Jump to content

Macintosh LC 575: Difference between revisions

From RetroTechCollection
← Older edit

Josh (talk | contribs)

8 user groups
17,367 edits
undo
VisualWikitext
Retarget link to the kept page title after the duplicate-title pair was resolved
Remove Category:All-in-One Macintosh (created in error, to be deleted)
 
(3 intermediate revisions by the same user not shown)
Line 1: Line 1:
{{Infobox computer
{{Infobox computer
| name        = Macintosh LC 575
| name        = Macintosh LC 575
| image        = [[File:Macintosh LC 575.jpg|250px]]
| image        = [[File:Macintosh LC 575.jpg|250px|frameless]]
| caption      = Macintosh LC 575
| caption      = Macintosh LC 575
| manufacturer = Apple Computer, Inc.
| manufacturer = Apple Computer, Inc.
| type        = All-in-one personal computer
| type        = All-in-one personal computer
| release date = 2 February 1994
| release_date = 2 February 1994
| discontinued = 3 April 1995
| discontinued = 3 April 1995
| price        = US$1,700
| price        = US$1,700
| cpu          = Motorola 68LC040 @ 33 MHz
| cpu          = Motorola 68LC040 at 33 MHz (socketed; no FPU)
| memory      = 4 MB on board, expandable to 36 MB
| memory      = 4 MB on the logic board; one 72-pin SIMM socket; 36 MB maximum
| storage      = 160 MB or 320 MB SCSI hard drive; manual-insert 1.4 MB SuperDrive; optional 2x CD-ROM
| rom          = 1 MB, soldered
| display      = 14 in Trinitron CRT, 13 in viewable, 640 x 480
| graphics    = Two VRAM SIMM sockets, 512 KB or 1 MB
| sound        = Stereo output, monaural input; 11/22 kHz record, 22 kHz playback
| storage      = Internal 160 or 320 MB SCSI hard disk
| dimensions  = 45.5 cm H x 34.4 cm W x 42.0 cm D (17.9 x 13.5 x 16.5 in)
| media        = 1.4 MB Apple SuperDrive (manual-inject); AppleCD 300+ CD-ROM drive (tray)
| weight      = 18.4 kg (40.5 lb)
| display      = Built-in 14-inch Trinitron, 640 × 480
| os          = System 7.1 - Mac OS 8.1
| sound        = Stereo output, two speakers, front headphone jack; mono recording at 11 or 22 kHz; built-in microphone
| predecessor  = [[Macintosh LC 550]]
| expansion    = One LC-series expansion slot (96- or 114-pin cards); communications slot for a modem or Ethernet card
| ports        = ADB, two serial (mini DIN-8), SCSI (DB-25), sound in and out
| power        = 100-240 V AC, 47-63 Hz, 120 W maximum
| dimensions  = 17.9 × 13.5 × 16.5 in (45.5 × 34.4 × 42.0 cm)
| weight      = 40.5 lb (18.4 kg)
| os          = System 7.1 to Mac OS 8.1
| predecessor  = [[Macintosh LC 520]]
| successor    = [[Macintosh LC 580]]
| successor    = [[Macintosh LC 580]]
| codename    = Optimus
| codename    = Optimus
| model        = M1640
| model        = M1640
}}
}}
The '''Macintosh LC 575''' is an all-in-one Macintosh introduced on 2 February 1994 and discontinued on
3 April 1995.<ref name="everymac-575">[https://everymac.com/systems/apple/mac_lc/specs/mac_lc_575.html EveryMac.com — Apple Macintosh LC 575 Specs]. Third-party reference, used here for introduction and discontinuation dates, price, model and Gestalt identifiers, supported system software, and for the explanation of the 66 MHz figure sometimes quoted for this machine.</ref> It is the 68LC040 member of Apple's LC 500 series: the same chassis and the same
14-inch Trinitron display as the [[Macintosh LC 520|LC 520]] and [[Macintosh LC 550|LC 550]], with a
faster processor and one extra expansion slot.


