Editing Macintosh IIx

{{Infobox computer
| name         = Macintosh IIx
| image        = [[File:Macintosh IIx.jpg|250px]]
| caption      = Macintosh IIx
| manufacturer = Apple Computer, Inc.
| type         = Desktop personal computer
| released     = 19 September 1988
| discontinued = 15 October 1990
| price        = US$7,800 / US$9,300 at introduction
| cpu          = Motorola 68030 at 15.6672 MHz (marketed as 16 MHz)
| fpu          = Motorola 68882
| memory       = 1 MB or 4 MB standard; Apple specifies expandable to 8 MB, 128 MB achievable with 16 MB SIMMs and 32-bit addressing
| rom          = 256 KB, "32-bit dirty"
| storage      = Optional internal 40 MB or 80 MB SCSI hard drive
| media        = Internal 1.4 MB SuperDrive; optional second internal drive
| graphics     = None built in — requires a NuBus video card
| sound        = Apple custom sound chip, 8-bit stereo sampling at 44.1 kHz, four-voice wavetable synthesis
| expansion    = Six NuBus slots, one processor-direct slot
| ports        = Two ADB, two RS-232/RS-422 mini DIN-8 serial, DB-25 SCSI, DB-19 floppy
| power        = 100–240 VAC auto-configuring, 48–62 Hz, 220 W maximum
| dimensions   = 5.5 × 18.7 × 14.4 in (14.0 × 47.4 × 36.5 cm)
| weight       = 24 lb (10.9 kg)
| os           = System 6.0.2 onwards
| predecessor  = [[Macintosh II]]
| successor    = [[Macintosh IIfx]]
| codename     = Spock, Stratos
| model        = M5840 (order no. M5280); Gestalt ID 7
}}
The '''Macintosh IIx''' was introduced on 19 September 1988 as an incremental revision of the [[Macintosh II]]. It kept the six-slot NuBus chassis and swapped the 68020 for a 68030 at the same clock, added a 68882 as standard and fitted the 1.4&nbsp;MB SuperDrive — the first Macintosh II to ship with one.<ref name="everymac" />

Everything on this page that is a number comes from Apple's own ''Service Source'' for the Macintosh II, IIx and IIfx, hosted on this wiki, or from a named community source that says where it got it.<ref name="ss-ii">Apple Computer, ''Service Source: Macintosh II/IIx/IIfx''. Hosted on this wiki as [[:File:Macintosh ii.iix.iifx.pdf]]; see [[Macintosh II/IIx/IIfx Service Source]]. Chapters used: Specifications (Processor, Memory, Disk Storage, I/O Interfaces, Sound and Video, Electrical, Physical), Troubleshooting (Symptom Charts), Take Apart, Additional Procedures (Battery Verification, Battery Replacement, Battery Holder Board, Macintosh IIfx SCSI Termination) and Exploded View.</ref>

== Specification ==

<templatestyles src="Template:StyledTable/styles.css" />
{| class="wikitable styled-table" style="width:88%;"
|+ Apple's specification
! Item !! Figure
|-
| Processor || Motorola 68030 with built-in paged memory management unit
|-
| Coprocessor || Motorola 68882
|-
| Addressing || 32-bit registers, 32-bit address bus, 32-bit data bus
|-
| RAM || 1 MB, expandable to 8 MB (Apple's figure — see below)
|-
| ROM || 256 K
|-
| Floppy || Internal 1.4 MB drive; optional second internal 1.4 MB drive
|-
| Hard drive || Optional internal 40, 80 or 160 MB
|-
| SCSI || 5 MB/s transfer rate, eight devices maximum
|-
| ADB || Two ports, daisy-chainable
|-
| Serial || Two RS-232/RS-422, mini DIN-8
|-
| NuBus || Six internal slots, full 32-bit address and data buses
|-
| Sound || Apple custom digital sound chip: 8-bit stereo sampling at 44.1 kHz, four-voice wavetable synthesis, drives stereo headphones through the sound jack
|-
| Line voltage || 100–240 VAC, automatically configured
|-
| Frequency || 48–62 Hz, single phase
|-
| Maximum power || '''220 W''', monitor excluded
|-
| Dimensions || 5.5 × 18.7 × 14.4 in (14.0 × 47.4 × 36.5 cm)
|-
| Weight || 24 lb (10.9 kg), more with an internal hard drive
|}

