Editing Macintosh IIvi Troubleshooting

This guide covers common faults with the '''Macintosh IIvi''', including startup failures, video problems, and storage errors.

== Preliminary Checks ==

Before detailed troubleshooting:

* Verify the power cable is secure
* Test with a known-good outlet
* Disconnect all external SCSI devices
* Remove any NuBus or PDS cards
* Check for visible capacitor leakage or battery corrosion

== No Power ==

<templatestyles src="Template:StyledTable/styles.css" />
[[File:Macintosh IIvi (photo).jpg|thumb|right|300px|Macintosh IIvi. Source: Wikimedia Commons.]]
{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+ '''Power Issues'''
|-
! Symptom !! Possible Cause !! Action
|-
| Completely dead || Blown fuse, failed PSU, bad cord || Check outlet; test power cord; check PSU fuse
|-
| Clicking or ticking || Failed PSU capacitors || Recap power supply
|-
| Powers on briefly then dies || Overload protection, shorted component || Disconnect cards and drives; test with minimal config
|-
| Fan spins but no startup || Dead PRAM battery, failed logic board || Replace PRAM battery; check for capacitor damage
|}

== Startup Failures ==

{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+ '''Startup Problems'''
|-
! Symptom !! Possible Cause !! Action
|-
| No chime, no video || Dead logic board, failed capacitors || Recap logic board; check PRAM battery
|-
| Chime but no video || VRAM issue, video connector || Reseat VRAM SIMMs; check video cable
|-
| Sad Mac error || Hardware failure || Decode error code; test RAM
|-
| Flashing question mark || No boot device || Check SCSI drive; verify termination
|-
| Chimes of death || RAM failure || Reseat or replace RAM SIMMs
|}

== Sad Mac Error Codes ==

{| class="wikitable styled-table" style="width:80%; text-align:center;"
|+ '''Common Sad Mac Codes'''
|-
! Code Range !! Meaning !! Action
|-
| 01XXXX || ROM test failure || Check for corrosion; may need logic board repair
|-
| 02XXXX – 05XXXX || RAM test failure || Try different SIMMs; clean SIMM slots
|-
| 0DXXXX || NuBus card failure || Remove all NuBus cards
|-
| 0EXXXX || SCSI controller failure || Check for capacitor damage
|-
| 0FXXXX || Data bus failure || Logic board damage
|}

See [[Sad Mac Error Codes]] for complete reference.

== Video Problems ==

{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+ '''Display Issues'''
|-
! Symptom !! Possible Cause !! Action
|-
| No video after chime || VRAM failure, cable issue || Reseat VRAM; check video cable and monitor
|-
| Distorted or garbled || VRAM configuration, bad VRAM || Ensure matching VRAM SIMMs; try removing VRAM upgrade
|-
| Wrong colors || VRAM issue, video DAC || Reseat VRAM; check for capacitor damage
|-
| Flickering || Loose cable, monitor issue || Check video cable; test with different monitor
|}

== Audio Problems ==

{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+ '''Sound Issues'''
|-
! Symptom !! Possible Cause !! Action
|-
| No startup chime || Audio circuit failure, capacitor damage || Recap logic board
|-
| Distorted audio || Failed capacitors || Recap logic board
|-
| No audio through jack || Jack issue, cable || Test with different cable/speakers
|}

== SCSI and Storage ==

{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+ '''Drive Problems'''
|-
! Symptom !! Possible Cause !! Action
|-
| Flashing question mark || No bootable System || Check SCSI drive; verify cable; test with boot floppy
|-
| Drive not recognized || Wrong SCSI ID, termination || Verify unique SCSI IDs; check termination
|-
| System freezes during boot || SCSI bus conflict || Disconnect all SCSI; add one at a time
|-
| Floppy not reading || Dirty heads, failed drive || Clean heads; test with different disks
|}

=== SCSI Termination ===
* Internal drive should be terminated
* If using external devices, terminate only the last device
* Verify each device has a unique SCSI ID (0–6)

== Capacitor-Related Failures ==

{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+ '''Capacitor Failure Symptoms'''
|-
! Symptom !! Likely Cause !! Solution
|-
| Random crashes || Failed logic board caps || Full logic board recap
|-
| Audio distortion || Caps near audio circuit || Recap logic board
|-
| No startup || Power or reset circuit caps || Recap; check traces
|-
| Intermittent operation || Multiple failing caps || Full recap
|}

See [[Macintosh IIvi Capacitor Replacement Guide]] for procedures.