Apple's identifying features for the LC 575, as against the LC 520 and LC 550, are precisely three: a
The '''Macintosh LC 575''' is an all-in-one Macintosh made by Apple Computer from February 1994 to April 1995. Apple describes it as the case and 14-inch Trinitron display of the [[Macintosh LC 520]] with the electrical design of the [[Macintosh LC 475]]: a 33 MHz 68LC040, the same custom chips and expansion slot, and a new communications slot for a modem or Ethernet card.<ref name="dn">Apple Computer, ''Macintosh LC 575 Computer Developer Note'' (1994), [[:File:Macintosh LC 575 Developer Note.pdf]]; see [[Macintosh LC 575 Developer Note]]. Printed pages: pp. 2-3 (features; Table 1-1, comparison with the LC 520 and LC 475); p. 4 (logic board access); p. 6 (power switch); pp. 7-8 (RAM); p. 12 (VRAM); p. 14 (SCSI termination); p. 17 (communications options; ADB); p. 21 (expansion slot); pp. 24-28 (processor and custom ICs); p. 34 (gestaltMachineType 92); p. 52 (power for the expansion card); p. 60 (power for the CD-ROM drive).</ref> Apple's service manual covers it with the LC 520 and [[Macintosh LC 550]].<ref name="ss">Apple Computer, ''Macintosh LC 520, LC 550, LC 575'' Service Source (1995), [[:File:Lc 520.550.575.pdf]]; see [[Macintosh LC 520/550/575 Service Source]]. PDF page numbers: Product Information pp. 4-5; Specifications pp. 7-17; Symptom Charts pp. 20-36; Rear Housing pp. 38-40; Analog Board pp. 43-48; Logic Board pp. 51-52; Macintosh Processor Upgrade pp. 99-122 (LC 520 and 550 PowerPC upgrade p. 101); Battery Verification and Replacement, LC 575, pp. 126-127 and 131-132; Adjustments pp. 134-174; Exploded View p. 176.</ref>
68LC040 processor, an additional communications slot, and a hook-and-loop-attached
battery.<ref name="ss-520">Apple Computer, ''Service Source: Macintosh LC 520, 550, 575'' — Basics, Specifications, Troubleshooting, Take Apart, Adjustments, Additional Procedures and Exploded View chapters. Hosted on this wiki as [[:File:Lc 520.550.575.pdf]]; see [[Macintosh LC 520/550/575 Service Source]].</ref> The LC 550 and LC 575 also share the newer manual-insert SuperDrive, a revised
chassis harness with no floppy drive adapter, and the caddyless CD 300+ CD-ROM drive.<ref name="ss-520" />


'''On the 66 MHz figure.''' The LC 575 is sometimes listed as a 66 MHz machine. Apple's own
== History ==
specification gives 33 MHz; the 66 MHz figure is the oscillator feeding the processor, which is
The LC 575 was introduced on 2 February 1994, alongside the LC 550, and discontinued on 3 April 1995; its codename was Optimus.<ref name="everymac">{{cite web |url=https://everymac.com/systems/apple/mac_lc/specs/mac_lc_575.html |title=Apple Macintosh LC 575 Specs |publisher=EveryMac |access-date=2026-09-30}} Introduced 2 February 1994, discontinued 3 April 1995; US$1,700; model M1640, Gestalt ID 92; 33 MHz 68LC040 (the 66 MHz sometimes quoted is the clock input; the processor is not clock-doubled); socketed, upgradable to a 68040 or PowerPC 601; 5 MB or 8 MB standard; System 7.1 to Mac OS 8.1.</ref><ref name="wp">{{cite web |url=https://en.wikipedia.org/wiki/Macintosh_LC_500_series |title=Macintosh LC 500 series |publisher=Wikipedia |access-date=2026-09-30}} Codename Optimus; Performa 575, 577 and 578 variants; succeeded by the LC 580 and the Power Macintosh 5200 LC.</ref> Apple's schematic for the logic board is titled "Optimus".<ref name="sch" /> It was also sold as the Performa 575, 577 and 578.<ref name="wp" /> The LC 575 is sometimes listed at 66 MHz; Apple gives 33 MHz, and EveryMac explains the higher figure as the clock input to a processor that is not clock-doubled.<ref name="ss" /><ref name="everymac" />
not clock-doubled.<ref name="ss-520" /><ref name="everymac-575" />


