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Atari STE General Maintenance

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Atari 1040STE

General maintenance for the Atari 520STE and Atari 1040STE. The two are built alike, with the keyboard, main board, power supply and a 1 MB floppy drive in one case, and differ only in the RAM fitted.[1] For the earlier ST, STF and STFM see Atari ST General Maintenance. Fault-finding is on the Atari STE Troubleshooting Guide and capacitors on the Atari STE Capacitor Replacement Guide.

How the STE differs from the ST

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  • The ST's GLUE and memory controller are combined in one 144-pin surface-mounted chip, the GSTMCU (C300589-001, U400).[2][3]
  • A new Shifter (C300588-001, U401) adds 8-bit stereo DMA sound. It is an 84-pin PLCC in a socket.[2][3]
  • RAM is on 30-pin SIMMs in four sockets, U600–U603.[2]
  • The BLiTTER (U101) is fitted as standard.[3]
  • TOS is in two 128K × 8 ROMs (U102, U103); the US machine in Atari's parts list has TOS 1.62.[2][3]
  • Two TL497A regulators on the main board make ±12 V for the RS-232 drivers and −5 V for the audio section.[4]
  • The left side has two extra game-controller ports (J500, J501) for joysticks, paddles and a light gun.[2][5]

Safety

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Warning: the internal switching supply runs from mains voltage. Unplug the machine before removing the supply shield, and discharge the supply's primary reservoir capacitor before touching the primary side. The supply has a 2 A fuse; Atari says a blown fuse probably means a catastrophic failure such as a shorted primary, so find the fault before fitting a new fuse.[4]

Opening the case

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Atari's sequence:[6]

  1. Turn the machine upside down. Remove the six screws in the square holes, which hold the top case. To reach the board or remove the drive, also remove the three screws in the round holes, which hold the drive.
  2. Turn it upright, lift off the top case and unplug the keyboard harness at the right front corner.
  3. Drive: lift it slightly and unplug the power harness and the ribbon cable.
  4. Power supply: remove one screw on the right of the supply shield and three screws between the rear EMI shield and the supply shield, straighten the two twist tabs and lift the shield off from the rear. Unplug the harness at the right front corner of the supply and remove the two screws at its front corners. For testing, the supply can stay in place with only the shield removed.
  5. Main assembly: remove three screws at the front of the shield and board assembly, lift it at the front and pull it forward.
  6. Upper shield: straighten the twist tabs (usually four), remove any copper tape and lift the shield straight up.

The power supply and the drive sit in the base with the main board; the top case carries only the keyboard.[6]

Power supply

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Atari's figures for the STE supply
+5 V +12 V
Rating 3 A 0.9 A
Typical in the system 1.75 A 86 mA
Maximum, during disk access 2.2 A 90 mA

Atari says to set the supply to 5.1 V. Maximum input power is 33.5 W.[4] Recapping the supply is covered on the Atari STE Capacitor Replacement Guide.

Memory

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Each bank is a pair of 8-bit SIMMs. Atari's rules:[2]

  • Every SIMM in the machine must be the same size; 256 Kbit and 1 Mbit SIMMs cannot be mixed.
  • All SIMMs should have the same access time, no slower than 150 ns.
  • 9-bit (parity) SIMMs can be used; the ninth bit is ignored.

The memory controller can address up to 4 MB.[2] Atari's US 1040STE has four 256 KB SIMMs, each with eight 256K × 1 DRAMs.[3]

To service the SIMMs, release the socket clips and remove each module, clean the edge contacts and the socket with isopropyl alcohol, and refit them firmly until the clips engage. For RAM faults, use the diagnostic cartridge's I and R codes on the Atari STE Troubleshooting Guide.

Socketed chips

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Atari's parts list gives sockets for the 68000 and the BLiTTER (68-pin PLCC, U100 and U101), the two TOS ROMs (32-pin, U102 and U103), the Shifter (84-pin PLCC, U401) and the SIMMs.[3] Reseat these if a machine is unreliable. Use a PLCC extractor on the PLCC sockets; levering one corner can crack the socket. The GSTMCU is soldered to the board.[3]

Reset at power-on

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STEs that do not start from cold but run normally once the reset button is pressed are common. exxos traced this to the reset circuit's capacitors, C100 and C102. His fix is to replace C102 with a new 22 µF capacitor and C100 with 47 µF; an alternative he and others used is a 22 µF capacitor soldered across C100. He suggests the same fix for STFM, Falcon and Mega machines with similar reset circuits.[7] Atari's parts list gives C100 as 10 µF 35 V and C102 as 22 µF 16 V.[3]

Cleaning

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Cleaning is the same as for the ST; see Atari ST General Maintenance#Cleaning. Also clean the SIMM contacts, and the two game-controller ports with isopropyl alcohol and compressed air.

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References

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  1. ↑ Atari Corporation, Atari STe 520/1040 Computer Field Service Manual, part number C302481-001 Rev A, August 1991, sections 1.0 to 1.2, pp. 1–2. The hosted copy is a retyped edition by jer/eightbitter (May 2017) with redrawn schematics: File:520ste.pdf, described at Atari 520STE/1040STE Field Service Manual.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Atari Corporation, Atari STe 520/1040 Computer Field Service Manual, C302481-001 Rev A, sections 2.0 to 2.12 (theory of operation; main memory in 2.6, game controllers in 2.12.8), pp. 4–21 (retyped 2017 edition, File:520ste.pdf).
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 Atari Corporation, Atari STe 520/1040 Computer Field Service Manual, C302481-001 Rev A, section 7, "Parts List", pp. 52–55 (retyped 2017 edition, File:520ste.pdf).
  4. ↑ 4.0 4.1 4.2 Atari Corporation, Atari STe 520/1040 Computer Field Service Manual, C302481-001 Rev A, sections 1.3, "Power Supply", and 1.4, "Negative Supplies", p. 3 (retyped 2017 edition, File:520ste.pdf).
  5. ↑ Atari Corporation, Atari STe 520/1040 Computer Field Service Manual, C302481-001 Rev A, section 3.17, printer and joystick port tests, and 3.21, error codes (retyped 2017 edition, File:520ste.pdf).
  6. ↑ 6.0 6.1 Atari Corporation, Atari STe 520/1040 Computer Field Service Manual, C302481-001 Rev A, section 4.1, "STE Disassembly", pp. 43–44 (retyped 2017 edition, File:520ste.pdf).
  7. ↑ exxos, "STE no reset on power up issue fix", exxos forum, 25 September 2019, with follow-up simulations of 17 June 2022, https://www.exxosforum.co.uk/forum/viewtopic.php?f=17&t=2175 (retrieved 2026-10-01).


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