board installed, you mayneed to keep the board in to have the machine play. The options board is also usedto control the sound while the reels are running. This is only if you have a soundboard in your machine. The sound board is usually located in the top section of theslot machine cabinet.

Over Indexing: (see Tilt Codes)

Over indexing can be caused by one of two things. Sticky release mechanism orfaulty (intermittent) encoders. If you suspect the encoders, go through the reelalignment procedure. This will most likely show up a faulty encoder.

Extra Coins Paid out (occasionally):

This usually happens when the clutch on the motor fails to engage or is weak. Tryadjusting the clutch device on the hopper motor. Also, the coin out switch may needslight adjusting, see the next paragraph

Extra Coins Paid out and Tilt, Flashing 0 or # with any win!

The slot controller board relies on the feedback from the coin activated switch on thehopper. Each time a coin passes through the feed mechanism it activates a lever andin turn activates a switch. This switch feeds the 'coin out' signal to the slotcontroller board. So first make sure that the switch is being activated by thecoins. To see if the slot controller board is registering the switch input performthe following test:

Note: Start with No tilt code should be present on the machine(see 'Battery Issues' to disable the tilt code retention).

1. Play a game, single coin:

2. During the game play, hold the coin activator lever up (on the hopper) to simulate acoin being fed out.

3. At completion of play, the meter should be alternately flashing a -8- and an 0. This code is coin out jam (switch closed)

4. When releasing the lever, the -8- should change to a -9-. Press the hopperreset and the -9- should change to a 1. 1 means it registered 1 coin as being fedout.
5.Then when you close the door (activating the door switch) the machine shouldresume play.

First thing is to determine if you get the -8-. If you do, the switchactivated by the coin out lever mayjust need adjusting. You can adjust the lever activated switch as there is a screwto accomplish this. The lever that the coins actuate has a roller near where thecoins exit the hopper. At the opposite end of the lever, there is normallyan adjusting screw that actuates a micro switch as the coins go out. The switch has to'toggle' with each coin out.

If you don't get the -8- tilt code, the slot controller board is not processing thesignal. You will need a new slot controller board or yours repaired. The chipthat buffers the hopper switch signal is the ILQ-74. Changing the chip may correctthe problem. We now have this chip in stock.

Coins Won't pay out (flashing 0 on the right Digit of the Meter Display):

1. Check to make sure that there are no coins jammed in the coin disk of the hopper andthat the disk can be rotated freely about 1/8 of an inch (or more). The electronicsto control the hopper are located on the interface board and will requirerepairs. The hopper also has a circuit board. Rarely, this board goes bad. If the hopper won't run, you get a flashing zero on the display along with the tiltlight. The flashing zero meaning that zero coins were paid. This problem could berelated to bad connections on the plug and jack assemblies on the hopper or the reelmechanism. To restart payout, press the hopper reset button and close the door(activating the switch on the top hinge of the door). After 3-4 seconds, the hoppershould activate. See the above paragraph for clearing the tilt and restarting thepayout! Also, see 'Battery Issues' to disable the tilt code retention.

Clearing the flashing Zero on the Right Digit of the display:

If the hopper runs, then pressing the hopper reset button and closing the door(activating the switch connected to the top hinge), should clear the flashing zero andallow the hopper to run. If the flashing zero stops for a few seconds, thencomes back, it's because the hopper won't run or the hopper switch is failing to signalthe coins going out. Also, see 'Battery Issues' to disable the tilt code retention.

Continuity test for the coin out switch of the hopper:

Testing for continuity using an ohm meter. 0 volts is either thenegative end of the battery or the black with red trace wire on the coin inswitch (easy to get to). The 'coin out' input resistor on the 'slot controller'board is R10. With the machine off, if you are measuring the resistancebetween 0volts and the end of the resistor that goes to the edge connector(circuit board gold pins), the resistance should go low (about 1 to 100 ohms)when the coin out switch is activated. If the resistance goes low, youhave good continuity in the machine harness and connectors and the problem isthe slot controller board. If the resistance does not go low, you have aproblem with connections in the system (usually the rear connectors of the reelassembly).