== Model variants ==
Apple's PowerPC upgrade for the LC 520 and LC 550 consisted of an LC 575 logic board, the PowerPC upgrade card, a new rear panel and an LC 575 product label.<ref name="ss" /> Recap-a-Mac notes that LC 575 logic boards are often removed and fitted into Color Classic cases (the "Mystic" upgrade).<ref name="ram">{{cite web |url=https://recapamac.com.au/macintosh-lc575/ |title=Macintosh LC575 |publisher=Recap-a-Mac |access-date=2026-09-30}} Annotated photograph of logic board 820-0464-B, hosted here as [[:File:Mac LC 575 Recap Guide.jpg]]: 10 × 47 µF 16 V and 2 × 100 µF 6.3 V; LC 575 boards are commonly transplanted into Color Classics (the "Mystic" upgrade).</ref>
 
The LC 575 was sold to education. The consumer equivalents are the Performa 575, 577 and 578. Apple's
own service documentation for this chassis family covers the LC 520, LC 550 and LC 575 together; the
Performa variants are the same machines with different bundles.<ref name="ss-520" />
 
Configurations quoted by Apple's Service Source are a 160 MB or 320 MB SCSI hard drive, with the
CD-ROM drive optional — an education configuration was sold without one.<ref name="ss-520" /><ref name="everymac-575" />
 
== General maintenance ==
 
The LC 575 is an all-in-one: mains-powered analogue board, CRT and logic board in one case. Before doing
anything inside it, read [[CRT Discharge Procedure]]. The anode holds a charge after the machine is
switched off and unplugged, and the analogue board carries mains voltage on its primary side. Both are
live at the same time when the case is open.
 
Routine care is the same as any beige Macintosh of the period: keep the vents clear, do not run it in a
sealed cabinet, check the PRAM battery every few years and take it out before storage, and clean the
front-panel contrast and volume buttons rather than forcing them. For yellowed plastics see
[[Retrobrite]]; for battery and electrolyte damage see
[[Battery Explosion, Capacitor or Corrosion Damage]].
 
== Logic board and service parts ==
 
The logic board is '''820-0464-B''' (copyright 1993, 1994).<ref name="ram-575">[https://recapamac.com.au/macintosh-lc575/ Recap-a-Mac — Macintosh LC575]. Annotated photograph of the 820-0464-B logic board. Hosted on this wiki as [[:File:Mac LC 575 Recap Guide.jpg]]. Secondary source.</ref> Apple's service part numbers for
this family are:


== Specifications ==
<templatestyles src="Template:StyledTable/styles.css" />
<templatestyles src="Template:StyledTable/styles.css" />
{| class="wikitable styled-table" style="width:80%;"
{| class="wikitable styled-table" style="width:88%;"
|+ Apple service parts, LC 520 / 550 / 575<ref name="ss-520" />
|+'''Macintosh LC 575 specifications (Apple)'''
! Part !! Number
! Item !! Specification
|-
|-
| Logic board, LC 575 || 661-0867
| Processor || Motorola 68LC040 at 33 MHz (no FPU), in a socket
|-
|-
| Logic board, LC 550 || 661-1830
| RAM || 4 MB on the board, expandable to 36 MB with one 72-pin SIMM
|-
|-
| Logic board, LC 520 || 661-0812
| ROM || 1 MB, soldered
|-
|-
| Analogue board (all three models) || 661-0192
| VRAM || Two 68-pin VRAM SIMM sockets, 512 KB or 1 MB; no VRAM on the board
|-
|-
| CRT || 661-1666; 661-1667 (Australia); 661-1668 (Europe)
| Floppy drive || Internal 1.4 MB Apple SuperDrive, manual-inject
|-
|-
| Floppy drive, manual insert || 661-0121
| Hard disk || 160 or 320 MB SCSI (Developer Note); 80, 160, 250 or 320 MB (Service Source)
|-
|-
| CD-ROM drive || 661-0222
| CD-ROM || AppleCD 300+ (tray-loading)
|-
|-
| Fan || 922-1803
| Expansion || One slot for 96-pin LC II or 114-pin LC III/LC 520 cards; communications slot for a modem or Ethernet card
|-
|-
| Internal microphone || 922-1802
| Sound || Records at 11 or 22 kHz, plays at 22 kHz; two speakers; stereo output jack and front headphone jack; mono input
|}
|-
 
| Display || 14-inch diagonal, 13-inch viewable Trinitron; 0.26 mm aperture grille pitch; 640 × 480 at 70 dpi
There is '''one''' analogue board part number for the whole family. Apple specifies the supply as
universal, 100–240 VAC at 47–63 Hz, so unlike some machines of this era there is no
separate 115 V and 230 V board to confuse when ordering parts or reading capacitor
lists.<ref name="ss-520" /> The CRT, by contrast, does have regional part numbers.
 
