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Atari 2600 Jr General Maintenance

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Atari 2600 Jr with top case removed
2600 Jr. with the top case removed and the RF shield in place

Routine care for the Atari 2600 Jr. The Jr. is a single board in a small two-part case, with an external power adaptor, a 7805 regulator, five slide switches and two push buttons.[1][2] Atari's 2600 field service manual does not cover the Jr., but it describes the same three LSI chips and the same controllers; the Atari 2600 General Maintenance page covers the joystick, paddles and driving controller.[3]

Atari's care notes

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The owner's leaflet asks owners to:[4]

  • switch the power off before inserting or removing a cartridge;
  • keep the console, controllers and cartridges away from extreme heat, and liquids away from the cartridge slot;
  • use only the AC power adaptor designed for the 2600, because another can damage the console;
  • clean the outside with a soft, slightly damp cloth.

Opening the case

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TBA's UAV manual describes the Jr.'s case as brittle and warns that its internal screw posts snap easily.[5]

  1. Unplug the adaptor and the RF cable.
  2. Remove the screws from the underside. R3UK's UK PAL Jr. had five.[6]
  3. Lift the left side of the top case first: SELECT and RESET are on a flexible cable that plugs into the board, and it must be unplugged before the top case comes away.[5][6]
  4. Release the snap levers at the left and right edges to lift the board out.[5]
  5. To remove the RF shield, straighten its tabs on the underside of the board.[5][6]

Refit the shield afterwards if the console will be used through its RF output; TBA says it is needed for a good RF picture.[5]

Power

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The PAL schematic shows the power path: input jack J2 with C2 (0.1 µF), the 2200 µF reservoir C26, the power switch S4, C37 (4.7 µF) and the 7805 regulator VR1. The power LED DS1 is fed through R57 (750 Ω).[2]

  • The regulator sits on a copper area of the board that serves as its heatsink; R3UK notes that this area is ground.[6] TBA has found Jr. consoles with nothing holding the regulator to the pad, and advises soldering the tab down or fitting a screw through the board.[5] The NTSC board in the photograph has a screw and nut.[1]
  • Console5's notes for the 2600 family say the original regulators run close to their current rating and often fail, and that the DC jacks work loose or get dirty, so that a tap on the plug can reset the console.[7]
  • Check the adaptor's output with a meter before connecting a console that has not been used for years.
Power checks
Test point Expected
Reservoir C26 Adaptor's DC output, with the adaptor plugged in
Regulator input (after S4) Same, with the power switch on
Regulator output +5 V

The positions are from the PAL schematic;[2] the 7805 regulates to +5 V by type.

Switches and buttons

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The board carries five slide switches, S1 to S5; S4 is the power switch, between the reservoir and the regulator.[1][2] The two push buttons, BT1 and BT2 on the PAL schematic, reach the board through connector J6 on the flexible cable.[2][6] The owner's leaflet names the power, TV TYPE and difficulty switches and the CHANNEL SELECTOR on the back, set to 2 or 3.[4]

Atari's advice for the earlier models' slide switches is on the Atari 2600 General Maintenance page.

Colour adjustment

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R9, a 500 kΩ trimmer next to the reservoir capacitor, sets the TIA's colour-adjust input (pin 10).[2][1] On the CX2600A Atari sets the equivalent control, R213, during the diagnostic cartridge's colour bar test, so that the bars above and below the thin reference line are within one shade of each other.[3] R3UK used the same trimmer to balance colour and sharpness after fitting a composite mod.[6]

Cartridge slot and chips

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The 2600 cartridge connector has 24 contacts in two rows of 12.[3] Clean them with the power off. The three LSI chips on the photographed NTSC board are soldered in, not socketed.[1]

Capacitors

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The Jr. has five electrolytics: C26 (2200 µF) and C20, C27, C29 and C37 (4.7 µF), plus the two 820 pF polystyrene capacitors C53 and C54 in the sound oscillator. Values, ratings and positions are on the Atari 2600 Jr Capacitor Replacement Guide.[7][2]

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References

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  1. ↑ 1.0 1.1 1.2 1.3 1.4 Evan-Amos, photograph of an NTSC Atari 2600 Jr. motherboard, Wikimedia Commons, public domain. Hosted here as File:Atari-2600-Jr-Motherboard-Flat.jpg.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Jerzy Sobola, redrawn schematic "Motherboard C012283 rev. B, Atari 2600 Game Console", sheet 1 of 2, 8 September 2000 (PAL 2600 Jr.). Hosted here as File:Atari 2600 Jr PAL motherboard schematic (Jerzy Sobola).png.
  3. ↑ 3.0 3.1 3.2 Atari, Inc., Video Computer System Field Service Manual, Domestic Model 2600/2600A, FD100133 Rev. 02: diagnostic cartridge colour bar test, cartridge connector J200 and section 7 (game controllers). It does not cover the 2600 Jr. Hosted here as Atari 2600 and 2600A Field Service Manual.
  4. ↑ 4.0 4.1 Atari Corp., Atari 2600 owner's leaflet for the 2600 Jr., C026260-001, 1986: installation and care notes. Hosted here as File:Atari 2600 Jr Owner's Manual C026260-001.pdf.
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 The Brewing Academy, Bryan's Ultimate Atari Video Rev. D Instruction Manual, revision 1.94, 23 March 2021, "Atari 2600 Jr." (p. 12). PDF from thebrewingacademy.com.
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 David Savery, "Atari 2600 composite video mods", R3UK, 2004, updated 2008 (a UK PAL "Revision A" Atari Jr.). Community project write-up.
  7. ↑ 7.0 7.1 Console5 TechWiki, "Atari 2600", "Other components related to refresh kits" (7805 regulator, DC jack) and the Junior capacitor lists. Community source; the capacitor lists are read from boards, not taken from Atari documentation.


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