All of that is Apple's.<ref name="ss-ii" /> Three corrections to figures that circulate widely:

* '''220 W, not 230 W.''' Apple gives 220&nbsp;W for the II and IIx and 230&nbsp;W for the IIfx. The two get swapped.<ref name="ss-ii" />
* '''The supply is auto-configuring, not switch-selectable.''' Apple specifies 100–240&nbsp;VAC "automatically configured". There is no voltage selector switch to set wrongly.<ref name="ss-ii" />
* '''The model number is M5840''', order number M5280 for the 1&nbsp;MB configuration; Gestalt ID 7.<ref name="everymac" />

=== Memory ===

Apple's published ceiling is '''8 MB''' — eight 30-pin SIMM sockets in two banks of four, filled in groups of four, 120&nbsp;ns or faster.<ref name="ss-ii" /> In practice the machine addresses much more: with 16&nbsp;MB SIMMs in all eight sockets, 32-bit addressing and the MODE32 extension, a IIx will run '''128 MB'''.<ref name="everymac" />

The reason Apple's number is lower is the ROM. The IIx's 256&nbsp;K ROM is '''"32-bit dirty"''' — it contains 24-bit addressing code — which caps usable memory at 8&nbsp;MB unless MODE32 or the 32-Bit System Enabler patches it.<ref name="everymac" /> This is a software limit with a software fix, not a hardware fault, and a IIx that reports 8&nbsp;MB with more fitted is behaving exactly as documented.

Apple also names a specific memory fault on this family: '''Apple-labelled SIMMs manufactured by NEC with a date code of 9052 or below''' are the first thing its symptom charts tell a technician to replace for an error chord at startup, for a system that will not boot, for video ghosting and for a system that boots and then loses video.<ref name="ss-ii" /> Four separate symptoms, one part. If you have unknown-provenance Apple SIMMs in a machine doing any of those things, read the date codes.

=== A note on the clock figure ===

Apple prints two different numbers for the same design. The ''Macintosh II/IIx/IIfx Service Source'' gives the II and IIx as '''15.6772 MHz'''; the ''Macintosh IIcx/IIci/Quadra 700 Service Source'' gives the IIcx — the same 16&nbsp;MHz-class design — as '''15.6672 MHz'''.<ref name="ss-ii" /><ref name="ss-iicx">Apple Computer, ''Service Source: Macintosh IIcx/IIci/Quadra 700''. Hosted on this wiki as [[:File:Quadra 700.mac iicx.iici.pdf]]; see [[Macintosh IIcx/IIci/ Quadra 700 Service Source]]. Chapters used: Specifications, Troubleshooting (Symptom Charts), Take Apart and Additional Procedures (Battery Verification).</ref> The second is the one to believe: the boards carry a '''31.3344&nbsp;MHz''' crystal, which is exactly twice 15.6672&nbsp;MHz, and it is legible in Recap-a-Mac's photograph of the IIcx board.<ref name="ramcx">Recap-a-Mac, Macintosh IIcx — https://recapamac.com.au/macintosh-iicx/ . Annotated photograph of the 820F0230-B logic board. Hosted on this wiki as [[:File:Mac IIcx Recap Guide.jpg]]. Secondary source. Also legible in the photograph: the board’s 31.3344 MHz crystal at Y2.</ref> "16 MHz" is the marketing figure and what EveryMac and Apple's own sales material use.<ref name="everymac" />

== Power ==

Power supply Apple part '''661-0375''', shared with the Macintosh II; the IIfx uses 661-0542. Logic board 661-0529 (661-0528 for the II, 661-0522 for the IIfx). Bottom cover 630-5494 distinguishes a IIx from a II (630-5227) and a IIfx (630-5806).<ref name="ss-ii" />

=== What Apple does and does not publish ===

'''Apple publishes no rail tolerance and no power-supply adjustment procedure for the Macintosh II, IIx or IIfx.''' 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".<ref name="ss-ii" /> The "+5&nbsp;V 4.85–5.15&nbsp;V / +12&nbsp;V 11.9–12.7&nbsp;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. Neither it nor any invented substitute appears on this page.