The board photograph below shows an AM53C96 SCSI controller and a Zilog Z8530 serial communications
controller alongside four Apple ASICs marked 343S0129-C, 343S0138-A, 343S0164-b and
343S1091-A.<ref name="ram-575" /> Apple's Service Source for this machine is module-level and does not describe what
those ASICs do, so this wiki does not claim to either.
 
=== Apple service manual ===
 
<pdf width="800" height="500">File:Lc 520.550.575.pdf</pdf>
 
Download the Macintosh LC 520/550/575 Service Source here: [[:File:Lc 520.550.575.pdf]]. Further
documentation is listed under [[:Category:Apple Service Source]].
 
=== Schematic ===
 
<pdf>File:LC575.pdf</pdf>
 
Download the Macintosh LC 575 schematic here: [[:File:LC575.pdf]]
 
== Capacitor replacement ==
 
The LC 575 logic board carries '''twelve surface-mount electrolytic capacitors''':
 
* '''10 × 47 µF 16 V'''
* '''2 × 100 µF 6.3 V'''
 
These figures come from Recap-a-Mac's annotated photograph of an 820-0464-B board, which is also the
location map — there is no second published list for this board to cross-check against, and Apple
never published component-level capacitor data for any Macintosh of this era.<ref name="ram-575" /> Read the value
printed on each capacitor body before you lift it.
 
[[File:Mac LC 575 Recap Guide.jpg|center|thumb|700px|Macintosh LC 575 logic board 820-0464-B, with each
electrolytic marked with its value, working voltage and positive terminal. Source: Recap-a-Mac.]]
 
Leaking SMD electrolytics on this generation show up first as lost or distorted sound, then as
intermittent starting, and finally as corroded copper under the solder mask. The removal and fitting
procedure is identical to the rest of the LC family and is documented on
[[Macintosh LC Capacitor Replacement Guide]]; see also [[Capacitor Failure Symptoms]].
 
The analogue board carries its own electrolytics, on a board that is mains-connected and shares a case
with a charged CRT. No published per-designator list for the 661-0192 analogue board was found while
this page was verified, so none is given here.
 
== Display adjustments ==
 
Apple's Adjustments chapter gives figures you can check with a ruler and the Display Service
Utility's test patterns.<ref name="ss-520" /> All of the adjustment controls are in the high-voltage area of the
analogue board; Apple specifies a short plastic hex-head tool and warns explicitly against metal
alignment tools.
 
{| class="wikitable styled-table" style="width:80%;"
|+ Apple geometry targets, LC 520/550/575<ref name="ss-520" />
! Adjustment !! Target
|-
|-
| Raster height (VH) || 7 in ± 1/8 in (176 mm ± 2 mm) on an all-white screen
| Power || 100-240 V AC universal supply; 47-63 Hz; 120 W maximum
|-
|-
| Raster width (HW) || 9 1/4 in ± 1/8 in (235 mm ± 2 mm) on an all-white screen
| Size and weight || 17.9 × 13.5 × 16.5 in (45.5 × 34.4 × 42.0 cm); 40.5 lb (18.4 kg)
|-
|-
| Vertical / horizontal centre (VS, HS) || Raster centred in the display area
| Environment || Operating 10-40 °C; storage −40 to 65 °C; 20-95 % relative humidity; up to 10,000 ft
|}
|}
From the Developer Note and the Service Source.<ref name="dn" /><ref name="ss" /> The Service Source asks for SIMMs of 100 ns or faster; the Developer Note asks for 80 ns or faster.<ref name="ss" /><ref name="dn" /> The Service Source lists two ADB ports for the three models; the Developer Note's comparison table gives the LC 575 one.<ref name="ss" /><ref name="dn" />