Testing with a volt meter (power on):
R10 should have about 3.5 to 4.0 volts on it with the coin out switch open(either end of the resistor). If the resistor has 5 volts, the optocoupler (ILQ-74) is shorted and will need replacing.

Repairs and Board Testing

Repairs and diagnostics are available according to the prices listedbelow:

You don't need to call, just pack up your boards, send them to us, Attention: DickHarkey. Be sure to include your name, return address, contact information and descriptionof service requested. Be sure to specify return method of shipment. Pack yourboards using some kind of protection between the boards (IE. Styrofoam, foam, cardboard ornewspaper). The slot controller board is subject to static electricity damaged andshould be wrapped in an anti-static material (pink bubble wrap or metalized film availableat most 'Mail Boxes Etc' and others. I usually will get back to you in 2-5 workingdays from receiving the parts. Note: The power supply is easily removed. This is the unit with the little on/off switch and the 2 LED's. On the leftside there is a recesses to reach in and pull it out.

Won't accept coins:

The machine has to be in a non tilt mode and the processor on the slot controller boardhas to be running in order to accept coins. If the machines accepts coins but doesnot register the coins, the slot controller board may be defective. There is an OEMchip in the slot controller that is no longer available and is always the reason for notcounting the coins in. You can order a replacement board or send in your board fortest. Sorry, I don't repair slot controller boards. If you purchase a slotcontroller board, I will apply the diagnostic fee toward the purchase of a new board.

Accepts and registers coins but won't start play.

1. If the handle is allowed to be pulled (handle release solenoid was activate) thenthe slot controller board is waiting for a game in progress signal from a switch. The switch is located on the side of the reel assembly and the two wire from the switch goto the back of the electronics mother board and plug in there with a 2 pin plug. Make sure that the plug is attached and that the switch is activated by the pulling of thehandle (launching of the reels).

2. If the handle is not allowed to be pulled, either the interface board is not turningon the solenoid for the handle release or the switch on the handle releasesolenoid/activate lever may need adjusting. (See above for board repairs and or testing).

Battery Issues: (The Battery is located on the SlotController Board) [Yellow Handle]

The battery is used for several things. It keeps track of the coins played, thenumber of coins in the hopper, the status of the last game play and of course maintainsthe last tilt code. To erase the memory, pull the jumper located next tothe battery. (The jumper has to be removed for 5-10 seconds for the board to losememory). When you turn the machine back on a '-0-' will appear in the coin payoutwindow. This code just means that the memory was re-initialized. When you press thehopper fill button, you are telling the machine that the hopper is full of coins(now). Typically the full count is around 2000 coins. So, if you hit a jackpotand don't have enough coins to pay out, you have to re-fill the hopper, press the hopperfill button and close the door. Closing the door signals the slot controller boardto continue paying out. Note: The battery is not necessary for correct operation ofthe machine. One customer found that without the battery, he would hit the jackpotafter power up and 20-30 plays. This is the only instance of a battery related issuethat I have heard of.

Coins Accepted, but Handle won't release

The handle release coil (located above the handle mechanism) has to be energized thruthe back connectors of the reel assembly to release the locking lever for the handle. Place a metal screwdriver near the release coil. If you feel the magneticpull of the coil, then the problem is mechanical. If there is no magnetic pull, thenone of the following applies.

1. The interface board is not energizing the coil
2. There is no connection thru the back connectors of the reel assembly
3. The interlock switch operated by the locking lever is not making contact
4. The release coil is open. This can be confirmed by measuring the resistance of the coil.

If the problem is mechanical, most likely there is a groove that has been worn into therelease lever. This is where the armature of the coil and the release lever come incontact with each other. The armature should be fairly easy to push and release thelocking lever. If it feels 'stick' lubricate or file off the groove in the releaselever so that it allow smooth movement of the armature.

