Difference between revisions of "Atari Repair"
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Atari utilized a unique clocking system that utilized two independent clock channels - a main clock and an audio clock. To further complicate the issue, the main clock switches back and forth between two different speeds, depending on which portions of the boardset the CPU chip is accessing. When reading from the ROM chips, the main clock speed is generally seen as 1mhz. However, for most RAM and I/O circuits the main clock will slow to .67mhz due to the slower components being accessed. The audio clock runs at a fixed speed of 2mhz. (To be updated with clock testing procedures.) | Atari utilized a unique clocking system that utilized two independent clock channels - a main clock and an audio clock. To further complicate the issue, the main clock switches back and forth between two different speeds, depending on which portions of the boardset the CPU chip is accessing. When reading from the ROM chips, the main clock speed is generally seen as 1mhz. However, for most RAM and I/O circuits the main clock will slow to .67mhz due to the slower components being accessed. The audio clock runs at a fixed speed of 2mhz. (To be updated with clock testing procedures.) | ||
| − | Switch problems: many switches not recognized or operating one switch triggers several other | + | Switch problems: many switches not recognized or operating one switch triggers several other switches. Replace chips H7 (74LS244), E6 (7407), and D6 (7407). |
| − | Battery holder corrosion: There is a 3 AA battery holder made of aluminum that will corrode over time causing loss of battery backed data like replay scores and bookkeeping. Drill out the four rivets and unsolder the two terminals to remove the old battery holder. A new, | + | Battery holder corrosion: There is a 3 AA battery holder made of aluminum that will corrode over time causing loss of battery backed data like replay scores and bookkeeping. Drill out the four rivets and unsolder the two terminals to remove the old battery holder. A new, separate, 3 AA battery holder with wire leads can be mounted near the board. The wire leads will solder directly to the + and - terminals on the MPU board. You do not need to install an additional blocking diode, as there is already one in place on the circuit board. |
EPROM /PROMs: | EPROM /PROMs: | ||
Revision as of 21:23, 16 May 2012
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For history of Atari see Atari Pinball.
1 Introduction
Atari, widely known for their extensive video game library, also produced pinball machines for a short time during the late 1970's. In many ways, Atari went against the norm in both their design and style of their machines. All of the produced Atari machines, other than the massive Hercules, were widebody designs. Early machines featured score displays mounted in the apron area, with circuit boards in the lower cabinet.
After Hercules, in 1979, Atari ended their involvement in pinball, instead opting to focus on the video game and home console markets.
2 Games
- 4x4 (widebody, prototype)
- Airborne Avenger (widebody)
- Hercules (oversized, Gen2)
- Middle Earth (widebody)
- Monza (cocktail, prototype)
- Neutron Star (prototype)
- Pipeline (never produced)
- Road Runner (widebody, prototype, Gen3)
- Space Riders (widebody)
- Superman (widebody, Gen2)
- The Atarians (widebody)
- Time 2000 (widebody)
- Triangle (never produced)
3 Design Variations and Atari quirks
Atari pinball system can be effectively divided into two distinct generations, which will be referred to as Gen1 and Gen2. The vast majority of machines produced were manufactured utilizing the Gen1 board set. Only Superman and Hercules utilized the Gen2 system. Road Runner, of which only two machines were made, utilized a Gen3 design that was never put into production.
The two styles are easily distinguished both in their layout and locations. Gen1 boards incorporate all of their components into a single large sized circuit board, which is mounted in the lower cabinet below the playfield. Gen2 boards were split into two separate boards located in the headbox, a CPU board and an I/O board, which are connected via a 40 pin cable.
Note that while using the same basic board, Gen1 boards are not drop-in interchangeable. Boards were assembled according to the machines they were going to be installed into, and not all components were installed on the board. You will need to inspect a donor board to see which solenoid circuits are actually installed, and you may need to install additional circuits in order to activate all solenoids.
Atari took a very different approach to their circuit designs than other manufacturers of the same era. Rather than use an 8x8 matrix design for switches and lamps, Atari machines have discrete connectors and wiring for each lamp and switch. This results in a large number of wiring connectors and wires, as each switch and each lamp generally has its own dedicated wire and connection. Though in some cases, multiple switches may be daisy chained together, if they perform the same actions, such as Switch 20 on Superman machines.
Another interesting feature is that the insert lamps do not turn on and off like other manufacturers. Instead of being normally turned "off", lamps are kept turned on, but in a very dim state. When a lamp would be turned "on", it's switched from dim to bright. This was done intentionally, in order to extend bulb life, by reducing the stresses incurred in the filament when switching on and off. However this also means that Atari machines are not compatible with LED lighting for the inserts, as they would always be turned on.
4 Technical Info
Superman coils (all are 50 volts DC):
Atari # A007030-01 is used for the pop bumpers, slingshots, outhole, eject hole, and drop target reset. Approximate resistance is 6 ohms, and it has a 1N4001 diode soldered across the terminals. The coil has 1/4" quick connect terminals (no soldering needed). The coil sleeve is Atari # 006791-01.
