Bally 6803

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1 Introduction

A look inside the backbox of "Eight Ball Champ", the first Bally 6803 game. Eight Ball Champ was designed to use either the Squawk & Talk sound board or the Cheap Squeak sound board. The game also used -17/-35 era 6/7 digit displays located on the lamp insert board.

Inside the backbox of "Strange Science", which used the Turbo Cheap Squeak sound board and the "new" 14 digit plasma displays.

The Bally 6803 game system, and the games themselves, were developed with extreme cost consciousness in mind. Bally used particle board cabinets with minimal artwork, backglasses illuminated by a single 115VAC light bulb, cheaper materials and short cut techniques during these years of game development. Wire harnesses, although specified with certain wire colors in the schematics, may in fact be constructed from wire of other colors. The tried and true method of ensuring that the colors of the wires going into a connector match the colors of the wires going out of a connector isn't always useful in Bally 6803 games. In this case, Bally's cost consciousness can cause game enthusiasts all these years later quite a bit of confusion. Still, many of these games continue to be enjoyed by hobbyists now and will be for years to come.

As seen in these pictures, the backbox configuration generally consisted of the game transformer, a power conditioning board (lower right), a sound board (upper left), and a new 6803 processor based MPU board that integrated all game control functions previously found on on Bally -17/-35 MPU boards, lamp driver boards, and solenoid driver boards, onto a single MPU board.

2 Games

Game Title	Game Number	Sound	Displays	Transformer	Keypad Used	Notes
Eight Ball Champ	0B38	Squawk & Talk	4 7-Digit / 1 6-Digit		Yes
Beat the Clock	0C70	Squawk & Talk	4 7-Digit / 1 6-Digit		Yes
Lady Luck	0E34	Cheap Squeak	4 7-Digit / 1 6-Digit		Yes
Motordome	0E14	T. C. S.	2 "Special" 14-Alphnumeric		Yes
Black Belt	0E52	T. C. S.	2 "Special" 14-Alphnumeric		Yes
Special Force	0E47	Sounds Deluxe	2 "Special" 14-Alphnumeric		Yes
Strange Science	0E35	T. C. S.	2 "Special" 14-Alphnumeric		Yes
City Slicker	0E79	T. C. S.	2 "Special" 14-Alphnumeric		Yes
Hardbody	0E94	T. C. S.	2 "Special" 14-Alphnumeric		Yes
Party Animal	0H01	Sounds Deluxe	2 "Special" 14-Alphnumeric		Yes
Heavy Metal Meltdown	0H03	Sounds Deluxe	2 "Special" 14-Alphnumeric		Yes
Dungeons & Dragons	0H06	Sounds Deluxe	2 "Special" 14-Alphnumeric		Yes
Escape from the Lost World	0H05	Sounds Deluxe	2 "Special" 14-Alphnumeric		No
Blackwater 100	0H07	Sounds Deluxe	2 "Special" 14-Alphnumeric		No
Truck Stop	2001	D-11581-2001	2 "Special" 14-Alphnumeric		No	Uses a sound interface board to process signals for sound board
Atlantis	2006	D-11581-2006	2 "Special" 14-Alphnumeric	5610-12136-00 or 5610-12393-00	No	Uses a sound interface board to process signals for sound board

Game model numbers provided by the Internet Pinball Database - http://www.ipdb.org

NOTE: Not to be mistaken with the video game Turbo Cheap Squeak, which does not have on board amplification, the pinball Turbo Cheap Squeak is referred to as the T. C. S. sound board.

3 Documentation

3.1 Manuals & Schematics

An example "short" female connector housing, this one on an Eight Ball Champ. There is no guarantee that all connectors to this MPU connector for other games or your game is a short connector. Fortunately, at least the "key" pins can be relied upon for correct connector placement.

The owner's manual is a handy resource to have for game settings and audit information. Schematics for each game are essential in tracing down connections to lamps, switches, and solenoids.

Note: The wire colors specified in the manual will not always match the actual wire colors used, sometimes even in the same circuit as the circuit crosses a male/female molex connector. And, the female housings used to connect wire harnesses to the MPU (for instance) might be longer or even shorter than the pin specification in the manual (see image at left).

3.2 Parts Catalogs

Parts catalogs can also be useful, which include part numbers (helpful for purchasing parts online), exploded views of assemblies (helpful to see how the assemblies are put together), and board layouts & parts lists, and diagrams for controlled lamp, solenoid, and rubber locations. Online copies of Bally parts catalogs can be found on Planetary Pinball.

Catalog	Cover	Source	Games	Notes
Bally/Midway 1986 Parts Catalog		Viewer	Beat the Clock, Hot Shotz, Eight Ball Champ, Lady Luck, Motordome, Black Belt, Karate Fight, Special Force, Strange Science	Exploded views and parts lists of common assemblies, such as flippers, kickers, drop targets, slingshots, and more. Cabinet parts included. Circuit board layouts & parts lists. No game-specific information or playfield diagrams included.
Bally Pinball Game Playfield Parts Guide - 1987		Viewer	Motordome, Black Belt, Special Force, Strange Science, City Slicker, Hardbody, Party Animal, Heavy Metal Meltdown	Playfield diagrams (both of the top side and bottom side) listing parts and assemblies. However, rubber placement and switch/solenoid designations are not included.
Bally 1987 Pinball Pinball Game Common Assemblies		Viewer	Motordome, Black Belt, Special Force, Strange Science, City Slicker, Hardbody, Party Animal, Heavy Metal Meltdown	Exploded views and parts lists of common assemblies, such as flippers, kickers, drop targets, slingshots, and more. Cabinet parts and display board parts are also listed.

