Atari 600XL General Maintenance
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General maintenance for the Atari 600XL: the power supply, keyboard, connectors, sockets and colour adjustment. Figures and part numbers are from Atari's 600XL Computer Field Service Manual.[1] Fault diagnosis and Atari's symptom checklist are on the Atari 600XL Troubleshooting Guide; capacitor values and positions are on the Atari 600XL Capacitor Replacement Guide.
Power supply
[edit | edit source]The 600XL takes +5 V DC through a 7-pin DIN socket, J4 (Atari part C061838). Pins 1, 4 and 6 carry +5 V, pins 3, 5 and 7 are the ground return and pin 2 is ground.[1]
| Parameter | Value |
|---|---|
| Atari part number | CA061982 |
| Input | 110 V AC nominal |
| Output | +5 V DC ±2 % (4.90–5.10 V) |
| Maximum rating | 1.5 A |
| Connector | 7-pin DIN |
Atari's parts list for the board has no rectifier or voltage regulator. The brick does the rectifying and regulating, and its output passes through the power switch SW1 straight to the three filtered +5 V rails, +5A, +5B and +5C.[1] Antic described the XL machines as the first Atari computers to need only a single 5 V DC supply.[2]
Checking the supply
[edit | edit source]- Measure the output at the plug with the brick disconnected from the computer. A reading outside 4.90–5.10 V is outside Atari's specification.[1]
- Inspect the DIN plug and socket for bent or corroded pins and a loose fit, and the cable at both strain reliefs.
- Inspect the solder joints at J4 on the board.
- On the board, Atari's procedure for a black or grey screen is to verify the +5A, +5B and +5C rails and the 3.58 MHz oscillator at Y1.[1]
A replacement supply must be regulated, wired to the 7-pin DIN with +5 V on pins 1, 4 and 6, rated for at least 1.5 A, and measured before it is connected.[1]
 | The 600XL has no regulator on the board. Whatever the supply delivers reaches the 6502C, ANTIC, GTIA and POKEY directly. Measure a supply before connecting it. |
Keyboard
[edit | edit source]The keyboard is a 3/4-stroke, 56-key unit: 55 alphanumeric keys including special characters and controls, and the space bar, with four function keys and a RESET key. It connects to the main board by a 24-conductor ribbon cable to the 24-pin header J8 (C061793), and the key matrix is read through two CD4051B multiplexers at U22 and U23 (C014336).[1]
To clean it, disconnect the power supply, blow debris from between the keys with compressed air and wipe the key tops with a cloth dampened with isopropyl alcohol. Note the orientation of the ribbon cable before unplugging it.
Atari's checklist points at U20 (POKEY), U22, U23, the keyboard and the cable when some keys fail, and at U20, U22 and U23 when every key fails.[1]
Connectors
[edit | edit source]| Designator | Connector | Atari part number |
|---|---|---|
| J1 | SIO, 13-pin right angle | C012995 |
| J3 | Cartridge, 30-pin | C014389 |
| J4 | Power, 7-pin DIN | C061838 |
| J5, J6 | Controller jacks, 9-pin right angle | C010448 |
| J8 | Keyboard header, 24-pin | C061793 |
- The SIO socket has ground on pins 4 and 6 and +5 V/ready on pin 10; pin 12 is not connected.[1]
- The controller jacks carry +5 V on pin 7 and ground on pin 8, so a shorted joystick cable loads the machine's supply.[1]
- Clean the cartridge slot contacts and the exposed Parallel Bus Interface fingers on the rear with isopropyl alcohol. Atari's schematic ties PBI pins 47 and 48 to +5A, although the pin-assignment figure lists them as reserved.[1]
The North American 600XL has no monitor socket; the PAL model has one, without separate luminance and chrominance signals.[2][3]
Memory and memory expansion
[edit | edit source]The 600XL has 16 KB of RAM in two 16K × 4 DRAMs at U11 and U12 (C061505), in 18-pin sockets. Atari's expansion is the 1064 48K Memory Expansion Module on the Parallel Bus Interface, which takes the machine to 64 KB.[1] Some late 600XLs, apparently only in Canada, left the factory with 64 KB fitted.[3] Internal 64 KB conversions are later modifications and are not in Atari's documents; on a converted machine, inspect the added wiring and sockets first.
If a 1064 is fitted, clean the PBI fingers on both the computer and the module, make sure the module seats fully, and check its own board for leaking capacitors and corrosion.
IC sockets
[edit | edit source]The CPU, custom chips, ROMs, RAM and logic are all socketed. Atari's parts list gives the sockets as 8-pin at U8; 14-pin at U7, U13, U14, U16 and U18; 16-pin at U1, U5, U6, U15, U19, U22 and U23; 18-pin at U11 and U12; 20-pin at U2; 28-pin at U3 and U4; and 40-pin at U9 (ANTIC), U10 (CPU), U17 (GTIA), U20 (POKEY) and U21 (PIA).[1]
Reseat socketed ICs if the machine is unreliable: power off, lift each chip with an extractor, clean the pins and press it back squarely, checking the orientation. Atari's checklist warns that the board must have a 74S32 at U18 and a Rev. E ANTIC at U9, or the RAM test fails.[1] Tech Tip 20 adds that the international ANTIC is C021698 and the domestic one C021697.[1]
Colour adjustment
[edit | edit source]R43 is the 500 kΩ colour trimpot (Atari part 19-411504). For no colour or bad colour, Atari's checklist lists U17, U19, Q6, Q1, CR1, CR2, Y1, the RF modulator or television tuner, R43 and U8, with the remedy "RF modulator adjust or color adjust".[1] Adjust R43 before replacing GTIA.
Related pages
[edit | edit source]- Atari 600XL
- Atari 600XL Troubleshooting Guide
- Atari 600XL Capacitor Replacement Guide
- Atari 600XL Field Service Manual
- Capacitor Failure Symptoms
- Recommended Tools
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 1.12 1.13 1.14 1.15 Atari, Inc., ATARI 600XL Computer Field Service Manual, FD100610 Rev. 1, October 1983: section 1 (power supply and figure 1-8, keyboard, SIO and controller pin assignments), section 3 (symptom checklist, pp. 3-1 and 3-2), section 5 (schematic and parts list, pp. 5-5 to 5-7) and section 6 (Tech Tip 20). Hosted on this wiki: Atari 600XL Field Service Manual (PDF).
- ↑ 2.0 2.1 Robert DeWitt, "Inside Atari: Evolution of the XL Computers", Antic Vol. 3 No. 2 (June 1984), atarimagazines.com. Source for the single 5 V supply and the 600XL driving only a television.
- ↑ 3.0 3.1 Michael D. Current (ed.), comp.sys.atari.8bit Frequently Asked Questions, last modified 29 November 2009, section 1.5, faqs.org. Community reference for the PAL monitor socket and the Canadian 64K machines.