Atari # A020470-01 (25/790) is the flipper coil. Has two diodes installed. The high current pull-in winding is 4.5 ohms dc resistance. The total resistance of the pull-in and hold windings is approximately 150 ohms. The coil has 1/4" quick connect terminals, so no soldering is needed. Uses Atari coil sleeve # 006791-01. Here is a close up picture of the diodes.
Marco Specialties stocks the Atari coils.
Flipper assembly on a Superman.
Pop bumper assembly on a Superman.
Eject hole kicker assembly on a Superman.
5 Problems and Fixes
5.1 Power Driver Issues
Pertains to Atari Superman and Hercules pinball (Atari Gen2 Circuit Boards)
If all playfield coils except for the flippers do not work, the likely suspect would be the chip enable circuit that is based around the CDN4013 chip located at B4/5, and also utilizes the MPS-A06 transistors at Q65, Q66, Q81, Q106 and the SJU783 transitor at Q103.
Other than the chip-enable circuitry, the solenoid driver section on the Gen2 Atari driver board is a very simple circuit layout. A single MC14514B line decoder controls each of the individual solenoid circuits. Each solenoid circuit consists of only an MPS-A06 pre-driver transistor, which drives the SJE783 driver transistor.
There is some confusion regarding driver transistors, as the schematic lists the driver transistor to be an SJE783, while the board layout lists a 2N6041, but most boards used an RCA8203B. The SJE783 is essentially impossible to find any information about, and the RCA8203B has been unavailable for quite some time. While the 2N6041 is available, a cheaper and more robust alternative would be the TIP107. Note that this applies only to Superman and Hercules boards, earlier machines used different components.
The MPS-A06 is still a commonly available part through most large electronics houses.
5.2 MPU Issues
Pertains to Atari "Superman" pinball.
Clocking: Atari utilized a unique clocking system that utilized two independent clock channels - a main clock and an audio clock. To further complicate the issue, the main clock switches back and forth between two different speeds, depending on which portions of the boardset the CPU chip is accessing. When reading from the ROM chips, the main clock speed is generally seen as 1mhz. However, for most RAM and I/O circuits the main clock will slow to .67mhz due to the slower components being accessed. The audio clock runs at a fixed speed of 2mhz. (To be updated with clock testing procedures.)
Switch problems: many switches not recognized or operating one switch triggers several other switches. Replace chips H7 (74LS244), E6 (7407), and D6 (7407).
Battery holder corrosion: There is a 3 AA battery holder made of aluminum that will corrode over time causing loss of battery backed data like replay scores and bookkeeping. Drill out the four rivets and unsolder the two terminals to remove the old battery holder. A new, separate, 3 AA battery holder with wire leads can be mounted near the board. The wire leads will solder directly to the + and - terminals on the MPU board. You do not need to install an additional blocking diode, as there is already one in place on the circuit board.
EPROM /PROMs:
Gen2: For Generation 2 circuit boards, there are two independent sets of ROM sockets designed into the circuit board. Locations K/L7, M7 and J7 are designed to use 2716 EPROM chips, while E5 thru K5 are intended for 1k PROM chips. The original thinking was that three of the (at the time) more expensive 2k EPROMS would be used during development and early production of a title. When the software was finalized, it would be written to six of the 1k PROM chips, as they were cheaper to produce if done in large numbers.
As the PROM chips are difficult to both acquire and write to, most users will simply use the EPROM sockets. Many boards do not even have sockets installed for the PROMs, making it a moot point.
5.3 Power Supply Issues
Pertains to Atari "Superman" pinball:
Fuses:
F1 Machine main power fuse, 5 amp slow blow, located on metal box on bottom of cabinet. F2 Service Outlet fuse, 2 amp slow blow, located on metal box on bottom of cabinet. F3 To BR1 & C1 (50 volts dc to coils), 15 amp slow blow, located in backbox. F4 To BR2 (+7 volts circuit), 15 amp slow blow, located in backbox. F5 To BR3 & C2 (+12 volts circuit), 7 amp slow blow, located in backbox. F6 For 6 volts AC general illumination circuit, 15 amp slow blow, located in backbox. Note: some machines may be incorrectly labeled as a 10 amp slow blow fuse. Fuseholder may tend to burn up. F7 Center tap of 6 volt circuit, 1 amp slow blow, located in backbox.
All three bridge rectifiers are type MDA3501.
5.4 Display Driver Board
Games produced previous to Superman, mounted the displays in the apron. Be careful as the displays are high voltage, and you can easily get a shock if you touch anything associated with the display wiring with the game on.
Games produced after Superman, including most prototypes, have the displays mounted in the head more like most other machines. They are still high voltage, but less chance of receiving a shock because of the mounting location.
6 Repair Logs
Did you do a repair? Log it here as a possible solution for others.