Handle Release Issue: New and Old Interface boards notcompletely compatible. The old style interface board (red handle) had mechanicalrelays (black rectangles). The new style interface board has opto-couplers andTriacs (solid state). The old style interface board applied 120 volts to the handlerelease solenoid. This would be a gray/yellow stripe wire as the 120 volt source,and blue/white stripe as the return of 0 VAC. The new interface board utilizes 50VACto the handle release solenoid and still uses the gray/yellow wire.. The common orreturn for the 50VAC is a yellow wire. If you have thiscondition with old wiring connections but a new interface board, then remove and tape theblue/white wire from the handle release solenoid. Locate and make connection to theyellow wire somewhere in the machine to the handle release solenoid. You should endup with a gray/yellow wire and yellow wire on the each of the solenoid connections. Note: The 50VAC is isolated from the 120 VAC, this is why there is no power to turnon the handle release solenoid!

Tilt's often:

Please email me the tilt code, and I will put an answer to the tilt reason here on myweb site within 48 hours (unless I am on vacation).

Tilt's Codes Won't Clear

After pressing the Hopper Reset button on the power supply, the machines waits for thedoor to be closed. There is a switch mounted behind the upper hinge of the door andthe switch should be activated by the hinge (door) closing. There is about a 1second delay before the game is allowed to proceed. There should be a plastic piecemounted to the plunger of the switch. If the plastic piece is missing the switch will notbe activated by closing the door. The plastic piece is about 1/2 inch square andabout 3/8 inch deep. I have them in stock if you want to order it (complete doorswitch).

ILQ-74 Inputs and Outputs (switch buffer)

The ILQ-74 chip is used to buffer all the switch signals of the machine. It isthe most common failure for the slot controller board. IE won't read the coin in,count the coins out, etc. The following is a list of inputs and outputs. Note: All of the inputs go to resistors and then the ILQ-74 chip. So I am givingall the connections on the slot controller board. Use the battery - (minus) connection asthe common measuring point. Same as the black wire with the red stripe on all theswitches. You can order this chip from me if you have the skills to replace it.

• Connections are to slot controller board, to the input resistor to the input pin of the chip to the output pin of the chip.
• J/P RESET (Jackpot Reset located on the side of the machine). Pin 70, to R9 to Pin 7 of ILQ-74, output Pin 10 (if the output of the ILQ-74 is bad, the game is waiting for the signal to go high). Nothing will happen as long a this signal is wrong.
• Coin-In Switch (Located on the door under the coin mechanism. Pin 76, to R12 to Pin 2 of ILQ-74, output Pin 15 (won't register coins)
• Coin-Out Switch (Located on the Hopper). Pin 72, to R10 to Pin 6 of ILQ-74, output Pin 11 (doesn't count the coins out)
• Door Switch (Located behind upper hinge). Pin 74 to R11 to Pin 3 of ILQ-74, output Pin 14.

Note: While measuring the input or output of the ILQ-74 the related input and outputshould change state as the switch is being pressed.

Sounds and Sound Issues(Pictures)

Some machines were wired for sound and others only used the jackpot bell as coin-inindicator and win indicator. The machines that were wired for sound have a soundboard and speaker behind the upper light assembly. The sound board is interfaced tothe machine via a small board mounted to the cabinet just behind the reel assembly. The sound interface board has a 20 pin connector on the left and a 16 pin connector on theright. The most common problem with sound issues is that one of the reed relays onthe interface board becomes stuck (switch closed). By lightly striking the reedrelays (small rectangular black body) you can un-stick the contacts. The indicationis that a chirp kind of sound is generated when the machine is powered up.

There are 3 sounds generated by the machine. Coin-in (the coin-in switch isdirectly wired to the first reed relay (on the left). Reels running, this soundsignal comes from the option board. I have just designed a replacement for theoptions board (blue handle) for those who would like to get the reel sound running. The last sound is of course the jackpot or coins paid sound. This sound is generatedby the 'bell' circuit. 6.3 volts AC is connected to the interface board and theboard has the components mounted on it to rectify the AC to DC to drive the 5 volt reedrelay.