3.3 Service Bulletins

Supplementary service bulletin books were released, which included service bulletins that detailed any problems or issues with games that were discovered after they were released.

Manufacturer	Version	Cover	Source	Games	Notes
Bally	Service Bulletin Book, 1987		PDF	Cybernaut, Eight Ball Champ, Motordome, Black Belt, Strange Science, Hardbody	Also contains some later classic Bally games (-35 MPU)
Bally	Service Bulletin Book, 1988		PDF	Beat the Clock, Motordome, Black Belt, Strange Science, Hardbody, Party Animal, Heavy Metal

4 Technical Info

4.1 MPU Board

Bally 6803 MPU Board

The schematics for the Bally 6803 MPU Board can be found here.

The Bally 6803 MPU incorporates all of the function of it's predecessors, the -17 and -35 MPUs, along with lamp and solenoid drive circuitry. The MPU is responsible for driving all game features other than sound, which is handled by one of several sound boards used in the 6803 game system run.

Architecturally, the board is similar to it's predecessors but employs the 6803 microprocessor along with two 6821 Peripheral Interface Adapters. It also contains what is essentially the entire lamp board circuitry along the left side of the board, including the familiar 4514 demultiplexers, 2N5064 SCRs (2N5060s from the factory) and MCR-106 SCRs (silicon controlled rectifiers). Along the top of the MPU board, the solenoid driver circuitry of the older Bally Regulator/Solenoid Driver Board has been incorporated, including the typical 74LS154 4-to-16 decoder, CA3081 transistor arrays, and TIP-102 transistors. A "cube" relay, located in the upper right corner of the MPU, is used to complete the power circuit for the flippers and is energized only when a game is in play.

A 6116 static RAM is battery backed for non-volatile memory storage. Fortunately, the battery can be clipped off the board and a simple 6116 NVRAM module installed in place of the 6116 static RAM. No other modifications are necessary to accomplish this and fortunately, the 6116 position is already socketed. Highly recommended!

4.1.1 CPU Board ROM Info and Jumper Settings

Jumpers for this board gives several EPROM selections.

2732 EPROMs at U2/U3: Jumpers JW1,3,5=in, JW2,4,6=out
2764 EPROMs at U2/U3: Jumpers JW5=in, JW1,2,3,4,6=out
27128 EPROMs at U2/U3: Jumpers JW2,4,6=in, JW1,3,5=out

Jumper JW7 should always be out.

Jumper JW8 in: PB14 drives General Purpose driver circuit 1 (J9 pin 9 via Q9)
Jumper JW9 in: PB14 drives "light" switch drive 1 (J4 pin 1)
Jumper JW10 in: PB15 drives General Purpose driver circuit 2 (J7 pin 4 and/or J6 pin 7 via Q10)
Jumper JW11 in: PB15 drives "light" switch drive 2 (J2 pin 19)

Game	U2	U3	Jumpers
Eight Ball Champ	Not Used	0B38-00803-0005	2, 4, 6, 8, 10
Beat the Clock*	Not Used	0C70-00803-0005	2, 4, 6, 9, 10
Lady Luck	Not Used	0E34-00803-0005	2, 4, 6, 8, 10
Motor Dome	E14A-42AAE-BX40	E14A-42AAE-CX4D	2, 4, 6, 8, 10
Black Belt	0E52-00803-0001	0E52-00803-0002	2, 4, 6, 9, 10
Special Force	0E47-00803-0004	0E47-00803-0005	2, 4, 6, 9, 10
Strange Science	0E35-00803-0001	0E35-00803-0002	2, 4, 6, 9, 10
City Slicker	0E79-00803-0002	0E79-00803-0003	2, 4, 6, 9, 10
Hard Body	E94A-12601-0000	E94A-12602-0000	2, 4, 6, 9, 10
Party Animal	H01A-12601-0000	H01A-12602-0000	2, 4, 6, 9, 10
Heavy Metal Meltdown	H03A-12601-0000	H03A-12602-0000	2, 4, 6, 8*, 10
Dungeons & Dragons	H06A-12601-0000	H06A-12602-0000	2, 4, 6, 9, 10
Escape from the Lost World	H05A-12601-0000	H05A-12602-0000	2, 4, 6, 8, 10
Blackwater 100	H07A-12601-0000	H07A-12602-0000	2, 4, 6, 9, 10
Truck Stop	H08A-12601-0000	H08A-12602-0000	2, 4, 6, 9, 10
Atlantis	2006-12601-0000	2006-12602-0000	2, 4, 6, 9, 10

As can be seen above, jumpers 2, 4, 6, and 10 are always IN, along with EITHER jumper 8 or 9.

*Note: Regarding "Heavy Metal Meltdown", while the game manual states JW9 should be in, that is an error. JW8 should be in, JW9 out.
*Note: Regarding "Beat the Clock", the game manual may state W8 in, W9 out. However, there was a service bulletin after the game was released stating the opposite.

