Atari XE Game System Troubleshooting Guide
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Fault-finding on the Atari XE Game System (XEGS) starts with its own self test, described in Atari's owner's manual, and with knowing which start-up behaviours are normal.[1] The main board is assembly C100417. Its schematic exists as a redraw in JER/Eightbitter's 2016 reconstruction of a 130XE field service manual, which is not an Atari publication.[2]
Normal behaviour
[edit | edit source]- With no keyboard attached and no cartridge, the console starts Missile Command.[1]
- With the keyboard attached, it starts Atari BASIC. Holding SELECT at power-on starts Missile Command instead.[3]
- At every power-on the console tests itself for a few seconds before the first screen appears. If that check fails, the message "Memory Test" appears; Atari says this means the console needs servicing.[1]
Self test
[edit | edit source]Atari's procedure:[1]
- Switch off everything except the television or monitor.
- Hold OPTION and press POWER.
- The menu lists MEMORY, AUDIO-VISUAL, KEYBOARD and ALL TESTS. Press SELECT to choose a test (it blinks) and START to run it. A test runs until RESET is pressed; with the keyboard attached, HELP returns to the menu.
Typing BYE at the BASIC prompt also reaches the self test.[1]
| Test | Pass | Fail |
|---|---|---|
| Memory: two bars for ROM | Bars turn green | A red bar: ROM fault |
| Memory: 48 small squares for RAM, 1 KB each | Squares turn green | A red square: RAM fault |
| Audio-visual: a staff of six notes for each of the four voices | Each voice sounds and the colours stay consistent | A voice number appears with no sound, or the colours change during a voice test |
| Keyboard: an on-screen keyboard flashes the key pressed | Each key flashes and a note sounds | A key that does not respond |
Two results are not faults. Entered from BASIC with BYE, the memory test shows 40 squares instead of 48, because BASIC is using the other 8 KB; Ratcliff notes that the RAM under BASIC is then not tested.[1][3] Without the keyboard attached, only START, SELECT and OPTION can be tested.[1] Turn up the television's volume before the audio-visual test.[1]
Power
[edit | edit source]Atari specifies the supply as 1 A at 5 V DC, through the round power socket: pins 1, 4 and 6 are +5 V, pins 3, 5 and 7 ground and pin 2 the shield.[1] There is no regulator on the board for the logic supply; in the redrawn schematic the input runs from J7 through switch SW1 and choke L3 to the 1000 µF filter C13.[2]
- If the console is dead, measure the adaptor at its plug, then check the socket, its solder joints and SW1.
- With the adaptor unplugged and SW1 on, check for a short between +5 V and ground at the socket before fitting a replacement adaptor.
- The +5 V rail also goes out on pin 7 of both controller ports and pin 10 of the SIO port. Unplug every controller and peripheral when looking for a short or an overloaded supply.[1][4]
Devices and supply pins
[edit | edit source]The redrawn C100417 schematic gives some designators twice: U2 is used for a DRAM and for the 74LS138 decoder, and U7 for ANTIC and for the operating system ROM. Identify chips by their markings, and do not rely on U-numbers taken from it.[2] The supply pins below are properties of the chips themselves:
| Device | Package | +5 V | Ground |
|---|---|---|---|
| 6502C (SALLY) | 40-pin DIP | 8 | 1, 21 |
| ANTIC | 40-pin DIP | 21 | 1 |
| GTIA | 40-pin DIP | 27 | 3 |
| POKEY | 40-pin DIP | 17 | 1 |
| PIA | 40-pin DIP | 20 | 1 |
| FREDDIE | 40-pin DIP | 40 | 20 |
Source: chip pin assignment figures 1-5 to 1-10 of the 130XE manual reconstruction.[2]
The 64 KB of RAM is in two 64K × 4 DRAMs, so each chip holds four of the eight data bits.[3]
Chip-level checks from Atari's production test
[edit | edit source]Atari's XE/XL production test (revision 3.4, May 1986) predates the XEGS and does not name it, but its checks concern the same chips:[5]
- In its audio test the six tones come from POKEY and the following buzz from GTIA, so tones without the buzz point at GTIA.
