Bally E Series Repair Tips

Repair Tips for Reel Readers

How to test and what to look for when doing your own repairs

When one of these goes bad you may see an error that would be 4x or 7x where x indicates the reel position, i.e. a 43 error code would indicate the reel reader on the third reel.

What is described below is for testing the reel reader card using this home built tester. The tester provides both a 50 volt source or a 5 volt source (switch selectable).

After describing this procedure I will tell you how to test the cards with out having to have a 50 volt source.

Tests both 5 volt and 50 volt reel reader cards

I designed and built a tester to make troubleshooting easier. I test the card and all of the photo-transistors
first, then I split the two halves of the card, one for cleaning but also so that I can use a dental tool, poking
it into the tiny opening to push the photo-transistor or IR Emitter back up and out of the small square opening. The photo-transistor/Emitter should be at something close to a 45 degree angle.

Once the bad components are pushed out of the way, I use my soldering iron to melt the solder on both leads at the same time while grasping the upper portion of the optic. It comes off very easily. Once removed use solder wick to remove the excess solder. You want to do this so that when you put in the new device the leads will be nearly flat on the PC board.

Replace the defective components and quickly tack one side, allow the solder to cool and then solder the other side. Once the other side has cooled you can go back and firmly solder the lead that was previously tacked. Reassemble and then retest to make sure that the optics are working properly. Tapping the top of the card lightly with the handle of a screw driver will show any intermittent connections.

The one question that may come up is what constitutes a bad device. Since the reader cards supply signals to TTL logic devices then we can use standard logic levels of 2.0 volts as a high and .8 volts as a low. When measuring the output of the photo transistor, if the voltage is less than 2.0 volts, while unblocked or higher than 0.8 volts when blocked then that photo-transistor (or emitter) is defective.

In the cards that I have repaired I typically see voltages of greater than 4 volts unblocked and .01 volts blocked for the 50 volt reader cards, 5 volt reader cards the unblocked voltage is 3.14 and the blocked voltage 0.2.
Test all of the emitters and photo-transistors first, the replace all defective ones. I make it a habit to clean the bulbs with alcohol on the 50 volt cards so that as much light as possible gets to the photo-transistor.


Testing reel readers without having a 50 volt source.

The 50 volt supply is only used to power the incandescent bulbs. They are in series along with the 470 ohm resistor. Each bulb requires 5 volts to operate properly.

You need a few basic items, a Volt/Ohm meter (DVM) , a 47K resistor, a light source (flashlight) and some clip leads and a 5 volt DC power supply

Split the cards by removing the 2 screws and lay the small card off to the side

If you lay the card flat on its back with the mounting bracket to the left then the pins at the bottom will number 1 through 16 from right to left
Measure the resistance between pin 16 and 14, Pin 16 is Vcc and 14 is Ground you should have a reading  a bit above 500 ohms, indicating that the 470 ohm 2 W  resistor and all of the bulbs are OK. If not in this range then you will have to remove  the tape covering the backs of the bulbs and then measure resistance across each bulb individually. Remember the bulbs are wired in series like the old Christmas tree light strings.

Assuming that the bulbs and resistor are OK. Attach the ground lead of the volt meter and one end of the resistor to pin 14 (pairs 13/14)
 of the card. Connect the other end of the resistor and the positive lead of the volt meter to pin 11.

Now using the 5 volt supply, apply 5 volts to pin 1 of the card and read the voltage, shine the light into the small (tiny) hole that is for Q1, voltage should be some where around 4.7 volts with the light on and some where less than 0.2 volts with the light off. Just keep in mind that ambient light might cause the light off reading to be higher. The acceptable voltage ranges need to be within the acceptable ranges used in ‘Logic” circuits so a logic high you need 2 volts or more and a logic low 0.8 volts or less.

You may find that if you have these readings, a Q-tip dipped into alcohol can be used to clean the top of the photo-transistor by pushing the Q-tip into the hole and then twisting the Q-tip. I routinely clean these as well as to clean the bulbs.

Repeat this process for each of the following pins 1, 3, 5, 7, 9

Other than pin 11, all of the other pins are in pairs

Pins 1 & 2 Collector of Q1
Pins 3 & 4 Collector of Q2
Pins 5 & 6 Collector of Q3
Pins 7 & 8 Collector of Q4
Pins 9 & 10 Collector of Q5

Pin 11, Common emitter
Pin 12 Missing (pin is cut off)

Pins 13 & 14 Ground
Pins 15 & 16 Vcc
This process is not nearly as quick or accurate as using the tester but should allow you to test each of the cards.

The 5 volt card testing process is not much different other than it is not necessary to split the cards and you need a 3K resistor instead of a 47K resistor.