4.1.2 CPU Board Power Up Sequence

The follwing is an abbreviated self-test routine for the 6803 Control Board

1st flash - (U1) Determine if the internal RAM is good. (6803)
2nd flash - (U2) Checks to see if the program ROM is good (27128)
3rd flash - (U3) Checks to see if the program ROM is good (27128)
4th flash - (U4) Checks to see if the external CMOS RAM is good (6116)
5th flash - (U8) Tests PIA-0 (6821) Note: See the section MPU can't get past 5th flash, below
6th flash - (U7) Tests PIA-1 (6821)
7th flash - (U1) Checks the internal display interrupt generator (6803)
8th flash - (U12 & U8) Verifies operation of the phase B switched illumination voltage.
NOTE: F5 fuse on the Power Module provides the phase B signal to the Control Board.
(U12, 14584) (U8, 6821)
9th flash - (U1, U11 & U12) Verifies operation of the phase A switched illumination voltage.
NOTE: F4 fuse on the Power Module provides the phase A signal to the Control Board.
(U1, 6803) (U11, 4011) (U12, 14584)

4.2 Power Supply Board

The power supply board from a 6803 based Bally game.

Solder joints on the single sided board are subject to fracture.

The schematics for the Bally 6803 Power Supply Module can be found here.

The Bally 6803 game system power supply board provides all of the voltages necessary to operate the game. Solder joints, as shown on the right are subject to fracture on the power supply board, especially since it's a single sided board. Reflowing these solder joints will solve many power problems.

4.3 Sound Boards

4.3.1 Squawk & Talk

Bally Squawk & Talk Sound Board

The Bally Squawk and Talk board, so widely used in -35 MPU games, was also used in several 6803 games like "8 Ball Champ" for instance.

More information regarding the Bally Squawk and Talk board and debugging it can be found here.

4.3.2 Cheap Squeak Sound Board

Bally Cheap Squeak Sound Board A080-91603-XXXX or Midway P/N M-051-00114-XXXX

The Cheap Squeak was designed as a lesser expensive sound board. It only utilizes a 6803 microprocessor, which allows it to function without 6821 PIAs and external RAM memory. This sound board is only capable of simple tones and sounds, but not speech. Although the Cheap Squeak is used in a handful of -35 based Bally games, Lady Luck is the only 6803 based game which uses it.

At power up, the Cheap Squeak's LED will flicker briefly, then flash, flash again, then turn on and stay on. Once the LED stays on, it seems to turn itself off for certain sounds, and then turn back on. Likewise, it appears to idle with the LED on, when no sounds are playing. The LED May turn on and off when sounds are playing or idle, but this is not always the case.

With Lady Luck, upon pressing the self test button (SW1), the sound board will play an explosion type noise. The board will then reboot itself.

Board Theory of Operations
The 6803 (U1) microprocessor multiplexes A0-A7 with D0-D7, calling those signals AD0-AD7. The processor fetches information from the sound ROMs (both code to execute and sound clips) by placing address information on AD0-AD7 and strobing the processor's AS (address strobe) signal to the 74LS373 (U2), thereby latching the lower 8 bits of the address bus in the LS373. A8-A15 are used along with jumpers JW1 through JW12, to implement a memory mapped I/O scheme to address the 2 sound ROMs which can be 2532s, 2732s, or 2764s. A14 and A15 control the 74LS10 (a triple 3-input nand gate) to assert device selects to the ROMs.

Note that the processor does not use the traditional R/W signal as it never "writes" to memory. Besides placing instruction address and data on the address and data busses, the processor reads sound selects via P20-P24 and writes sound data to the DAC via P10-P17. Think of these lines as PA1-PA7 of a 6821 or 6532.

The 6803 is initialized by the MPU at power up into 6803 mode N. Once initialized and running, the sound ROM code running in the 6803 accepts sound signal commands and merely reads pre-formatted sound "clips" from the sound ROMs and then writes the data to the ZN429 (U6) digital-to-analog converter (DAC) 8 bits at a time. The DAC converts the digital data to an analog level which is presented to the amplifiers for output to the speaker(s).

The board creates 5VDC on board by regulating 12VDC down to 5VDC. Unregulated 12VDC enters the board at J1-10. It is filtered by C8, C9, and C10. The inductor at L1 smooths the voltage somewhat. D6 (VR332, equivalent to a 1N5402), D7, and D8 drop the voltage by .5 - .7 volts (normal voltage drop across a diode). The 7805 at U9 further regulates the voltage down to 5VDC which can be measured at TP2 (TP3 is ground).

This 5VDC is used as a reference voltage by the amplifiers as well as to power the TTL logic ICs. The ZN429 DAC also uses this 5VDC as a voltage reference. To prevent the sound volume from fluctuating over the range of operating temperatures, the reference voltage is held constant by a "voltage divider biasing circuit" comprised of resistors at R22, R23, and R24, and a 2N5305 NPN transistor at Q7. This reference voltage is presented at pin 5 of the DAC.

Test Points

• TP1 should measure about 11VDC.
• TP2 is 5VDC.
• TP3 is ground.
• TP4 is the clock signal, provided externally by the 6803 for the purpose of synchronizing address and data read cycles.
• TP5 is the reset signal, which is also present on pin 6 of the 6803.
  

Bally Cheap Squeak Sound Board with Jumpers Highlighted

Jumpers JW2, JW4, JW7, JW10, and JW11 should be installed when U3 EPROM is installed for Lady Luck.

4.3.3 Turbo Cheap Squeak (T.C.S.)

The Bally Turbo Cheap Squeak (T.C.S.) Sound Board. This is the -C000 version of the board. Note that the headers, which are normally individual pins soldered directly to the board, have been replaced on this board. The test switch is also broken on this board.

The -E000 version of the board. Note the use of a PAL (U3) to replace a small number of logic chips.

