Atari Stacy General Maintenance
The Atari Stacy is a portable 1040ST-class machine, called the LST in Atari's engineering drawings.[1] It has its own DC-DC converter, a backlit LCD in the lid, a Trak-Ball and a battery compartment, so its maintenance differs from a desktop ST's.
Safety
[edit | edit source]- Disconnect the adaptor and remove any cells from the battery compartment before opening the case.
- The DC-DC converter board has a 1000 µF 25 V input capacitor, C101, across the 11–18 V input.[2] Discharge it before working on that board.
- While the machine is on, the same board produces an 85 V, 590 Hz output for the electroluminescent backlight.[2] Keep fingers off the backlight wiring and the converter's output side when testing a powered machine.
- The mains adaptor is a separate unit. Treat its inside as mains equipment.
Boards
[edit | edit source]| Assembly | Atari drawing | Contents |
|---|---|---|
| Main board | CA200464 Rev A (bill of material), schematic C103419 Rev 1 | 68HC000 CPU (U4), GLUE (U9), MMU (U19), Shifter (U20), DMA controller (U17), 68901 MFP (U10), two 6350 ACIAs (U6, U7), YM2149 sound (U8), 1772 floppy controller (U18), RP5C15 clock (U15), the LCD controller "Shadow" (U30) with its static RAM (U31), the ports and the lithium clock cell[1] |
| Sub board, 4 MB version | CA200528 Rev B (bill of material), schematic C103639 Rev B | 32 × 1M × 1 CMOS DRAM in ZIP packages (U5–U36), the HD6301V1 keyboard processor (U1), two TOS 1.4 EPROMs (U3, U4) in sockets, and a 1000 µF 16 V electrolytic (C7)[3] |
| LED board (in the lid) | CA200478 Rev B, schematic C103509 Rev A | LM386 audio amplifier (U1), LM337LZ regulator (U2), PC817 optocoupler (U3), the three lid knobs (VR1–VR3, one with a switch) and the indicator LEDs[4] |
| DC-DC converter | C101780 Rev B | Switching converter from the 11–18 V input to the logic, drive, LCD and backlight supplies[2] |
The package's sub-board bill of material is for the LST-4 (4 MB) board only.
Power supply
[edit | edit source]The converter's specified input is 11–18 V DC.[2] Atari's November 1989 product backgrounder gives the Stacy's power as twelve internal C cells or an external DC source through the DC input jack.[5] An adaptor reading anywhere inside 11–18 V is within the converter's input specification.
Atari's converter drawing labels each output with its nominal voltage and load range:[2]
| Output | Load range | Notes |
|---|---|---|
| +5 V | 0.5–2.2 A | Main logic supply; adjustable with a trimmer on the converter |
| +5 V | 0–0.3 A | On connector CN-B with +12 V |
| +12 V | 0–1 A | On connector CN-B |
| +5 V | 0–0.05 A | |
| +12 V | 0–0.05 A | |
| −12 V | 0–0.03 A | From a 79L12 regulator |
| −20 V | 0–0.03 A | |
| EL output | – | 85 V AC, 590 Hz, for the backlight; BRIGHT and EL OFF inputs from the lid knob |
The drawing gives no tolerances. Measure the main +5 V rail at the main board under load, during floppy and hard disk access, so that connector and cable drop is included, and use the converter's +5 V trimmer only after checking the input voltage and the converter's capacitors.
Clock battery
[edit | edit source]The main-board bill of material lists one C103655-001 "Battery lithium 3V 560mAh" at location LB.[1] It keeps the RP5C15 real-time clock (U15, with its 32.768 kHz crystal Y2) running while the machine is off.[1] It is a primary lithium cell, not a rechargeable pack. Replace it with a 3 V lithium cell of similar capacity, wired in with the same polarity. The machine runs without the cell but loses the date and time at each power-down.
If you find corrosion on a Stacy board, work out its source before treating it. Leaked alkaline C cells from the battery compartment are neutralised with a weak acid (vinegar); lithium cell residue is acidic and wants a bicarbonate solution. The procedure for both is on Battery Explosion, Capacitor or Corrosion Damage. Afterwards clean with isopropyl alcohol, inspect the traces under magnification and check continuity across the affected area before reassembly.
Battery compartment
[edit | edit source]The Stacy was designed to run from twelve C cells.[5] The lid carries a battery indicator light, and the converter has two warning outputs (WARN1, WARN2).[6][2] Remove the cells before storing the machine, so that a leaking alkaline cell cannot reach the boards. See Battery Refurbishment for battery handling generally.
Display
[edit | edit source]The display is a 640 × 400 monochrome supertwist LCD, driven as two halves split at line 200.[5] Its backlight is an electroluminescent panel fed with 85 V AC from the DC-DC converter.[2] The brightness, contrast and volume knobs are on the lid beside the screen. Turning the brightness knob fully anticlockwise switches the backlight off with a click.[6]
- A readable but unlit screen is often only the brightness knob at its off position, or the Mouse Accelerator III screen saver, which can switch off the backlight or the whole screen after a set idle time.[6] Check both before opening the machine.
- An external monitor on the monitor port shows the same image as the LCD.[6] Use one to separate a display fault from a logic fault.
- Clean the panel with a soft, dry microfibre cloth and do not press on it.
Trak-Ball and keyboard
[edit | edit source]- A slide switch on the right side panel selects the Trak-Ball (forward, "T-ball") or an external mouse on the Mouse/Joy port (back).[6] A Trak-Ball that does nothing may simply be switched to the external port.