All of the sound boards that I have seen utilize opto-isolators for the input commands. You can troubles shoot the board sound board by performing the following.

1. remove the 12 pin connector on the side of the board.

2. Short pin 4 and 5 of opto-couplers U1, U2, U3 (respectively). This shouldactivate each sound. Pin 1 of the opto-coupler (H11B2) has a 'dimple' and you countcounter clockwise. So pins 4 and 5 are on the opposite side of the opto-couplers asthe input connector.

If the board makes sound, the problem is the interface board behind the reel assembly.

All Reels don't Spin when Handle is pulled or don't always spin

Turn off the power, pull the handle, If all reels launch the problem isa shorted driver on the interface board. If some reels don't spin, theproblem is only mechanical. Lubricate all the joints on the stop levers(the levers and mechanism for stopping the reels). All of the pivot partsof the stop levers should move freely.

Last Updated 11/24/2010

By John Robison

Almost every casino has its own gaming guide, and every casino gaming guide I've ever read recommends playing full coin at all times on all slot machines. Manyslot books make this same recommendation. The reason the books and guides give for always playing full coin is that you get the maximum long-term payback possible from a machine only when youplay full coin. This statement is true for some machines. For others, it isn't. Moreover concentrating only on long-term payback completely ignores the fact that you are putting more money atrisk when you play full coin than when you play short coin. Is the extra risk always balanced out by the increase in payback?

Are you really better off playing full coin at all times on all machines? I analyzed the programming on over 1,000 slot machines to formulate Robison's Rules for Playing Full Coin, whichfollow.
Play one coin at a time on Straight Multipliers.
A Straight Multiplier is a machine on which the payoffs for the winning combinations for the second coin are exactly twice those of the first coin, and the payoffs for the third coin are threetimes those of the first, etc. An example of a Straight Multiplier is a two-coin Double Diamond machine, which pays 800 coins for the jackpot when you play one coin, and 1,600 coins for thejackpot when you play two coins.

Playing more than one coin at a time on a Straight Multiplier is a waste of your bankroll. You’re not buying any new winning combinations, nor are you buying a bonus for a winningcombination.
The long-term payback of a Straight Multiplier is the same regardless of how many coins you play. Let’s say you’re going to play 1,000 spins on a one-dollar two-coin Double Diamond machine witha long-term payback of 95%. It makes more sense to expose only $1,000 to that 5% house edge, for an expected loss of $50, than $2,000, for an expected loss of $100.

Play one coin at a time on Bonus Multipliers - A Bonus Multiplier is just like a Straight Multiplier, only one or more combinations pay a bonus over the straight multiple. A three-coin DoubleDiamond machine, which pays 800, 1,600, and 2,500 coins for the jackpot when playing one, two, or three coins, respectively, is an example of a Bonus Multiplier. The straight multiple for thethree-coin jackpot is 2,400 coins, but this machine pays a 100-coin bonus for playing the third coin.

Even though Bonus Multipliers encourage you to play full coin to qualify for their juicy bonuses on some winning combinations (usually just the top jackpot), those combinations hit soinfrequently that even huge bonuses on them increase the long-term payback by very little.

Let’s look at an IGT Red, White and Blue machine. One payback program available for this machine pays a 2,800-coin bonus on the top jackpot for full-coin play. The long-term payback whenplaying one coin at a time is 91.757%, while the long-term payback when playing three coins at a time is 92.47%. The 0.713 percentage point increase in long-term payback does not make itworthwhile to play three coins at a time, unless you also cut back on the number of spins in such a way that you give the same amount of action. If you play at the same pace, you'll end upplaying three times as much money in the machine, but you won't get enough of an increase in payback with full-coin play to offset the increase in money you expose to the house edge.

Let’s compare the expected losses for the three styles of play: one coin at regular pace, three coins at regular pace and three coins at a slow (one-third of regular) pace. Let’s say we playthrough $1,500 at regular pace playing one coin at a time. The long-term payback is 91.757% when we play one coin at a time, so the house edge is 8.243%. When we play $1,500 against that houseedge, our expected loss is 8.243% of $1,500, or $123.65. If we play three coins at a time at the same pace, we decrease the house edge to 7.53%, but we triple our action to $4,500. Our expectedloss is $338.75. But if we can play three coins at a time at one-third pace, we play through only $1,500 at the full-coin house edge and have an expected loss of only $112.95.