The schematics for the Turbo Cheap Squeak sound board can be found here.

The Turbo Cheap Squeak sound board was used on games like Strange Science and Motordome. The sounds it can produce are pretty basic. Do not confuse this board with the Bally video game sound board with the same name. The two boards are entirely different.

The board features a 68B09EP processor, a 6821 PIA, 16K of static ram, and a 256kb or 512kb ROM. It interfaces to the MPU similarly to the Bally Squawk and Talk board. Volume is controlled by the 1K pot at VR1 in addition to the volume pot on the coin door of the game, which is wired backwards (turn the pot on the coin door counter-clockwise to increase the volume). Note that a 68B09EP chip MUST be installed since the chip relies on an external clock. A standard 6809 will not boot the board.

Note that the board is marked "T.C.S. FOR PINBALL". Some Bally/Midway video games also use a Turbo Cheap Squeak sound board. The T.C.S. sound boards used for video games and pinball are not 1-to-1 compatible between one another.

There are two revision designations of the T.C.S. sound board, -C000 and -E000. The -C000 board uses a 74LS02 (U3) and a 74LS139 (U4), while the -E000 board has a single 16L8A PAL programmable PAL chip (U3) in the vicinity of these two chips. The -C000 boards all use 27256 ROMs, while the -E000 boards use 27512 ROMs.

Motordome, Black Belt/Karate Kick, and Strange Science shipped with the T.C.S -C000 board.
City Slicker and Hardbody shipped with the T.C.S -E000 board.

Normal boot up LED flashes provide the following indications:

• 1st Flash - Determines if the external ROM (U7) is good.
• 2nd Flash - Checks if the external RAM (U6) is good.
• 3rd Flash - Checks the 6821 PIA (U8).

For bench testing, +12VDC, ground and an external speaker are the only connections necessary. Tie all 4 grounds together (pins 12-15).

Note: During bench testing, a good board will function differently, depending on which game software is installed. Specifically;

Strange Science: 3 quick LED flashes at power up. Pressing the test button produces a bong. No additional LED flashes.
Black Belt: 2 quick flashes, a pause of 5-6 seconds, then the 3rd flash. Pressing the test button produces no sound, but will re-boot the sound board. The LED will then flash 3 times accordingly, like at initial power-up.

-E000 Backward Compatibility
The -E000 board is backward compatible, and can use a 256kb ROM, by configuring JW9/JW10 as follows:

• 27256 ROMs...JW9 - out, JW10 in
• 27512 ROMs...JW9 - in, JW10 out

The PAL at U3 on the -E000 board must be configured via JW11 as follows:

• For Motordome, Black Belt Karate Kick, and Strange Science, JW11 should be out, which runs the board in -C000 mode.
• For Hardbody and City Slickers, JW11 should be in, which runs the board in -E000 mode.

If these jumpers are not set correctly, the diagnostic LED will not flash.

Note: Jumper JW12 has no function. It may have been intended for additional capability that was never implemented.

4.3.4 Sounds Deluxe

Bally Sounds Deluxe Sound Board

Bally Sounds Deluxe Sound Board Schematics

The schematics for the Bally Sounds Deluxe Board can be found here.

Note: that the board pictured at left still has the electrolytic capacitor below the PAL chip. This capacitor should be removed to prevent damage to the DAC on the board.

A YouTube video of this sound board with Special Force ROMs being tested with the onboard diagnostic button can be found here.

4.3.5 Williams D-11581 Sound Board and C-12417 Sound Interface Board

Williams D-11581 sound board as found in Truck Stop and Atlantis, component side

C-12417 sound interface board as found in Truck Stop and Atlantis

Williams D-11581 sound board as found in Truck Stop and Atlantis, solder side.

As the Bally pinball company was being absorbed by Williams, a crossover time period resulted in the need to drive a Williams D-11581 sound board from a Bally 6803 MPU for both Truck Stop and Atlantis. Since the Bally 6803 system had never used -12VDC in any prior sound board, a special "interface" board was created that derives -12VDC from the available +14VDC via a LT1054 voltage regulator. This small board, pictured at right, also relays sound select and strobe signals from the 6803 MPU to the D-11581 sound board. A reset signal is also derived from the strobe signal via a 74LS74 Quad-D Flip-Flop, and sent back to the MPU board. The purpose of this "reset" signal as it is labeled in the schematics is probably not the typical processor reset signal. It is probably a simple indication that the sound signal has been received by the sound subsystem.

Note: The additional green jumper, 1Kohm resistor, and 22uf tantalum capacitor added to the solder side of the Atlantis D-11581 sound board pictured at left were removed and the board worked perfectly. It is not known why these modifications were introduced originally.

4.4 Trough Optos

4 Opto Trough Transmitter Board

4 Opto Trough Receiver Board

Starting with Dungeons & Dragons, some 6803 series games used infared (IR) opto sensors for the trough switches. The more common transmitter and receiver boards used a total of 4 opto sensors.

Escape from the Lost World used a dual opto sensor transmitter and receiver (shown below).

Blackwater 100 and Truck Stop used a 4 sensor board.

Atlantis did not use an opto sensor board, but instead had a trough assembly with switches very much like Williams System 11 games.

The transmitter board consists of Motorola MLED930 IR emitters and current limiting resistors (68 ohm 1/2 watt). The receiver board consists Motorola MRD370 IR light detectors, 2N3904 transistors, and 390 Kohm 1/4 watt resistors. The transmitter board is powered by +5VDC. Both the opto sensors and receivers are obsolete and have become quite pricey.

