Apple Lisa General Maintenance

Apple Lisa interior showing major components

Proper maintenance is essential to extending the lifespan and ensuring reliable operation of your Apple Lisa. As one of the earliest GUI-based personal computers, the Lisa requires special attention due to its age and the complexity of its systems.

Regular Cleaning

Internal Cleaning

• Power off and unplug the Lisa. Discharge the primary reservoir capacitors through a resistor and confirm with a meter that they have come down — waiting a set number of hours is not a discharge procedure, because a bleeder resistor that has failed open leaves the capacitor charged indefinitely
• Use compressed air to remove dust from the interior, paying special attention to the power supply and cooling vents
• Clean the motherboard (I/O board) and CPU board with a soft brush
• Inspect and clean the expansion card slots
• Check for signs of corrosion or electrolyte leakage from capacitors

External and CRT Cleaning

• Clean the exterior plastic with a damp cloth and mild soap
• Use appropriate CRT-safe glass cleaner on the display
• Clean air vents with compressed air to maintain proper airflow
• Inspect the rear connector panel for dust buildup

Keyboard and Mouse Cleaning

• The Lisa keyboard uses capacitive foam pads that deteriorate over time
• If keys are unresponsive, the foam and foil pads may need replacement
• Clean the keyboard housing with isopropyl alcohol
• The Lisa Mouse uses a steel ball that should be cleaned regularly

The battery pack — do this first

The single most destructive failure on a surviving Lisa is the battery pack, and it is not a single cell. The I/O board carries four NiCd AA cells in a holder on its lower right-hand side, with an on/off switch next to them — Apple's set-up procedure has the technician check that switch is set to ON before use.

Forty years on, almost every one of these packs has leaked. NiCd electrolyte is potassium hydroxide: strongly alkaline, and it wicks along traces and under components on the I/O board.

• Remove the cells before you do anything else to a machine that has been in storage — before recapping, before powering up, before testing.
• There is little point fitting replacements. Their only job is to hold up the floppy RAM and the real-time clock while the machine is unplugged; a Lisa left plugged in, even switched off, keeps both alive without them.
• Neutralise alkaline residue, clean with isopropyl alcohol, then check continuity on every trace in the affected area under magnification.
• See Battery Explosion, Capacitor or Corrosion Damage for the method and Apple Lisa Capacitor Replacement Guide for the trace-repair notes.

Whether a board has batteries at all identifies which machine you are holding: the Lisa 2 and 2/5 I/O board has them, the Macintosh XL (Lisa 2/10) board does not, and a board modified with the screen kit has them again.

Power Supply Maintenance

Critical safety capacitors

The Lisa power supply carries metallised-paper X-class (RIFA) capacitors across the mains input. Their epoxy shells crack with age, admit moisture and eventually fail with a bang and a cloud of acrid smoke.

• On the Lisa 2/10 supply (DataPower 699-0189) the two parts are C1 and C7, both 0.33 µF, 250 V. Values of 0.1 µF, 0.22 µF and 0.047 µF are sometimes quoted for these positions; they do not match the board. See Apple Lisa Capacitor Replacement Guide for the verified list.
• Replace both with modern X2-rated film capacitors of the same value, rated 275 V AC or better.
• Do this before the first power-on of a Lisa that has been in storage. The machine will usually still run after a RIFA lets go — these parts only filter interference — but the failure is alarming enough that people abandon working computers over it.

Electrolytic Capacitors

• Power supply electrolytics should be replaced if the unit has not been serviced
• Check for bulging, leaking, or corroded capacitor cans
• Use capacitors rated for the appropriate voltage and temperature

Common Failure Points

Power supply

• RIFA safety capacitors — the most common cause of smoke
• Electrolytic capacitors on both the primary and secondary sides; the primary reservoirs are 470 µF 250 V parts (C8 and C9) and hold a lethal charge after power-off
• Two supplies were fitted across the range: a 5 A supply rated at 1.2 A AC and a 10 A supply rated at 1.8 A AC. Which is present is one of the entries in Apple's configuration table for telling the Lisa variants apart
• Apple's own symptom/cure table is module-level throughout: a sizzling noise, a supply that trips on and off, an inability to adjust brightness or focus, all resolve to "replace power supply"

