Macintosh IIvi General Maintenance

This page covers routine care for the Macintosh IIvi. The IIvi, the IIvx and the Performa 600 share one enclosure, one power supply and one logic board design, and Apple documents all three in a single manual; the same case was later reused for the Centris 650.

Figures below come from Apple's Service Source for the IIvx, IIvi and Performa 600 and from Apple's Macintosh IIvx Developer Note, both hosted on this wiki.

What this machine is

Apple's specification for the Macintosh IIvi

Item	Figure
Processor	Motorola 68030 at 16 MHz with built-in MMU
Coprocessor	None. Apple lists the 68882 for the IIvx only
Cache	None. Apple lists the 32 K cache for the IIvx only
RAM	4, 5 or 8 MB, expandable to 68 MB
ROM	1 MB
PRAM	256 bytes
VRAM	512 K or 1 MB, upgradable to 1 MB
Expansion	Three NuBus slots and one accelerator slot
Serial	Two RS-232/RS-422 ports, 230.4 kbaud maximum (0.92 Mbit/s with an external clock)
A/C line input	100–120 VAC, 200 W
DC power	112 W maximum

Apple's figures. The IIvi is the slow member of the family: half the IIvx's clock, no FPU and no cache. Software that runs on a IIvx and crawls on a IIvi is not a fault.

Power supply

Apple service part 661-0758, the same unit as the Centris 650's. The logic board is 661-0760 for the IIvi (661-0759 for the IIvx, 661-0761 for the Performa 600).

Apple's developer note publishes the supply's ratings, which turn "is the supply all right?" into a measurement:

Apple's power supply ratings

Load	+5 V	+5 V TRKL	+12 V	−12 V	Total
Minimum	1.5 A	0 A	200 mA	0 A	9.9 W
Maximum	15 A	1 mA	2.5 A	600 mA	112 W
Peak	15 A	1 mA	6 A (12 s max)	600 mA	130 W

Those are Apple's figures. They are corroborated from the other direction: 68kMLA members reading the rating plates of physical units record Apple part 614-0009 (Astec AA16870 / Delta SMP-120EB), the same supply, as +5 V 15 A, +12 V 2.5 A, −12 V 0.6 A with a 1 mA continuous +5 V trickle. 15 × 5 plus 2.5 × 12 plus 0.6 × 12 is 112 W exactly.

Three things follow from that table:

• There is no −5 V rail on this machine. Apple's supply has four outputs — +5 V, +5 V trickle, +12 V and −12 V. Tables listing a −5 V rail for the IIvi are describing a machine that does not exist.
• The "230 W power supply" figure is wrong. Apple's Service Source gives the machine's A/C line input as 100–120 VAC at 200 W and its DC power as 112 W maximum, and the developer note's rating table agrees. 200 W is what the machine may draw from the wall including the monitor on the convenience receptacle; 112 W is what the supply delivers.
• The +12 V peak is deliberate. Apple designed it to carry 6 A for up to 12 seconds so that every internal drive can spin up at once. A machine that briefly sags on cold start and then settles is doing what it was designed to do.

The supply adapts automatically to anything from 85 to 270 VAC, contains the 80 mm fan that cools the whole system, and carries a switched convenience receptacle for the monitor rated at 3 A continuous.

What Apple does and does not publish

Apple publishes no rail tolerance and no power-supply adjustment procedure for the IIvi. The Service Source contains no acceptable-range table for any rail and no trimmer adjustment; every power fault in the symptom charts ends in "Replace power supply". The "+5 V 4.85–5.15 V / +12 V 11.9–12.7 V" table that circulates on pages of this era is Apple's Macintosh Plus procedure — genuine there, where it uses voltage test cable 077-0135 on the external floppy port — copied onto machines it was never written for. It has been removed from this page rather than reproduced, and no substitute has been invented.