4 Opto Trough Transmitter Board

The two opto transmitter and receiver boards used on "Escape from the Lost World".

4.5 Accessing Bookkeeping, Settings, and Diagnostics

6803 coin door test button

The single black button shown on the right side of the picture (just above the volume pot) causes the game to enter audits/diagnostics mode. All subsequent control of the game audits/diagnostics is done using the keypad (see below) in most cases. Some of the later 6803 games, such as Escape from the Lost World and Blackwater 100 abandoned the use of the keypad. Flipper buttons, auxiliary buttons (located below the flipper buttons) in combination with the start button are used to advance through bookkeeping, settings, and diagnostics.

On some earlier games, if the game detects a "stuck switch", it will make a hugely annoying sound until the stuck switch condition is corrected. Advice: turn the volume down. Later games would advance to attract mode regardless of stuck / closed switches.

4.5.1 6803 Keypad and Built-In Tests

The "beloved" 6803 keypad

As easy as "A, B, C"... Bally attemped to improve the operator's interface to the game system with this poorly constructed keypad. The keypad can be used to set free play, what kind of sounds are desired, balls per game, etc. See your game manual for game specific information.

The settings can be rather counter intuitive. For instance, setting 42 (or register 42 as it's called in the manual) allows the operator to set the game to free play by entering "65".

Setting 27 allows the operator to configure the game sound style. Usually, you'll want this set to "3" which causes a "noise" effect when scoring occurs and enables background sound.

Using the keypad to enter the following values begins the associated test. What could be more logical? ;-)

90 - Lamp Test
91 - Display Test
92 - Solenoid Test
93 - Sound Test
94 - Stuck Switch Test

4.6 Dual Display Boards

Dual Display (2x 7-digits)

Insted of the 4 single score displays, Bally started to use the Dual Display Module. These are actualy 2x 7-digits displays into one glass. Also the displays went from numeric to alpha-numeric, making it possible to display text (letters). Now they can display instruction for the game and you can enter your initials for an achieved high score.

The main noticeable difference for the H000 version is the presence of the RM1 array.

There are two versions schematics available.
The schematics for the A084-91851-F000 can be found here.
The schematics for the A084-91851-H000 can be found here.

5 Problems and Fixes

5.1 Transformer Voltage Selection

Voltage Selection Plug for Bally 6803 Games, set to 115VAC. Image Courtesy of Chris Hibler.

Jumper to configure for 115V and 120V power. Image Courtesy of Sascha Voskuil.

The image at left depicts the voltage selection plug in the backbox of an Eight Ball Champ.

This plug is jumpered for 115VAC.

The blue and yellow wires are AC power in.
The orange jumper wires are placed in specific pin locations to select the appropriate voltage.

Voltage Selection Plug for Bally 6803 Games, set for 220VAC. Image Courtesy of Jaime Glenn, augmented by Sascha Voskuil.

The voltage selection plug pictured at left is jumpered for 220VAC.

5.2 Power Problems

The power supply board from a 6803 based Bally game.

Solder joints on the single sided board are subject to fracture.

The Bally 6803 game system power supply board provides all of the voltages necessary to operate the game.

The 190VDC display voltage is derived from 170VAC input via the same circuitry as was used by the prior generation regulator/solenoid driver board. All of the same practices apply to this board including replacing the 25Kohm trim pot. The power supply shown at left has had the failed 160uf/350V high voltage filter cap replaced.

The board shown at left still has the original 3/4 inch fuse in the high voltage section. When necessary, it's easy and advised to modify the board to accept the more common 1.25 inch fuses as shown here.

Solder joints, as shown on the right are subject to fracture on the power supply board, especially since it's a single sided board. Reflowing these solder joints will solve many power problems and is highly recommended.

The 5VDC logic voltage is derived from 9.4VAC input, again using similar circuitry to the prior generation regulator/solenoid driver board. It's good practice to replace the 11,000uf/25V cap with a similar value. 12,000uf caps are a good choice. Here, a 15,000uf cap was used which also works fine.

The board also rectifies 49VAC to about 43VDC (probably a bit more) for use in solenoid circuits. General Illumination power (6.3VAC) also passes through the board, fused by two 15AFB fuses at FU6 and FU7.

5.2.1 Fuses and Test Points

The following table lists the circuit protection fuses for each circuit on the power supply.

FU1 - Solenoid Power - 5A (2 flippers), 6A (3 flippers), 7A (4 flippers)
FU2 - Display Power input - 3/4A
FU3 - 5V Logic Power - 6A
FU4, FU5 - 20VAC Controlled Lamp Power - 8A
FU6, FU7 - 6.3VAC General Illumination - 15A
FU8 - Display Power - 1/4A (a 3/4 inch fuse from the factory...suggest revising the power board to accept 1.25" fuses)

Other fuses are:
Bright Lights board F1 thru F16 - 3/4A (if there is no fuse bord in the back box, a game with Bright Lights has fuses under the playfield.
Bright Lights (under the playfield) C-phase and D-phase- 1A
Transformer fuse - 3A SB
Solenoids under the playfield fuse - 1A SB
Back Box Light Bulb fuse - 0.4A

The following test points are available on the power supply.