Apply the 5 volts across pins 16 and 14 and then measure the voltage on the associated
pin pairs.
In this case the 3K resistor attached to pin 14 and pin 11 biases  another transistor’s base (Q6),  pulling it low so that it will turn on the IR Emitters. Remember to block the light for each IR  emitter to see the photo-transistor transition to a low state.

Testing results for the 5 volt cards readers you  will not read  anywhere near 4.7 volts,  they will be closer 3.0 volts for a high and about 0.2 volts for a low

Repair Tips for Power Supply

I have noticed that the schematic for the Bally E1000/E2000 power supplies list expected voltages, but, what does that mean?

I have a couple of these power supplies so I decided to do some testing to see what voltages were obtained under certain circumstances.

If you apply 12 VAC across pins 1 and 10 of the board J1 connector,you should be able  to measure the voltages on the test points (+UR, ZC and 5V)

These voltage readings are based on a supply that has no load (nothing else connected)

UR = 15.96 VDC
ZC = 10.07 VDC
5v = 5.0 4VDC

One might think something is wrong because both UR and ZC are higher than the schematic states. However with no current we would expect to find the voltages higher, what matters is the voltage under load conditions.

The LM340-T5 Regulator has a maximum current output of 1 amp so using ohms law we know the voltage is 5 volts and the current is 1 Amp, Resistance can be calculated using the formula R=V/I (R=5/1) so R=5Ω, Now that we know what to use, we can figure out the wattage, this is rather simple, Watts = Amps x Volts so in this case we have 5 volts, 1 Amp so need 5 Watts. For testing I use a  couple of 5Ω 5W resistors , actually, I use 20 Watt resistors to keep from burning my fingers.  Anything smaller than 5W will burn and smoke is bad. The load resistors are placed across pins 13 and 20 of the J1 connector

To test the power supply drawing .5 amps we place 2, 5Ω  resistors in series for a total of 10 Ω. With a 10 Ω load, drawing .5 amps  these readings are fairly typical of what you should expect to see

UR = 12.16 VDC
ZC= 8.83 VDC
5v = 5.01 VDC

The final test is to test at full load, drawing 1 amp of current by removing one of the 5 ohm resistors so that only 5 ohms appears across pins 13 and 20 of J1, the readings you should expect to see would be.

UR = 7.57 VDC
ZC= 9.6 VDC
5v = 4.98 VDC

It would appear that the voltages shown on the schematic are voltages when the power
supply is measured with a full load.

I also recommend that when repairing these power supplies to remove the heat sinks from the bridge rectifier (BR1) and the 5 volt regulator (Q1). Clean off the old thermal heat sink compound and add new compound so that the heat transfer is more even. This will allow for maximum cooling.

The minimum voltage to expect from the LM340-T5 is 4.75 volts, if  less than this then it is better to spend a couple of dollars and replace it.

Sometimes you will find that you have no voltage. In this case you want to check the 4 diodes and if the voltage seems to be half of what you expect then check the solder connections on the bottom side of the diodes. These will become bad because of heat. Other causes of no voltage is an open diode in the Bridge Rectifier (BR1).

I would recommend to anyone doing any type of repair work to invest in an ESR Meter. ESR means Equivalent Series Resistance and a high ESR can have adverse actions to your circuit. I have had several of these power supplies where despite changing the diodes, bridge rectifier and voltage regulator the output voltage was still below the regulators specified voltage of 4.75 volts @1 amp. These problems were resolved using my ESR meter and the discovery of the large 11,000 ufd capacitor having a high ESR value.


Can’t run Tests

I have seen many complaints of not being able to run the tests or clear errors on these E Series machines. If you have a light tower the WHITE light should be illuminated before the tests or resets can be done. This does not mean that a burnt out bulb will prevent this but only serves as a quick indication that you should be able to run tests or clear error codes. If you find that you are unable to run the tests or reset the machine, check the cherry switch behind the door hinges. If this switch goes bad it will signal the MPU board that the door is closed. Many owners of these E machines will bypass the door switch however the cherry switch must be operational

RAM Tester

NeoLoch 5101 Ram Tester

Since many of the problems with the E Series slot machine are related to RAM failures I thought it would be a good idea to have one hanging around in my shop. I searched the web and located a guy that had developed a tester for testing the 6264 RAM chips. I sent him an email asking if this might be easily converted to test the 5101 RAM chip used in the Bally E Series slot machines and a large number of Bally Pinball machines. As it turned out he did not have a problem in making this modification as an ‘Engineering Change’ for me. My tester only tests the 5101 RAM chips, but NeoLoch Sales has since altered the design so that it will now test 5101, 6116, 21C14 and 9114 RAM Chips. It also will run on a 5, 12 volt power supplies or from a 9 volt battery.

For further information please visit his website NeoLoc the page will open in a new window. This tester is now obsolete and has been replaced by a newer more versatile version

If you have some electronic design work that you need to get done contact David, he is easy to work with and offers reasonable prices.


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