Apple does give one rail check, in the hard-disk symptom chart: if an internal drive will not spin and its LED does not light, '''verify the +5&nbsp;V and +12&nbsp;V lines to the drive''' before replacing anything.<ref name="ss-ii" /> That is a presence test, not a tolerance test, and it is the only rail measurement Apple asks for.

=== Recapping the supply ===

You may open it, and on a machine this age you probably should. 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&nbsp;kΩ / 5&nbsp;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 ==

'''This machine has two lithium cells, not one.''' Apple's battery verification and replacement procedures for the II, IIx and IIfx are written in the plural throughout, and the illustration shows a pair of holders side by side; the symptom charts say "check batteries".<ref name="ss-ii" /> Recap-a-Mac's board photograph shows both holders.<ref name="ramx">Recap-a-Mac, Macintosh IIx — https://recapamac.com.au/macintosh-iix/ . Annotated photograph of the 820-0229-A logic board, with each electrolytic marked with its value, working voltage and positive terminal, and a value-and-count summary. Hosted on this wiki as [[:File:Mac IIx Recap Guide.jpg]]. Secondary source: one repairer’s reading of boards handled personally.</ref>

* Set a meter to the '''10 V DC''' range.
* Positive probe on the end of the cell marked "+" '''on the logic board''', negative probe on the other end.
* '''Replace the battery if it reads below 3.2 V.'''<ref name="ss-ii" />

'''3.2 V is this machine's figure.''' It is not the 2.8&nbsp;V of the [[Macintosh IIcx|IIcx]], [[Macintosh IIci|IIci]] and [[Macintosh Quadra 700|Quadra&nbsp;700]], nor the 3.0&nbsp;V of the [[Macintosh IIsi|IIsi]] and the LC series. Apple's thresholds are machine-specific and get transplanted between pages; use the one printed in your own machine's manual.

Apple's removal is simple: prise the latch away from the holder with a small flat-blade screwdriver, lift the cover off and lift the cell out.<ref name="ss-ii" />

=== Machines with no battery holder ===

'''Early Macintosh II and IIx boards have their cells soldered directly to the logic board.''' Apple's own instruction is unambiguous: before you change the batteries in a Macintosh II or IIx that has no battery holder, '''fit the battery holder board first'''.<ref name="ss-ii" />

Apple's cautions on that job are worth repeating because both are easy to get wrong:

* '''Do not force the old connections free''' — you will pull the copper off the board.<ref name="ss-ii" /> Remove the wire from each hole and clear the hole of solder instead.
* '''The holder board is polarised.''' Apple marks the positive holes on the logic board, and putting the holder in the wrong way round may damage the board.<ref name="ss-ii" />

If your machine still has soldered cells, this is the single most valuable preventive job you can do to it. A soldered cell cannot be removed for storage, and a soldered cell that leaks takes the traces underneath it with it.

=== If it has leaked ===

'''These are lithium cells, so neutralise with bicarbonate of soda, not vinegar.''' Vinegar is the right treatment for alkaline leakage; it is the wrong treatment here and it adds water and chloride to an already corroded board. Bicarbonate paste in distilled water, rinse with distilled water, follow with isopropyl alcohol, dry thoroughly — then buzz out every track running away from the holders, and check the underside of the board. See [[Battery Explosion, Capacitor or Corrosion Damage]] and [[Battery Refurbishment]].

'''Take the cells out before the machine goes into storage.'''

== Capacitors ==

Logic board '''820-0229-A'''. Twenty electrolytics:<ref name="macdat">MacDat Capacitor Reference Library, Apple section — https://macdat.net/repair/cap_reference/apple/ . Secondary source: a community-maintained capacitor reference compiled from physical boards, giving value-and-count lists and, for most boards, an annotated reference photograph. Used here for the per-board electrolytic complements quoted, which agree with Recap-a-Mac’s independently produced board photographs wherever both cover the same board.</ref><ref name="ramx">Recap-a-Mac, Macintosh IIx — https://recapamac.com.au/macintosh-iix/ . Annotated photograph of the 820-0229-A logic board, with each electrolytic marked with its value, working voltage and positive terminal, and a value-and-count summary. Hosted on this wiki as [[:File:Mac IIx Recap Guide.jpg]]. Secondary source: one repairer’s reading of boards handled personally.</ref>