TP1 - 5VDC
TP2 - 190VDC, adjustable via the trim pot
TP3 - 230VDC, unregulated
TP4 - 43VDC
TP5 - 14VDC, unregulated
TP6 - 11VAC
TP7 - 11VAC
TP8 - 6.3VAC
TP9 - 6.3VAC
TP10 - Ground

5.3 MPU Issues

5.3.1 Relocating the Factory NiCad Battery off the MPU

The factory NiCad battery has been removed, a blocking diode has been added, and long leads provided so that the remote holder can lie comfortably in the bottom of the head.

Like other Bally and Stern MPUs that employ a battery on the MPU to provide power to the volatile RAM, it's a good idea to remotely locate the battery. The 6803 MPU provides an excellent place to locate a blocking diode so that the MPU charging circuit is blocked from attempting to charge the alkaline batteries. In the picture at left, two holes were drilled in the fat trace leading from the positive battery connection to the northwest. That trace was severed under the diode where the black line is shown, and the diode soldered across the severed trace with the banded end pointing away from the positive connection on the board. Be sure to provide enough wire to allow the remote holder to reach the bottom of the head making it impossible for leaky batteries to drip on the circuit boards.

Another option is to replace U4 (6116 ram) with a 6116 NVram module. Available at various sources these days. No soldering required.

5.3.2 Leon's 6803 CPU Repair

Leon's 6803 repair procedure has been added to the PinWiki, and can be found here.

5.3.3 Replacing header pins

Original headers shown on left...new header on the right. Note the damage to the plating on the old pins.

Bally 6803 header pins are different from every other game system header pins. Bally used pins without a "carrier". Over time, the plating on these pins fails, creating conductivity issues. These header pins can be replaced fairly easily. Simply heat each pin individually and remove them. It's best to heat the pin itself versus the pin/board junction as quite a bit of heat is required to remove the pins, which are "jammed" into the board. Installing a new strip of .100 pins may require a bit of tapping with a hammer as the new pins are larger in diameter.

Replaced .156 headers on a Bally 6803 MPU.

The same procedure may be used for .156 header pins on the MPU, as shown at left.

5.4 Solenoid Problems

5.4.1 General Solenoid Debugging Info

Bally 6803 game solenoids are driven from the row of TIP-102 transistors on the top edge of the master control board.

If one of these TIP-102s shorts, the coil/flasher will lock on, heat up, and eventually fail. When a TIP-102 is found to be shorted, examine the associated coil/flasher for shorts. Replace as necessary. Note that a coil resistance should never measure lower than 2 ohms.

The drive circuit for solenoids/flashers is...

• The 6803 processor programs the 6821 PIA at U7 output signals at PB0 - PB3 (called PB10- PB13 on the schematics which can be found here).
• The 6803 processor programs the 6821 PIA at U7 to pulse pin 19, CB2 (called CB12) enabling the chips select signal of U14
• Multiplexed (4 bits, PB10 - PB13) solenoid data presented at U14 (a 74LS154 4-to-16 decoder) is decoded when the chip select signal is enabled
• The decoder pulls the commanded signal (M0 - M14) to ground
• The ground passes through a 1.2K resistor on it's way to the base of a CA3081 integrated transistor array (U19 and U20), turning the transistor off
• With the CA3081 transistor turned off, power is then routed to the base of the TIP-102 (SE9302 Bally part number) turning it on and allowing coil power to conduct to ground and the coil to pull in or the flasher to turn on

A .002uf ceramic disk capacitor is incorporated across the collector and base of each TIP-102. On rare occasion, these capacitors can short causing the transistor to turn on and the coil/flasher to lock on. With the transistor removed, resistance between the center and top leg (ground) of each TIP-102 should be infinite (open). If resistance is anything other than infinite, there is a good chance that the ceramic capacitor is shorted.

TIP-102 transistors are easy to test.

• Set a DMM to diode check (the symbol looks like this -|<- )
• Black probe on transistor tab or center leg (they are connected internally)
• Red probe on each flanking leg one at a time
• A reading of .4 - .7 volts should be seen.
• Readings outside of these values indicate that the transistor has failed

Testing the CA3081 transistor arrays is simple also.

• Set a DMM to diode check (the symbol looks like this -|<- )
• Red probe on pin 15 of the IC
• Black on pins 1, 2, 4, 7, 9, 12 and 14 should read about .250
• Black on pins 3, 6, 8, 10, 11, 13 and 16 should read about 1.800
• Black on pin 5 will read shorted
• Readings outside of these values indicate that the transistor array has failed

5.4.2 Slingshots Inoperative

Be advised that some 6803 games (perhaps all) have a setting, in "Basic Settings", to turn slingshots on or off during game play. If the slingshot switches register by scoring in game play or during switch test, and the slingshot solenoids fire in test but not in gameplay, examine this setting. 0 = Off during game play, 1 = On during game play.

5.5 Lamp Problems

Like the prior game system, Bally 6803 games did not use a lamp matrix. All controlled lamps are turned on via SCRs (silicon controlled rectifiers, either 2N5060s or MCR-106s) on the MPU board. The SCRs on the MPU must be refreshed (turned on) at 60Hz since SCRs turn off when the AC sine wave passes through zero (called the zero cross).

The usual techniques for dealing with lamp problems should be employed.

Lamp always on

It's probable that the associated SCR is shorted on.

Lamp never on

Verify that the lamp is good by testing it in a working socket (like the backbox).
Verify that the lamp socket is good by jumping from a known good lamp socket to the suspect socket. If the lamp then lights, the socket and bulb are good.
Verify that the wire has not been severed by "buzzing" between the lamp socket and the associated lamp drive connector on the MPU.
Verify that the connector is working correctly by "buzzing" from the associated lamp drive SCR on the MPU to the lamp socket.
Test the SCR using the diode test.
Verify that the SCR is being turned on by the 4514.