What you can do instead is compare against a known load. Each rail at the logic-board power connector should sit close to its nominal value with the machine running and should not move when a drive spins up. A rail that is visibly low, or that sags under load, points at the supply. A rail that measures as a short to ground with the supply disconnected points at the logic board.

The +5 V trickle rail is the first useful go/no-go check on a dead machine. It is alive whenever the mains lead is in, switched on or not, because it powers the 68HC05 microcontroller's real-time clock, the parameter RAM and the ADB power-on circuitry. Present means the primary side is running and the fault is downstream; absent means the fault is in the mains input, the primary switcher or the standby circuit.

Recapping it

You are allowed to open this supply. Understand what is live in it first: it is mains-rectified, so with the cover off and the lead plugged in the fuse, input filter, bridge rectifier and reservoir capacitors sit at mains potential and hold a charge after the plug comes out. Unplug, discharge each large reservoir through a 1 kΩ / 5 W resistor, and confirm with a meter that it reads near zero before a tool goes near the primary side.

If your unit has two reservoir capacitors in series across the rectified mains, replace both together with matched parts. A single capacitor in place of the pair will fail on European mains, violently.

Battery

A 3.6 V lithium half-AA cell in a holder on the logic board keeps the real-time clock and parameter RAM alive with the machine unplugged.

Apple's check is a measurement, not a calendar. Set a meter to the 10 V DC range, put the positive probe on the positive end of the cell and the negative probe on the negative end, and replace the cell if it reads below 2.8 V. Apple publishes no replacement interval, and none is invented here: a cell above 2.8 V is doing its job and one below it should come out today whatever its age.

2.8 V is what Apple's manual for this machine says, and it is the figure most often got wrong: 3.0 V belongs to the Classic family, the LC series and the Quadra 605, and 3.2 V to the Centris and the larger Quadras. These thresholds are machine-specific and are routinely transplanted between pages. Use the one from your own machine's manual.

If it has leaked

This is a lithium cell, so neutralise with bicarbonate of soda, not vinegar. Vinegar is the right treatment for alkaline leakage, which is basic; it is the wrong treatment here and it adds water and chloride to an already corroded board. Use a paste of sodium bicarbonate and distilled water, rinse with distilled water, follow with isopropyl alcohol and dry thoroughly.

Then check the damage rather than assuming there is none:

• Inspect under magnification for traces that have gone dull, green or thin.
• Buzz out every track running away from the holder — corrosion travels under the solder mask and does not show from above.
• Check the underside of the board. Electrolyte wicks down through vias.

See Battery Explosion, Capacitor or Corrosion Damage and Battery Refurbishment.

Take the cell out before the machine goes into storage. That is not a service interval; it is the one measure that reliably prevents this damage.

The cell also powers the 68HC05 microcontroller that runs the real-time clock, parameter RAM and the ADB power-on circuit. That is why a flat battery on this chassis can present as a machine that will not respond to the power key at all rather than merely as a wrong clock.

Connectors and sockets

Oxidised contacts cause more intermittent faults on a machine this age than failed silicon does, and they are the cheapest thing to put right.

• SIMM sockets. Clean with isopropyl alcohol on a swab and reseat. Do not take an abrasive to a module's gold fingers — once you are through the plating, the base metal oxidises and then transfers to every socket the module touches.
• VRAM sockets. Same treatment. Video faults that come and go when the case is knocked usually start here.
• NuBus and PDS slots. Inspect for bent contacts and debris before a card goes home; check the card's edge fingers too.
• ROM SIMM socket, where one is fitted. A poorly seated ROM gives a machine that chimes and does nothing else.
• Logic-board power connector. Look for browning or a distorted housing. A discoloured power connector is a warning, not a cosmetic problem.
• ADB, serial, SCSI and floppy connectors. Reseat; check ribbon cables for cracked conductors where they fold.

A contact cleaner such as DeoxIT D5 earns its place on genuinely corroded contacts. It is not a preventive treatment and it does not belong on clean gold.

