Atari 2600 General Maintenance

Atari 2600, opened

Routine care for the Atari 2600, from the six-switch CX2600 to the 2600 Jr. Fault diagnosis is on the Atari 2600 Troubleshooting Guide and capacitor values on the Atari 2600 Capacitor Replacement Guide. Designators, part numbers and voltages are from Atari's field service manual for the 2600 and 2600A.

Before you start

• Disconnect the power adaptor.
• Use an anti-static wrist strap. Atari warns that the four LSI chips (A200–A203 on the CX2600) are very sensitive to static and asks technicians to wear a grounding band and to remove chips with a chip puller.
• Work in a ventilated space when using solvents, and apply solvent with a brush or bud.

The largest capacitor is the 2200 µF 16 V reservoir: C106 on the CX2600 switchboard, C243 on a CX2600A. It sits on the unregulated input of roughly 9 V, so there is no dangerous stored charge in this console.

Cleaning

Case

1. Mild soap solution on a damp microfibre cloth.
2. Cotton buds around the switches and the cartridge slot.
3. Melamine foam for stubborn marks on textured plastic. It is a mild abrasive, so keep it away from printed graphics.
4. 70 % isopropyl alcohol for adhesive residue.

Inside

1. Blow loose dust out with compressed air.
2. Clean the board with a soft brush and 99 % isopropyl alcohol.
3. Look closely at the regulator and its heatsink, the cartridge connector, the controller ports and the power jack joints.
4. Let the board dry fully before reassembly.

RF shield

The shield tabs are twisted metal and fatigue if bent repeatedly; straighten them slowly with needle-nose pliers. On reassembly make sure the shield sits flat. On the CX2600, the manual's NTSC tech tips list several parts that must be kept clear of the casting when the motherboard goes back in: L200 and the "chicklet" capacitors under the shroud (tip 15), C220 and C239 pushed away from the J200 shroud (tip 17), and long leads trimmed on Taiwan-built units (tip 18). Motherboards of Rev 8 and earlier need an insulating dot over a trace in the upper-left corner so that it cannot touch the casting (tip 6).

Cartridge slot

The cartridge connector J200 is a 24-contact edge connector. Dirty contacts give a black screen, garbled graphics and games that only work when the cartridge is moved.

• With the console assembled, clean the contacts with a cotton bud or a lint-free cloth over a card, dampened with 99 % isopropyl alcohol, and let the slot dry.
• With the board out, check that the two plastic tabs in the slot are intact (they open the dust covers on Atari cartridges) and check continuity from each contact to its trace.

Early 2600s have a green J200 connector. Atari found it unreliable after many insertions and replaces it if a unit is intermittent when the cartridge is wiggled.

Switches

On the CX2600 the switches are on the switchboard: S101–S104 are slide switches, S105 and S106 are spring-return switches and S107 is an SPDT switch. On the CX2600A, S201 and S204 are DPDT slide switches, S202 and S203 are spring-return, and S200, S205 and S206 are PCB slide switches.

• Work a stiff switch through its travel repeatedly, then apply contact cleaner and work it again.
• Tip 14 in the manual's NTSC tech tips: reset any CX2600 switch that does not sit flat and square to the board.
• On the CX2600 the power switch is S101. Atari's flowchart replaces it when unregulated voltage reaches one side and not the regulator.

Atari's static modifications add static strips to the switches: C017294 and C017297 on the CX2600 switchboard, and strips on the front-panel switches of CX2600A boards of Revs 1–13.

Controller ports

The DE-9 ports oxidise, giving directions that do not register or an intermittent fire button. Spray contact cleaner into the port and insert and remove a plug several times. Tip 9: check J202 and J203 for pushed-back or broken pins and replace any that show problems. A broken port is replaced with a PCB-mount DE-9.

Power

Power input

The console takes unregulated DC from an external adaptor, which Atari calls the "battery eliminator". On the CX2600A the input is a 3.5 mm jack, J201 in the parts list; on the CX-2600A schematic the tip is positive and the sleeve grounded. A barrel plug does not fit it.

Tip 8 in the manual's NTSC tech tips: with a game running, move the power plug in a small circle; if the picture goes off, replace the jack. Reflow dull or cracked joints on the jack.

Voltage regulator

Regulation to +5 V is inside the console, by a 78M05 (Atari C014348, TO-220): A101 on the CX2600 switchboard, A203 on the CX2600A.

Expected voltages (Atari's CX2600 switchboard flowcharts)

Point	Expected
Regulator input (A101 pin 1)	7.5–9 V unregulated DC
Regulator output (A101 pin 3)	+5 V
J101 pin 1 (to the motherboard)	+5 V
J101 pin 2	+9 V

If +9 V is present at J101 pin 2 but +5 V is missing at pin 1, Atari's chart checks C101 for a short and otherwise replaces A101.

When refitting the regulator, clean the old compound off the tab and the heatsink, apply a thin film of fresh compound, and tighten the fixing firmly. Tip 19: on early units with a standup regulator and heatsink, look for hairline cracks between the regulator and the switchboard, and make sure the regulator is held firmly by its Tinnerman clip.

The 78M05 is a 500 mA part. A 7805 is the pin-compatible 1 A part. It does not run cooler: the dissipation is set by the input-to-output drop and the current the console draws.

Controllers

Atari CX40 joystick, opened

Joystick

Atari's section on game controllers describes the joystick as five calculator-type keypads on a small board, four under the stick and one under the button; a diagonal closes two at once. The earliest joysticks used five spring-loaded buttons, which Atari says cannot be repaired. Clean the board and the contact domes with isopropyl alcohol and check each direction with a meter or a game.

Paddles

Each paddle is a 1 MΩ potentiometer. Jitter comes from the track. Spray contact cleaner into the potentiometer and rotate it through its full range a number of times, or open it and clean the track. Replacement potentiometers need the right value and shaft.

Driving controller

The driving controller uses a switching device that produces a two-bit Gray code as it turns, not a potentiometer. Clean its contacts with contact cleaner.

Cartridges

• Clean the contacts with a cotton bud and 99 % isopropyl alcohol. A pencil eraser shifts stubborn oxidation; do not use anything harder on the gold plating.
• On Atari cartridges with a spring-loaded dust cover, hold the cover open while cleaning and release it gently.
• Clean labels with a barely damp cloth. Alcohol can lift the print.

Replacement parts

Common replacement components

Part	Specification
Voltage regulator	78M05 (Atari C014348), TO-220; a 7805 is pin-compatible
Power input jack (CX2600A)	3.5 mm jack, J201 (Atari 79-5918)
Main reservoir capacitor	2200 µF 16 V (C106 on the CX2600, C243 on the CX2600A)
Cartridge connector	J200, 12/24 contacts
Controller ports	DE-9, J202 and J203
Capacitors generally	See Atari 2600 Capacitor Replacement Guide

The TIA (A201) and the 6532 (A202) are Atari-numbered parts (C010444 and C010750); replacements come from donor consoles.

Related pages

• Atari 2600
• Atari 2600 Troubleshooting Guide
• Atari 2600 Capacitor Replacement Guide
• Atari 5200 General Maintenance
• Capacitor Failure Symptoms
• Recommended Tools