Lamp sockets

An example of the worst lamp sockets ever used in a pinball machine.

In an effort to cut costs, the lamp socket style shown at left was used across quite a bit of the production run. While the "Spacer Invaders" era lamp sockets were bad, this style was even worse. If a tab breaks off, it's not cost effective to repair them. Simply replace them with a new socket of the more conventional 3 tab style.
‎

Internal connections of a 6803 vintage lamp socket.

Within the barrel of these sockets are the two connections to the lamp. In the picture shown at left, the lower conductor pair is spread too far apart and will not reliably light the lamp. The top conductor pair has been squeezed together using a small pick. The socket can be made reliable again by rehabbing the internal lamp conductors in this way.
‎

5.7 Display Problems

5.7.1 Flickering Displays

Displays that form the characters properly, yet flicker at something like a 50% duty cycle (on half the time, off half the time) are sometimes caused by low high voltage DC.

Nominal display voltage is 190VDC but this voltage can be "trimmed" down using the trim pot. Doing so has the advantage of extending the life of the plasma displays. Measure DC voltage at TP2 as you trim the voltage, to at least ensure that the voltage isn't being turned up. At some point (well below that level), the displays will begin to flicker.

Sometimes the root cause of the reduced voltage is a failed or open HV filter cap. The OEM HV filter cap which was originally a 160uf/350V cap, can be replaced by a commonly available 150uf/350V cap.

An odd but possible reason for flickering displays.

One very unusual reason for flickering displays is caused when the outhole switch "fish paper" becomes dislodged and allows the switch blade(s) to touch game ground. The behavior caused is different from the flicker caused by low high voltage discussed above. This flicker generally manifests on the left display and the segments lit do not form characters but seemingly random "noise". This anomaly occurs when the ball is in the outhole, and the playfield is positioned in its normal state (not propped up).

5.7.2 Display has all digits lit

bad left display

U1 socket a little higher than normal to allow soldering from the component side.

Displays that has all the characters lit, may have a bad 74HC373 at U1 on the display board. Replacing U1 will solve this problem. Do NOT use a 74LS373, this will not work. The LS version is "Low Power Schottky" and the HC version is "High Speed Cmos". Two different cookies. As the solder side of the board has the display glass at the position of U1, it may be difficult to replace U1. You can cut all the legs on the U1 and desolder every single leg one at a time. Put in a new socket and mount it a little higher than normal in such a way you can solder from the component side. That way you do not have to remove the (precious) display glass.

5.7.3 "Hot" Digits lit

Example of "Hot" digits...as if all digits are written to a single digit position

One might be tempted to indict the 4514 for this failure and that would be a reasonable assumption. However, more often, the issue is caused by a failed pair of digit drive transistors, MPS-A42 and 2N5401. Replacing this pair of transistors associated with the hot digit generally solves this issue.

A PinSide thread discussing this issue can be found here.

5.8 Sound Problems

5.8.1 Squawk & Talk Board

Since the Bally Squawk & Talk sound board is used for so many Bally -35 MPU games, the troubleshooting information regarding this board can be found in this -35 section.

5.8.1.1 Sound Test Reference

The following video links demonstrate properly operating Squawk & Talk sound boards.

Eight Ball Champ is demonstrated here.

5.8.2 TCS (Turbo Cheap Squeak) Board

Bally TCS Sound Board with modern reset generator installed at Q4. This board also has C30 removed per Bally service bulletin and one header connector replaced.

The schematics for the Turbo Cheap Squeak sound board can be found here.

This sound board has a common problem with DAC failure which is described in a Bally Service Bulletin. The failure can be prevented easily by removing the 47uf electrolytic capacitor at C30. Simply clip both of it's legs. Removing the capacitor seems to have no adverse affect while preventing a voltage condition on power down that can destroy the DAC. Since the AD7533 chip is getting harder to find and costlier to replace, making this change is strongly advised.

Like all other Bally sound boards of this vintage, replacement of the volume trim pot is advised. The TCS board uses a 1Kohm trim pot.

While the 6803 MPU lends itself to replacement of header pins, replacement of header pins on the TCS board is NOT advised. The .156 pins were wedged into the board very tightly and the solder pads, through holes, and traces on this board a extremely fragile. An attempt to remove/replace the header pins WILL cause additional damage (and repair work).

The reset circuit for this board is quite complex. Employing 4 TO-92 case transistors, resistors, zeners, and caps, a lot can go wrong. Fortunately, in the same way that MPU reset sections for Williams games can be replaced with a single component, we can modify the TCS (at least the -E000 version) board in the following way, as pictured at left. This modification removes the original reset components from the circuit (but not from the board) completely.

1. Remove D4, located to the right of the 5V regulator's heat sink.
2. Remove R12 and R15 located to the right of the 6821.
3. Remove Q1 and Q4.
4. Install a MCP120-460GI/TO reset generator (the same one that is used on Data East MPUs) into the Q4 position, oriented in the same way that Q4 was, but bring the middle leg to the top solder pad of where Q1 was. Be sure to avoid the old Q4 center leg solder pad.

No other modifications are necessary.

When you have sound, but it is crackling or slight buzzing, replace the 3 tantaal caps at C16, C25 and C28 with a new electrolithic 1uF/100V cap.