Capacitors

Eight electrolytics on the logic board: six 47 µF 16 V surface-mount and two 220 µF 16 V axial. MacDat and Recap-a-Mac's annotated photograph give the same complement, and Recap-a-Mac's board photograph is hosted here as File:Mac IIvi Recap Guide.jpg — the IIvi, IIvx and Performa 600 share one logic board design, so it applies to all three.

Designators and procedure: Macintosh IIvi Capacitor Replacement Guide.

Apple published no component-level capacitor data for any Macintosh of this era, so this is a community reading of physical boards. Read the value off each can before you lift it.

The failure pattern is the family one: audio first, then intermittent starting, then visible residue. A surface-mount electrolytic does not have to look swollen to have failed — the usual failure is a seeped seal and the evidence hides under the can. The two axial 220 µF parts are the ones people miss, because they do not look like the rest. See Capacitor Failure Symptoms.

Cleaning

Opening the case

1. Disconnect everything.
2. Remove the two Phillips screws at the rear top corners.
3. Slide the cover backwards and lift it off.

Inside

• Compressed air and an anti-static brush on the logic board, the supply and the fan. Hold the fan blade still while you blow it: spinning a fan with compressed air drives it as a generator and puts a reverse voltage back down its cable.
• Isopropyl alcohol (99 %) and a soft brush for grime, working outwards from each capacitor and from the battery holder.
• Check the underside of the board as well as the top. Both battery and capacitor electrolyte travel through vias.

Outside

• A damp microfibre cloth and mild detergent. No abrasives, no solvents — the texture on these shells does not survive either.
• ADB keyboards come apart for washing: keycaps off, warm soapy water, dry them completely, then clean the contacts with isopropyl alcohol.
• Mouse ball out, rollers scraped and wiped with isopropyl alcohol.

The platinum-grey plastics yellow with age. The discolouration is in the body of the plastic rather than on the surface, so cleaning will not shift it; see Retrobrite for what can be done and what it costs in brittleness.

Floppy drive

The 1.4 MB Apple SuperDrive is direct drive. It has no belt. Advice to fit a new belt to a sluggish or non-ejecting SuperDrive — including to the auto-inject version — is wrong: there is nothing there to replace. What these drives actually suffer is hardened grease on the head carriage and eject rails, dust in the mechanism, and dirty or worn heads. On manual-inject drives a worn eject gear is a genuine and common failure.

• Clean the heads with isopropyl alcohol on a lint-free swab, supporting the upper head arm so it is not sprung.
• If the rails are stiff, re-lubricate with a silicone grease — not white lithium grease, which gums up as it ages.
• If a disc will not eject, hold the mouse button down while switching the machine on to run a full eject cycle before taking anything apart.

See Macintosh Floppy Drive Maintenance.

Hard disk

The original SCSI mechanisms are past thirty years old and the usual failures are a stuck spindle, dried head-park grease and dead controller electronics. Solid-state replacements — BlueSCSI, ZuluSCSI, SCSI2SD — are quieter, cooler and considerably more reliable, and they let you keep the original drive on a shelf.

Whatever you fit, get the termination right: the drive at the end of the internal bus must be terminated, and the computer itself is always SCSI ID 7. See Macintosh HDD Maintenance.

Storage

• Take the battery out.
• Store dry and at room temperature — not a loft, not a garage.
• If the logic board comes out, bag it anti-statically and lay it flat.
• Nothing needs periodic running. "Power it up every few months to keep the capacitors formed" is repeated widely and supported nowhere for machines of this kind. The real hazard to a stored Macintosh is the cell in the battery holder, and removing it costs nothing.

Related pages

• Macintosh IIvi
• Macintosh IIvi Capacitor Replacement Guide
• Macintosh IIvi Troubleshooting
• Macintosh IIvx General Maintenance
• Macintosh IIvx IIvi and Performa 600 Developer Note
• Recommended Tools