- Missing or overlapping players, missiles or playfields, flecks of wrong colour at their edges, or gaps in the luminance and colour bands, indicate a bad GTIA. Atari notes that colours not lining up exactly horizontally is acceptable.
- Its RAM test prints the failing address, the data read and expected, and the failing bit numbers 1 to 8.
Symptoms
[edit | edit source]| Symptom | Check |
|---|---|
| Dead, power light off | Adaptor output at its plug; the power socket and its joints; SW1; a short on the +5 V rail |
| "Memory Test" on screen at power-on | The console's own check has failed. Run the self test and read the ROM bars and RAM squares |
| Starts BASIC instead of Missile Command | Normal with the keyboard attached |
| Starts Missile Command with the keyboard attached | Keyboard connector and cable, unless SELECT was held |
| No sound | Television volume, then the audio-visual test; POKEY produces the tones |
| Colour faults | GTIA, after checking the television's adjustment |
| Some keys dead | Keyboard contacts and the keyboard's two CD4051 multiplexers[3] |
| Cartridge not recognised | Clean the cartridge and slot contacts; switch off before inserting |
Things to avoid
[edit | edit source]- Inserting or removing a cartridge with the power on, and switching back on less than ten seconds after switching off. Atari's manual warns against both.[1]
- Exposing the XG-1 light gun's lens to intense light.[1]
- Using an XE computer capacitor list on this board. Its designators and several values differ; see Atari XE Game System Capacitor Replacement Guide.
Related pages
[edit | edit source]- Atari XE Game System
- Atari XE Game System General Maintenance
- Atari XE Game System Capacitor Replacement Guide
- Atari 130XE Troubleshooting Guide
- Atari 65XE Troubleshooting Guide
References
[edit | edit source]- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 Atari Corporation, Atari XE System Owner's Manual, C100608-001 Rev. A, 1987. Pp. 7 and 13–14, start-up with and without the keyboard; p. 15, system diagnostics and the "Memory Test" message; p. 16, memory test; p. 17, audio-visual and keyboard tests; p. 18, all tests; p. 19, care; p. 21, specifications; pp. 22–23, connector pinouts. Hosted as File:Atari XE Game System Owner's Manual C100608-001.pdf.
- ↑ 2.0 2.1 2.2 2.3 JER/Eightbitter, 130XE Personal Computer Field Service Manual, a 2016 reconstruction (PDF author "Jurek", created 15 November 2016), not an Atari publication. Figure 2-13, "XE-System Assembly C100417", schematic redrawn by jer/eightbitter (PDF p. 32); figures 1-5 to 1-10, chip pin assignments (pp. 11–13). Hosted as Atari 130XE Field Service Manual (PDF).
- ↑ 3.0 3.1 3.2 3.3 Matthew Ratcliff, "First Look Inside the XE Game System", Antic vol. 7 no. 4, August 1988, https://www.atarimagazines.com/v7n4/firstlook.php (retrieved 2026-10-01): keyboard and DB15 connector, two 64K × 4 DRAMs, start-up and self-test behaviour.
- ↑ Michael D. Current, Atari 8-Bit Computers: Frequently Asked Questions, last modified 29 November 2009, http://www.faqs.org/faqs/atari-8-bit/faq/ (retrieved 2026-10-01): SIO pinout (pin 10 +5 V/Ready); external power supplies C070042 (5 V 1 A) and C061982 (5 V 1.5 A).
- ↑ Atari Corporation, XE/XL Production Test Operator's Instructions, revision 3.4, 22 May 1986, in Atari 130XE Parts List and Production Test Instructions (PDF): audio test, video test reject criteria, RAM test failure display.