Flash numbers and meaning

• Flash 1 - The program ROM at U7 has passed checksum test.
• Flash 2 - The ram at U6 has tested good.
• Flash 3 - The 6821 PIA at U8 has tested good.

5.8.3 Sounds Deluxe Board

Bally Sounds Deluxe Sound Board

Location of C12 shown with cap removed.

The schematics for the Bally Sounds Deluxe Board can be found here.

This sound board also has a common problem with DAC failure which is described in a Bally Service Bulletin. The failure can be prevented easily by removing the 47uf electrolytic capacitor at C12. Simply clip both of it's legs. Removing the capacitor seems to have no adverse affect while preventing a voltage condition on power down that can destroy the DAC. Since the AD7533 chip is getting harder to find and costlier to replace, making this change is strongly advised.

The LED will flash at power on indicating test status. Completing 6 flashes means that the ROMS, RAM, and PIA have completed test successfully.

Flash numbers and meaning

• Flash 1 - The program ROM at U11 has passed checksum test.
• Flash 2 - The program ROM at U12 has passed checksum test.
• Flash 3 - The program ROM at U13 has passed checksum test.
• Flash 4 - The program ROM at U14 has passed checksum test.
• Flash 5 - Both 6116 (or 6264s if strapped for them) have tested good.
• Flash 6 - The 6821 PIA at U7 has tested good.

Bally Sounds Deluxe Sound Board J1 pinout

The pinout for the Bally Sounds Deluxe board is shown at left. The board can be booted on the bench with a 12VDC power supply. Connect 12VDC to pin 10. Connect all pins labeled ground together along with pin 15, which the manual labels "unregulated 14VDC return", which is another ground. Connect the power supply ground to any of the ground pins or to TP2 (GND).

If the 7805 voltage regulator on the board is working properly, measuring DC voltage between TP1 (5VDC) and TP2 should yield 5VDC.

The sound interface to the board is deceptively simple. Grounding pin 8 interrupts the big, powerful 68000 microprocessor on the board which reads the sound select inputs presented on pins 1 through 4 via the 6821 PIA at U7. Grounding pins 1 through 4, and then grounding pin 8 will generally produce sound. However, the interface isn't as simple as a 1 of 15 sound select, the maximum number of unique sound select bit patterns that 4 bits can define. Like the Squawk and Talk board, the interface uses a "command followed by command" design. Deciphering the actual interface might be quite a chore.

General troubleshooting

1. As with all of these old Bally sound boards, replacing the electrolytic caps is a good place to start.
2. Replace the 10K ohm volume pot
3. Test the socketed 6821 PIA at U7
4. Test the socketed RAM memory
5. Verify the ROM images are correct
6. Verify DC voltage between test TP1 (5VDC) and TP2 (GND) is 5VDC
7. Verify DC voltage at the positive lead of the 4700uf cap is about 14VDC
8. Pressing the red button should play a game tune, which may vary with each press of the button

When the soundboard does play sound, but one single sound plays when ever a sound must be heard, check the 6803 processor on the cpu board.
The sound commands come straight from the processor Peripheral lines.

5.10 Coins Register But Don't Credit Up

This is commonly seen on VPinMAME emulation, but applies to real life as well.

Coins drop OK, switch is good, game makes noise, but it remains on "Credits 0" and doesn't credit up.

Symptom is corrupted/blank NVRAM.

To fix, open coin door (make sure coin door switch is working, otherwise the keypad won't work), then do these steps:

Hit "Test", to enter operator mode.

Hit "A" until "Feature Options" is displayed.

Hit Enter.

It will say "Reset Factory Is".

Hit 6, then 5, then Enter.

Hit "Game" to return to attract mode. You'll know it worked because it will take longer than usual to reach attract mode, and the display will flicker slightly as the computer clears the memory (this is normal).

Intuitive and easy to remember, right? And Bally had the nerve to advertise "manual-free testing"....

6 Game Specific Problems and Fixes

Take note that J1 and J5 on the power supply board have the same pinouts, and can be plugged in incorrectly. Also, the input side of the transformer is the same as these two connectors. If the transformer input is plugged into J1, the trace from J1 pin 3 will burn up. Fortunately, it is not used in Motordome, and probably not used on other games either, as it is a single solenoid AC line destined for the playfield.

7 Repair Logs

Did you do a repair? Log it here as a possible solution for others.

7.1 Replace the 5V Regulator with EzSBC Switching Regulator

Replacing the 5V voltage regulator module with a new EzSBC switching 5V regulator is a viable option; there are many LM323 fakes, and 78H05C seems to be impossible to find.

The original 5V VRM was a 78H05C.

The EzSBC is easily obtainable and no longer needs the large and heavy heat-sink.

What needs to be done to replace the 78H05C with the EzSBC is to cut out R4 and replace R3 with a shunt wire.

A 22ga wire is sufficient.

Once replaced, the EzSBC should measure 5.1-5.2VDC at the test point TP1.

Close-up of modifications necessary for installing the EzSBC 5V regulator

7.2 MPU Can't Get Past 5th Flash

An MPU would not get past the 5th flash on a Strange Science, indicating a problem with the PIA located at u7. Leon's test ROM did not indicate any problems when testing on the bench and the PIA was good.

When bench tested with game ROMs, the MPU would complete the boot process successfully. So something in the game was responsible for the MPU being unable to complete its test sequence.

The issue ended up being a bad 74LS374 on the right display. After replacement the MPU booted fine in the game and worked properly.