Macintosh IIvi General Maintenance

Macintosh IIvi logic board 820-0373-A with the electrolytic capacitors marked (Recap-a-Mac). The corroded area at right is the battery holder, BT1, beside the RAM SIMM sockets.

Routine care for the Macintosh IIvi, a 1992 desktop that shares its case, power supply and logic board design with the Macintosh IIvx and Performa 600. The parts that need attention are the lithium battery, the power supply and the logic board capacitors. The procedures are Apple's, from the Service Source for the three machines, unless another source is named.

Reference figures

Macintosh IIvi service figures

Item	Figure
Battery	Lithium; replace below 2.8 V on the 10 V DC range
Power supply	85-270 V AC, automatic; 112 W maximum, 130 W peak; monitor outlet 3 A
NuBus slots	13.9 W each, 41.7 W in total; Apple's chart says combined cards should not draw more than 45 W
Accelerator slot	5 W (1 A at +5 V)
Internal drives	3.5-inch: +5 V 1 A (1.1 A peak), +12 V 800 mA (3 A peak). 5.25-inch: +5 V 500 mA, +12 V 800 mA (1.5 A peak)
ADB port	+5 V on pin 3 through a 1 A fuse
RAM	Four identical 30-pin SIMMs, 80 ns or faster, all four sockets filled
VRAM	Two identical 68-pin VRAM SIMMs, 100 ns or faster: 256K each (512K) or 512K each (1 MB)
Part numbers	Logic board 661-0760; power supply 661-0758; floppy drive 661-0474 or 661-0121; internal chassis 922-0058; top cover 922-0056; speaker 922-0055

Opening the case

Loosen the captive screw at the rear, slide the top cover towards the front about an inch, and lift it off. When refitting it, do not knock the reset/interrupt switch and light pipe out of line.

Battery

When the machine is plugged in, the power supply's +5 V trickle output runs the clock and parameter RAM; the lithium battery takes over when it is unplugged. Apple's test: remove the cover, set the meter to the 10 V DC range, put the positive probe on the end of the battery marked "+" on the logic board and the negative probe on the other, and replace the battery below 2.8 V. To replace it, prise open the latch at the end of the holder with a small flat-blade screwdriver, lift off the cover and take the battery out.

Recap-a-Mac's photograph of a IIvi board shows the battery holder area badly corroded. Take the battery out before storing the machine. If it has leaked, neutralise the residue with bicarbonate of soda (vinegar is for alkaline cells), rinse, dry with isopropyl alcohol, and check the tracks around the holder on both sides of the board. See Battery Explosion, Capacitor or Corrosion Damage and Battery Refurbishment.

Power supply

The supply is Apple part 661-0758, the same unit as the Centris 650's. Apple Rescue of Denver lists it as Apple 614-0009, made by Delta (SMP-120EB) or Astec (AA16870). It adapts automatically to 85-270 V AC, carries the 80 mm fan that cools the whole machine, and has a switched outlet for the monitor rated at 3 A.

Power supply ratings (Apple developer note, Table 1-12)

Load	+5 V	+5 V trickle	+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 maximum)	600 mA	130 W

The supply has no -5 V output. The +5 V trickle output is present whenever the machine is plugged in, switched on or not, and powers the clock, parameter RAM and ADB power-on circuit. The +12 V peak rating allows all the internal drives to spin up at once. The Service Source prints the A/C line input as 100-120 V AC at 200 W and gives no rail tolerances or adjustment; its power faults all end at "replace power supply".

To remove it: take off the cover; if a CD-ROM drive is fitted, squeeze its side tabs and pull it forward an inch or two; remove the screw from the rear bezel; prise the latch away from the base of the supply; then lift the supply firmly out of the internal chassis, which disconnects it from the logic board.

The supply works from rectified mains and its reservoir capacitors hold a charge after it is unplugged. Discharge them and confirm with a meter before working on the primary side. The Macintosh Centris 650 Capacitor Replacement Guide has Console5's capacitor list for the Delta SMP-120EB version; there is none there for the Astec AA16870, so read the maker and model inside the supply before ordering parts.

Internal chassis, drives and logic board

1. Internal chassis: with the cover and power supply out, disconnect the floppy cable and the SCSI power and data cables (and the CD-ROM's power, data and audio cables if fitted), remove the two screws, swing the front of the chassis up until it is vertical and lift its tabs out of the slots in the bottom case. On refitting, seat its bottom corners in the guides.
2. Floppy drive: disconnect the cable, remove the mounting screw, prise up the mounting tab and slide the drive out. Apple fitted both auto-inject and manual-inject 1.4 MB drives; replace like for like.
3. Hard drive: disconnect the SCSI data and power cables, remove the screw from the carrier, lift the back of the drive and slide the carrier out.
4. Logic board: with the cover, power supply, internal chassis, reset/interrupt switch and speaker out, remove the screw in the centre of the board, slide the board forward about half an inch and lift it out. On refitting, put the centre of the rear edge into the plastic bracket and slide the board straight back, and move the SIMMs across.

Memory and video RAM

The four RAM SIMM sockets must all be filled with SIMMs of the same size and speed, 80 ns or faster. The two VRAM SIMMs are fitted in identical pairs, 100 ns or faster, and Apple warns that VRAM which does not meet its read-transfer timing can leave visible artefacts on the screen. A blank screen for a while at start-up is normal: RAM is tested and sized before video starts, and it takes longer with more RAM fitted.

SCSI and CD-ROM

An active terminator on the logic board terminates the internal bus when nothing is attached to the external SCSI port. The drive in the 3.5-inch position must be terminated, and a device in the 5.25-inch bay must not be. Apple's internal CD-ROM uses SCSI ID 3. The CD-ROM comes out after squeezing its side tabs and disconnecting the audio, SCSI power and data cables; the data cable connectors are keyed. See Macintosh HDD Maintenance.

Floppy drive

If a disk will not eject, switch off and hold the mouse button down while switching on. If that fails, push a straightened paper clip into the hole beside the drive slot. The drive is a direct-drive mechanism; see Macintosh Floppy Drive Maintenance.

Capacitors

The IIvi board Recap-a-Mac documents (820-0373-A) has six 47 µF 16 V surface-mount electrolytics and two 220 µF 16 V axials. Locations, parts and procedure are on the Macintosh IIvi Capacitor Replacement Guide.

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