It’s nearly impossible to maintain a slow pace when playing the slots. The sights and sounds of the casino are all designed to get you excited and to make you lose track of the passage of time.If you’re like me, you can keep a slow pace for a few minutes, but soon you’ll find yourself back at your regular pace and exposing too much of your bankroll. Because of the difficulty ofplaying at a slow pace, I recommend that players play one coin at a time on Bonus Multipliers.

I should mention one other thing about Bonus Multipliers. Many times the bonus is just a few hundred coins, but sometimes the bonus is huge, thousands of coins. If you can’t stand the thoughtof missing out on a big jackpot bonus because you played only one coin, do as I do and stay away from Bonus Multipliers with big bonuses.

A few years ago, I was at Bally’s Wild West casino playing one coin at a time on a bonus Multiplier that paid bonuses for full-coin play on multiple combinations. I hit one of the lower-payingbonus combinations. As I was waiting for my handpay, a passerby said that, “I bet you wish you had played full coin.”

I said, “If I had known I was going to hit on this spin, I would have played full coin.” Of course, I didn’t know that. Also, if I had been playing full coin all along, I would have run out ofsession money long before this spin. Instead, I chose to stretch my bankroll by playing one coin at a time and I was fairly sure that I was playing at a lower expected loss than playing fullcoin.

Play full coin on Buy-A-Pays - On Buy-A-Pays, additional coins buy additional winning combinations. The paytable on a Buy-A-Pay is displayed as a set of boxes, one box for each coin you canplay. The box labeled “1st Coin” shows all of the winning combinations that the first coin buys and how

much each combination pays. The box labeled “2nd Coin” shows all of the winning combinations and payouts that the second coin buys, and so on. If you play only one coin and a combination boughtby the second coin lands on the payline, you don’t win anything.
When you play additional coins per spin on a Buy-A-Pay, you activate additional winning combinations and you buy increased hit frequency and increased long-term payback. Sometimes the paybackon the first coin played in a Buy-A-Pay is very low—sometimes even as low as the regulations in a jurisdiction allow.

One of the payback programs available for a two-coin Sizzling 7s machine pays back 95.315% when played with one coin per spin, and 98.088% when played with two coins per spin. If you played1,000 spins, your expected loss would be 46.85 coins (4.685% of 1,000 coins) if you played one coin at a time, but only 38.24 coins (1.912% of 2,000 coins) if you played two coins at a time.

Although you're better off playing full coin on the Sizzling 7s payback program in the machine in my example above, there are other Sizzling 7s programs in which you are better off playing onlyone coin at a time. I can't guarantee that the increase in payback you buy with the additional coins will always outweigh the additional risk you have when playing more coins at a time. Butbecause that possibility exists, I recommend playing full coin on Buy-A-Pays.

There's another reason to play full coin on a Buy-A-Pay besides the mathematical one. It's an emotional reason. It can be very frustrating to have a winning combination land on the payline andnot get paid for it because you didn't bet enough coins. Playing full coin eliminates that potential frustration.

Play full coin on Hybrids - Some paytables are part Buy-A-Pay, part Multiplier. One additional coin buys new winning combinations and the other multiplies the payoffs on already activatedwinning combinations. I call these machines Hybrids for lack of a better name.

The split personality of the Hybrid presents us with a dilemma. We know it's not worth playing full coin on a Multiplier, but it frequently is worth playing full coin on a Buy-A-Pay. How do wereconcile this conflicting advice?