{| class="wikitable styled-table" style="width:75%; text-align:center;"
|+ Macintosh IIx logic board 820-0229-A
! Value !! Working voltage !! Quantity !! Package
|-
| 47 µF || 16 V || '''15''' || Surface-mount
|-
| 470 µF || 16 V || '''3''' || Axial
|-
| 220 µF || 16 V || '''1''' || Axial
|-
| 10 µF || 16 V || '''1''' || Axial, with surface-mount pads also present
|}

'''Two independent community sources give exactly that complement''' — MacDat's reference list and Recap-a-Mac's annotated photograph of an 820-0229-A board, which is hosted here as [[:File:Mac IIx Recap Guide.jpg]].<ref name="macdat" /><ref name="ramx" /> Console5's per-designator list for the same board agrees value for value.<ref name="console5">Console5 TechWiki, Apple computer pages — https://wiki.console5.com/wiki/Category:Computer . Secondary source: community-maintained per-designator capacitor lists compiled from physical boards. Used here for logic-board assembly numbers and per-designator capacitor lists where Console5 carries the board.</ref>

[[File:Mac IIx Recap Guide.jpg|center|thumb|750px|Macintosh IIx logic board 820-0229-A with every electrolytic marked with its value, working voltage and positive terminal. The two battery holders are visible above centre. Source: Recap-a-Mac.]]

Apple published no component-level capacitor data for any Macintosh of this era, so all three sources are readings of physical boards rather than manufacturer specifications. They agree, which is about as good as corroboration gets. Read the value off each can before you lift it.

'''The four axial parts are the ones people miss.''' They do not look like the surface-mount cans and they sit apart from them, but they are electrolytic and they age the same way. The 10&nbsp;µF position has surface-mount pads underneath it, so it can be rebuilt either way.

What failure looks like: audio faults first, then intermittent starting, then visible residue — brown or amber staining around a base, dull solder mask nearby, green or white crystalline deposits where electrolyte has reached copper. A small 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. See [[Capacitor Failure Symptoms]].

== 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.

== Cleaning ==

=== Opening the case ===

Release the catches at the rear and slide the top cover forward and off. Apple's take-apart sequence then removes the drive mount before the logic board — and note that '''battery verification on this machine requires the cover and the drive mount to come out first''', which is why it is worth doing while you have the machine open for something else.<ref name="ss-ii" />

=== 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&nbsp;%) 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&nbsp;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]].

Apple's own SCSI notes for this chassis: the external device's ID switch must not be set to '''0''' (the internal drive) or '''7''' (the computer), and "drive icon does not appear on the desktop" and "data is lost or corrupted" both resolve to a termination check in Apple's symptom charts.<ref name="ss-ii" />

== Things that are not faults ==

* '''A system that shuts down intermittently after long use.''' Apple's first cure is to make sure the air vents on the sides and top are unobstructed, because the thermal protection circuitry may have shut the machine down — and it should be usable again after 30–40 minutes.<ref name="ss-ii" /> That is a designed behaviour, not a failure.
* '''8 MB reported with more fitted.''' The ROM is 32-bit dirty; see above.<ref name="everymac" />
* '''An MS-DOS drive refusing a disc formatted on the 1.4 MB drive.''' Apple's instruction is to format all such discs on the MS-DOS drive first.<ref name="ss-ii" />
* '''No built-in video.''' The IIx has none. A NuBus video card is not an upgrade, it is a requirement.<ref name="ss-ii" />

== 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.

== Service documentation ==

<pdf width="800" height="500">File:macintosh_ii.iix.iifx.pdf</pdf>

== Related pages ==
* [[Macintosh II]] — direct predecessor
* [[Macintosh IIfx]] — the fast member of the same chassis
* [[Macintosh IIcx]] — the compact three-slot version
* [[Macintosh IIci]] — built-in video and a 32-bit clean ROM
* [[Macintosh II/IIx/IIfx Service Source]]
* [[Capacitor Failure Symptoms]]
* [[Battery Explosion, Capacitor or Corrosion Damage]]
* [[Recommended Tools]]

== References ==
<references />

[[Category:Apple Vintage Computers]]
{{Navbox-AppleVintage|state=collapsed}}