- Clean the ball and its rollers with isopropyl alcohol on a lint-free swab.
- The keyboard is scanned by an HD6301V1 processor on the sub board (U1 on the 4 MB board), which talks to the CPU through one of the two ACIAs on the main board.[3][1] If no key responds, check the ribbon to the main board before suspecting either chip.
Drives
[edit | edit source]- Stacy 2 and Stacy 4 machines shipped with a 40 MB Conner hard disk.[7] Back it up before doing anything else.
- The internal drive is SCSI, connected through Atari's ACSI-to-SCSI host adapter on the Stacy's internal ACSI connector. That adapter supports one drive, at SCSI ID 0, unterminated, without parity, and addresses only the first 1 GB.[8] An SD-card SCSI emulator fitted in its place must be set up the same way.
- The Mouse Accelerator III "Automatic Parking" utility parks the hard disk heads after a set idle time.[6]
- For the floppy drive, clean the heads when a drive misreads. See Floppy Drive Repair and Hard Drive Maintenance and Repair.
Related pages
[edit | edit source]- Atari Stacy
- Atari Stacy Troubleshooting Guide
- Atari Stacy Capacitor Replacement Guide
- Atari Stacy Schematics and Drawing Package
- Battery Explosion, Capacitor or Corrosion Damage
- Capacitor Failure Symptoms
- Recommended Tools
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 Atari Corporation, STacy (LST) schematics and drawing package: bill of material CA200464-XXX Assy PCB LST Rev A, sheets 2–8 of 9 (PDF pp. 13–19). Sheet 2: electrolytic and ceramic capacitors; sheet 5: CPU, custom chips, crystals; sheet 6: RP5C15 clock U15, TL7705A U1, Shadow U30; sheet 7: connectors; sheet 8: sockets and the clock battery at location LB. Hosted as Atari Stacy Schematics and Drawing Package (PDF).
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Atari Corporation, STacy (LST) schematics and drawing package: DC-DC Converter, drawing C101780-XXX Rev B, sheet 6 of 7, drawn 28 February 1990 (PDF pp. 46–47, the left and right halves of the sheet). Shows "DC input 11–18V", C101 1000 µF/25 V, the output list (+5 V 0.5–2.2 A, +5 V 0–0.3 A and +12 V 0–1 A on CN-B, −12 V 0–0.03 A, −20 V 0–0.03 A, +5 V 0–0.05 A, +12 V 0–0.05 A, WARN1, WARN2) and "EL output 85V 590Hz" with the BRIGHT and EL OFF connections. Hosted as Atari Stacy Schematics and Drawing Package (PDF).
- ↑ 3.0 3.1 Atari Corporation, STacy (LST) schematics and drawing package: bill of material CA200528-XXX Assy Sub PCB LST-4 Rev B, sheets 2–5 of 6 (PDF pp. 6–9). Sheet 2: C7 1000 µF 16 V axial, 32 × 0.22 µF (C8–C39); sheet 3: DRAM C103641 1M × 1 ZIP at U5–U36, HD6301V1 at U1; sheet 4: TOS 1.4 EPROM pairs by country (U3 high, U4 low) and connectors J1–J3; sheet 5: 32-pin sockets at U3 and U4, 40-pin socket at U1. Hosted as Atari Stacy Schematics and Drawing Package (PDF).
- ↑ Atari Corporation, STacy (LST) schematics and drawing package: bill of material CA200478-XXX Assy LED PCB LST Rev B, sheets 2–4 of 5 (PDF pp. 10–12): capacitors C1–C6, VR1 10 kΩ, VR2 3 kΩ with switch, VR3 500 Ω, U1 LM386, U2 LM337LZ, U3 PC817, LEDs D1–D3, three knobs C103441-001 (listed as "volume knob"). Hosted as Atari Stacy Schematics and Drawing Package (PDF).
- ↑ 5.0 5.1 5.2 Atari Computer, Stacy Product Backgrounder, press release, Las Vegas, November 1989, pp. 1 and 8 (specifications: power "Internal by 12 standard 'C' batteries; DC input jack for use with external DC source"; display "Supertwist LCD monochrome with backlighting, split horizontally at line 200"; 32K static screen RAM; weight 15.2 lb including 12 C batteries). Scan at https://archive.org/details/19891100AtariComputersStacyAFullFunctionLaptop (retrieved 2026-10-01).
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 Atari Corporation, Stacy Addendum: Owner's Manual, C301421-001 Rev. A, 1989 (printed 1990). p. 7: brightness knob and backlight switch-off, Backlight/Screen screen saver; p. 8: Automatic Parking; p. 9: display, external monitor, Trak-Ball/mouse switch; p. 10: lid controls (brightness, contrast, volume, disk drive and battery indicator lights), lid release; p. 11: port covers, power adaptor. Hosted as File:Atari Stacy Owner's Manual Addendum C301421-001.pdf.
- ↑ Stephen Mortimer, "News, Notes & Quotes", START vol. 4 no. 9, April 1990: "The Stacy 2 and Stacy 4 have passed FCC Class A certification ... Both systems come with the respective amount of memory and a 40MB Conner hard disk drive." https://www.atarimagazines.com/startv4n9/newsnotesquotes.html
- ↑ Joska ([email protected]), Some notes about the Stacy/Mega STE internal SCSI host adapter, 2014 (community notes), p. 1. Copy at https://archive.org/details/manualzz-id-770197 (retrieved 2026-10-01).