== ⚠️ PRAM battery — remove it now ==

The Macintosh IIvi carries a 3.6&nbsp;V 1/2AA lithium PRAM battery. These leak and can '''burst''', spraying corrosive electrolyte across the logic board and destroying nearby components &mdash; often while the machine simply sits in storage. '''Remove the PRAM battery from any un-serviced unit.''' If one has leaked, neutralise and clean the residue and repair corroded traces and vias before troubleshooting.<ref name="mac2_batt">[https://68kmla.org/bb/threads/warning-exploding-maxell-pram-batteries.25169/ "Warning! Exploding Maxell PRAM Batteries"], 68kMLA; and [https://macdat.net/macintosh/macii/macintosh_iicx.html MacDat &mdash; Macintosh II family]. Source for the leaking/exploding lithium PRAM battery that destroys nearby components.</ref>

== ⚠️ Surface-mount capacitor leakage ==

The Macintosh IIvi logic board uses surface-mount electrolytic capacitors that leak with age and corrode the board; '''recap and clean the logic board''' as a first step, then recap the power supply.<ref name="mac2_cap">[https://macdat.net/macintosh/macii/macintosh_iicx.html MacDat &mdash; Macintosh IIcx/II family]; and 68kMLA recap threads. Source for the Mac II-family surface-mount electrolytic logic boards that leak and corrode with age and must be recapped.</ref>

== Power supply ==

The desktop power supply uses electrolytic capacitors that fail with age. The classic symptoms are a machine that will '''rarely turn on, cannot be switched off without unplugging it, and clicks from the PSU when merely plugged in'''. Recap the power supply and confirm the +5&nbsp;V and +12&nbsp;V rails. (This PSU form factor is shared across the IIci, IIcx, IIvi, IIvx, Performa 600, Quadra 650 and Quadra 700.)<ref name="mac2_psu">[https://68kmla.org/bb/threads/compact-desktop-power-supply-capacitor-lists-by-make-and-model.35890/ "Compact/Desktop Power Supply Capacitor Lists (by make and model)"], 68kMLA; and [https://www.bigmessowires.com/2016/04/21/capacitor-replacement-in-a-vintage-power-supply/ "Capacitor Replacement in a Vintage Power Supply"], Big Mess o' Wires. Source for the shared desktop PSU form factor (IIci/IIcx/IIvi/IIvx/Performa 600/Quadra 650/Quadra 700), the electrolytic failure symptoms and the PSU capacitor lists.</ref>

== References ==

<references />

== Component-level faults (deep dive) ==

=== Surface-mount capacitor leakage ===

The Macintosh IIvi logic board uses surface-mount electrolytic capacitors whose electrolyte turns corrosive with age and creeps across the board, eating through traces, pads and IC pins. Typical signatures are a machine that will not chime, chimes but shows no video, plays distorted or missing audio, or shows a garbled or checkerboard screen. Wash the affected area and replace every electrolytic with a tantalum or polymer part, then repair any lifted traces. The switch-mode power supply (ASTEC or TDK on the LC-family machines) holds its own electrolytics and fails the same way, so recap it alongside the board.<ref name="caps">Mac84, [https://mac84.net/web/macintosh-lc-series-lc-lc-ii-lc-iii-power-supply-recapping-guide-astec-usa/ Macintosh LC series power-supply recapping guide]; the [http://www.maccaps.com/MacCaps/Capacitor_Reference/Capacitor_Reference.html MacCaps capacitor reference]; and iFixit. Source for surface-mount electrolytic leakage eating traces, pads and pins, the ASTEC/TDK LC power-supply cap failures, and Apple's use of tantalum (non-leaking) capacitors on the Quadra 700/900 logic boards.</ref>

=== PRAM battery ===

The Macintosh IIvi backs up its clock and Parameter RAM from a 3.6&nbsp;V &frac12;AA lithium cell. These cells &mdash; red Maxell parts especially &mdash; leak or burst and corrode the board, so remove an aged one on sight. A flat cell can also stop a soft-power machine booting or disturb the video; left plugged in, trickle power preserves the settings, but a machine switched off at the wall with a dead cell loses them. Clean the area and fit a fresh 3.6&nbsp;V cell.<ref name="pram">[https://68kmla.org/bb/threads/warning-exploding-maxell-pram-batteries.25169/ Warning! Exploding Maxell PRAM batteries], 68kMLA; and [https://www.macdat.net/repair/kb/batteries_macintosh.html Mac Battery Leaks], MacDat. Source for the 3.6&nbsp;V &frac12;AA lithium PRAM cell, the Maxell leak/explosion board damage, and soft- versus hard-power PRAM retention.</ref>

=== Boot chime and Sad Mac ===

Read the start-up sound first: a normal chime with a black screen points to the display path or the monitor, an absent chime or a "chord of death" points to RAM or a core fault, and a Sad Mac shows a numeric code &mdash; see [[Sad Mac Error Codes]].

== Related Pages ==
* [[Macintosh IIvi]]
* [[Macintosh IIvi General Maintenance]]
* [[Macintosh IIvi Capacitor Replacement Guide]]
* [[Sad Mac Error Codes]]

[[Category:Apple Vintage Computers]]
[[Category:Apple Troubleshooting Guides]]