Memory boards

• The Lisa takes two identical memory boards (Apple part 661-93105). One board gives 512 KB; both give 1 MB, which is Apple's maximum. Third-party boards reach 2 MB
• The diagnostic diskette requires both boards to be fitted, as does every version of the Lisa Workshop — a machine that fails diagnostics with one board installed is not necessarily faulty
• If only one board is fitted, Apple specifies which slot it goes in; check the card cage labelling
• Oxidation on the edge connectors is common. Clean with isopropyl alcohol; a soft eraser works but leaves debris, so blow the slot out afterwards

I/O board

• Battery damage (above) is the dominant failure on this board
• Disk controller ROM: 341-0290 rev. B on the Lisa 2/5 board, 341-0281 rev. D on the Macintosh XL board
• At startup the machine prints the Boot ROM and I/O ROM codes in the upper right of the screen for a few seconds. The correct pairs are H / A8 for a Lisa 2 or 2/5 and H / 88 for a Macintosh XL (Lisa 2/10); with the screen modification kit fitted the boot ROM reads 3A instead of H. If what you read does not match, Apple's instruction is to fit the correct ROM
• The diagnostic diskette reports an I/O error on CPU boards whose boot ROM is earlier than rev. F
• Apple's error numbers 52 and 59 (I/O board COPS) and 54 (clock error) resolve to the I/O board alone; 55 and 56 are the two RS-232 ports

Floppy drives

• The Lisa 1's 5.25-inch FileWare ("Twiggy") drives hold 871 KB formatted each
• Sony 3.5-inch mechanisms in Lisa 2 models often seize as the lubricant dries. Clean and re-grease with a plastic-safe synthetic grease
• These mechanisms are direct drive — there is no belt to check or replace. See Macintosh Floppy Drive Maintenance

Widget hard drive (Lisa 2/10)

• The internal Widget drive is notorious for reliability issues
• No low-level format utility is publicly available
• Modern alternatives include X/ProFile and IDEfile emulators
• The external ProFile holds 4.98 MB formatted and connects to the built-in parallel port at the back of the machine — not to a serial port

CRT Maintenance

Discharge procedure

Apple's own service literature states that the Lisa picture tube "runs at over 15,000 volts DC" and contains a high vacuum. The anode holds that charge after the machine is unplugged.

• Always discharge the CRT anode before working near it — see CRT Discharge Procedure
• Apple's video adjustments are made with the power on, which is why its procedure carries its own safety section; read it before you start
• Do not use metal alignment tools anywhere near the video board

Display adjustments

Apple documents four groups of adjustment for the Lisa: the video board controls, horizontal phase, brightness and contrast, and the yoke and its adjustment magnets (Apple part 652-4520). Its summary table maps symptom to adjustment — bent or distorted lines, for example, go to the magnets on the yoke.

• Let the machine warm up for 10 to 15 minutes before adjusting anything
• Apple notes that video adjustments can slip in shipping, so a newly moved machine may only need adjusting rather than repairing
• An inability to adjust brightness or focus at all resolves, in Apple's table, to replace power supply — not to a video-board fault

Voltage checks

Apple publishes no per-rail voltages and no rail tolerances for the Lisa. The Lisa/Macintosh XL Technical Procedures contain video adjustments, diagnostics and module-level symptom/cure tables, and no rail measurement anywhere. The published electrical specification is the input side only: 90–130 V AC in the United States, 180–260 V AC in Europe and Asia, 48–68 Hz.

The table "+5 V 4.85–5.15 V, +12 V 11.9–12.7 V" circulates widely as though it were a general Macintosh specification. It is Apple's Macintosh Plus adjustment procedure, performed with voltage test cable 077-0135 on that machine's external floppy port, and with an upper bound of 12.75 V rather than 12.7 V. It does not apply to the Lisa, which predates it by three years and has no such test point.

What you can usefully check after power supply work:

• The +5 V rail against the specification of the 5 V logic it feeds, 5 V ±5 per cent — 4.75 V to 5.25 V.
• That no rail sags when a drive spins up.
• Ripple on an oscilloscope.
• Before touching the primary side, confirm with a meter that the 470 µF 250 V reservoir capacitors C8 and C9 have discharged. Those are what kill people working on switch-mode supplies, not the CRT.

Related Maintenance Pages

• Apple Lisa
• Apple Lisa Troubleshooting
• Apple Lisa Capacitor Replacement Guide
• CRT Discharge Procedure