Let's look at one of the Blazing 7s payback programs. On this machine, the second coin is a multiplier for the bar combinations and the third coin buys the payoffs on the Sevens. This paybackprogram pays back 91.33% when played with one coin at a time, 95.10% when played with two coins at a time, and 97.18% when played with three coins at a time. Let's play 1,000 spins on thismachine. Your expected loss is 86.7 coins (8.67% of 1,000 coins) if you play one coin at a time, and 98 coins (4.90% of 2,000 coins) if you play two coins at a time. But your expected lossdrops to 84.6 coins (2.82% of 3,000 coins) if you play three coins at a time. You're better off playing full coin.

Some Hybrids have what I call a hidden Buy-A-Pay. On these machines you have to play full coin to be eligible to play a bonus game. When you have the opportunity to play a bonus game only whenyou play full coin, you must play full coin. There's no way to know how much the bonus game adds to the long-term payback and the increase could be enough to make playing full coin the bestbet.

You may remember a Hybrid with a hidden Buy-A-Pay slot machine from Anchor Gaming called Wheel of Gold. This machine is actually the progenitor of the Wheel of Fortune machine. You have to playthree coins on a Wheel of Gold to be eligible to spin the wheel in the top box on the machine. I looked at the payback of each coin played individually, and I discovered that the amounts youcould win when you spun the wheel pushed the payback of the third coin to well over 100%, 123.43% to be exact. The catch, of course, is that you have to play the first two coins, on which thehouse has a big edge, before you can play the third coin, on which you have the edge.

The long-term payback on this machine was 80% when you played one coin at a time and 94.99% when you played three coins at a time. Let's say you played 1,000 spins. At one coin per pull, yourexpected loss is 200 coins (20% of 1,000 coins). At three coins per pull, your expected loss is only 150 coins (5% of 3,000 coins).

I always play full coin on a Hybrid and slow down my pace, but you can play less than full coin. As long as you buy all the winning combinations, you'll be playing with the highest hitfrequency possible on that machine. Your payback however may not be as high as the machine can offer. Then again, even though the additional coins may buy increased payback, the increase inpayback is usually not as great as it can be on a pure Buy-a-Pay.

Play full coin on Multi-Lines - Don’t confuse this type of machine with the Multi-Line/Multi-Coin video slot. This type of machine limits you to a maximum bet of one coin per line. I don’tthink you will find many of them on casino floors in the future because the video slots give players much more betting flexibility, so Multi-Line players have switched to them.

My rule on a Multi-Line paytable is to let the player choose between playing one coin and playing full coin.

Dropping one coin at a time into a Multi-Line isn’t as bad as dropping one coin at a time into a Buy-a-Pay. The additional coins played in a Multi-Line machine buy increased hit frequency and,usually, only very small increases in average payback – just like on the Bonus Multiplier. The probability of hitting the jackpot is the same on all paylines, so even a large bonus for thejackpot on the last payline leads to only a small increase in payback. The extra coins don’t have the same positive effect on expected loss that they have on the Buy-A-Pay.

Let’s look at a typical payback program for a Multi-Line machine. One of the payback programs available for a five-line Double Diamond machine pays back 88.757% when played with one coin perspin and 92.516% when played with five coins per spin. For 1,000 spins, the expected loss rises from 112.43 coins (11.243% of 1,000 coins) for one-coin play to 369.25 (7.385% of 5,000 coins)for five-coin play.

Personally, I don’t like having winning combinations land on a payline that I haven’t activated, so I always play full coin when I play Multi-Line machines, even though it's not the right thingto do, mathematically speaking. Sometimes I put the math aside in favor of having more fun playing a machine.

Play one coin on each line on Multi-Coin/Multi-Line video slot machines - I never would have believed a few years ago that video slots would take over as much of the slot floor as they have.Some casinos today have half or more of their slot floors filled with video slots.

My rule for the number of coins to play on video slots is also to let the player choose between playing one coin at a time and one coin per line, though there's a strong economic argument forplaying only one coin at a time.

Additional coins played on a video slot usually buy only increased hit frequency, because each combination pays the same amount regardless of which payline it lands on. Playing one coin at atime stretches out your bankroll and your playing time. Playing one coin at a time, in addition, is less frustrating on a video slot than it is on a Multi-Line. The paylines on anAustralian-style slot are so complicated, it's difficult to tell when you have a winning combination land on a payline you didn't activate.

On the other hand, most video slots are low-denomination machines, so playing one coin on each line can be a smaller wager than playing full coin on a traditional three-reel slot. In this case,you can activate each payline, get a high hit frequency, and still risk less money per spin.

Furthermore, playing more than one coin per line is rarely a good bet, since the additional coins on each line usually just multiply the amount you win for each combination on each line. Withno bonus for additional coins, you're not buying an increase in payback, so there's no advantage to risking more of your bankroll.

Read the paytables on video slot machines very carefully. A game might require you to activate every payline to be eligible for a bonus game, so you’ll want to play all lines on those machines.Some games, in addition, advertise the huge payouts available when playing full coin on all paylines, but when you read the fine print, the payouts turn out to be straight multiples of thenumber of coins bet per line or the total number of coins bet, and therefore the extra coins are not worth betting.

Play full coin on all Progressives - Regardless of what type of Progressive the machine is – video, reel-spinning, standalone, wide-area -- always play full coin. When you play less than fullcoin on a Progressive, you’re just building the jackpot for someone else, with no chance of winning it yourself.

I want to end this discussion with a word about why I make the recommendations I do and about controlling your pace when you play.

Here's the general rule for when it makes mathematical sense to play full coin: Play 'n' coins per spin if the house edge when playing 'n' coins per spin is less than 1/n times the house edgewhen playing one coin per spin.

The house edge on the Wheel of Gold machine we looked at is 20% when you play one coin per spin and only 5.01% when you play three coins per spin. That's less than 1/3 times 20%. You can play this machine with full coin at the same pace as someone playing one coin at a time and still win more in the long run.

Now let's look at the house edge on the RWB Bonus Multiplier above. The house edge at one coin per spin is 8.243% and the house edge at three coins per spin is 7.53%, well above 2.748%, thepercentage at which the expected loss for the one-coin player equals the expected loss for the full-coin player. The machine will hammer the full-coin player if he plays at the same paceas the one-coin player.

The machine will win about three times as much money from the full-coin player, even though the full-coin player is playing at a lower house edge. The problem is that the house edge isn'tcut low enough for the full-coin player to play at full speed. The full-coin player gets killed because he has triple the action of the one-coin player, but his house edge isn't lowerthan one-third the one-coin player's house edge.

If the full-coin player, on the other hand, can slow down so he plays one spin for every three the one-coin player plays, he will give the same amount of action as the one-coin player, but atthe full-coin's lower house edge. It's true that the full-coin player will experience greater volatility because he has fewer spins (Remember the confidence intervals?), but in the longrun the slow-playing full-coin player will lose less than the full-speed one-coin player.

The problem in this scenario is in playing slowly. Controlling your pace when you play is not as easy as it sounds. The casinos want you to play fast because they have the edge onevery spin. The more spins slot players play per hour, the more money the casinos make.

Try it some time. Note the time that you start playing a slot. Now play it for a few minutes and keep track of the number of spins you play. If the slot club uses a countdownor an open formula for cashback, you can use the number of points or dollars you earned to tell you how many spins you played. Otherwise, you'll just have to count. When you'refinished playing, note the length of time you played and the number of spins you played.

Slot Coin In

Now try to play one-third the number of spins in the same length of time. Note your starting time and start playing. When you've finished playing the appropriate number of spins,note the elapsed time. It's shorter than the elapsed time in the first trial, right?

It's not easy to cut your pace down to one-half or one-third of your usual pace. Because few people can effectively control their pace when they play, I recommend playing one coin at atime on some machines even though you will be playing at a higher house edge. My goal is to limit your losses. There are two components in your expected loss: the house edge and howmuch money you expose to it. Many times, the best way to cut your expected loss is to focus on the second variable in the equation and cut the amount of money you expose to the houseedge.

My Bally Slot Machine Will Not Accept Coins

John Robison is the author of 'The Slot Expert's Guide
to Playing Slots.' His website iswww.slotexpert.com