Cutoff and white balance are set on the Gray Bars pattern after the monitor has been on for at least ten
== Hardware ==
minutes, with contrast at maximum and the Screen control panel brightness at midrange. Cutoff is set
=== Logic board ===
first, with VG2 adjusted until the first bar is completely black and the second is barely visible; white
The logic board is Apple part 661-0867 and is printed "820-0464-B".<ref name="ss" /><ref name="ram" /> It slides out of the back after the connector cover is released with the two tabs above the ports.<ref name="dn" /> The custom chips are those of the LC 475: MEMCjr (memory and video controller), PrimeTime (I/O bus, SWIM II floppy controller, VIAs and sound buffers), DFAC II (sound conversion), Cuda (ADB, parameter RAM, clock and soft power) and Antelope (video CLUT and DAC).<ref name="dn" />
balance follows on the red, green and blue background and drive controls. Apple requires the cutoff
adjustment whenever the CRT or the analogue board is replaced.<ref name="ss-520" />


== Technical details ==
The 68LC040 is in a socket. Apple's Macintosh Processor Upgrade fits a PowerPC 601 card with a 256K cache card into that socket and carries the original 68LC040 in a socket of its own, so the machine can run on either processor.<ref name="ss" />


=== System ===
=== Memory and video ===
The board has 4 MB of RAM and one 72-pin SIMM socket for 1 to 32 MB SIMMs, giving 5 to 36 MB.<ref name="dn" /> All video memory is on two 68-pin VRAM SIMMs; both sockets must be filled, with SIMMs of the same size (256 KB or 512 KB each), for 512 KB or 1 MB.<ref name="dn" /> With 1 MB the built-in display runs at 16 bits per pixel.<ref name="ss" /> There is no external video connector.<ref name="dn" />


{| class="wikitable styled-table" style="width:90%;"
=== Communications slot ===
! Sub-system !! Specification
The LC 575 has a socket on the logic board for one of three communications cards: a modem, Ethernet with an AUI connector, or Ethernet with a 10BASE-T connector. Apple states that the socket is not a general expansion connector.<ref name="dn" /> The Service Source describes it as internal expansion for 50-pin modem and Ethernet cards.<ref name="ss" />
|-
| Processor || Motorola 68LC040, 33 MHz, built-in MMU, no FPU. Socket for an optional coprocessor<ref name="ss-520" />
|-
| Processor upgrade || Socketed; Apple's Macintosh Processor Upgrade fits a PowerPC 601 with a 256 K cache card and re-seats the customer's 68LC040 on the upgrade board<ref name="ss-520" />
|-
| ROM || 1 MB<ref name="ss-520" />
|-
| RAM || 4 MB on board, expandable to 36 MB through a single 72-pin SIMM socket<ref name="ss-520" />
|-
| PRAM || 256 bytes of clock/calendar/parameter memory<ref name="ss-520" />
|-
| VRAM || 512 K on board for 8-bit colour, expandable to 1 MB for 16-bit colour, across two VRAM SIMM slots<ref name="ss-520" />
|-
| Display || 14 in Trinitron with high-contrast glass, 13 in viewable, 0.26 mm aperture grille pitch, 640 x 480 at 70 dpi<ref name="ss-520" />
|-
| Sound || Stereo sound output port and front headphone jack; monaural sound input; records at 11 or 22 kHz, plays back at 22 kHz; two speakers; built-in electret omnidirectional microphone<ref name="ss-520" />
|-
| Storage || Manual-insert 1.4 MB SuperDrive; 3.5 in internal SCSI hard drive of 80, 160, 250 or 320 MB; internal Apple CD 300+ CD-ROM drive<ref name="ss-520" />
|-
| Expansion || One processor-direct slot taking 96-pin or 114-pin cards, plus a communications slot for 50-pin modem and Ethernet cards<ref name="ss-520" />
|-
| Gestalt ID || 92<ref name="everymac-575" />
|}


'''SIMM speed:''' Apple's LC 520/550/575 volume specifies "100 ns or faster" for the DRAM
=== Expansion slot ===
SIMM.<ref name="ss-520" /> Third-party references commonly quote 80 ns as the requirement.<ref name="everymac-575" /> Faster is
The expansion slot is the LC 475's: it takes 96-pin LC II cards and 114-pin LC III and LC 520 cards, but it is not connected directly to the 68LC040.<ref name="dn" /> A card may draw 800 mA at +5 V, 20 mA at −5 V and 200 mA at +12 V, 4 W in all.<ref name="dn" /> The CD-ROM drive is budgeted 500 mA at +5 V and 800 mA at +12 V (1.5 A peak).<ref name="dn" />
always safe; the two figures do not agree and the discrepancy is noted here rather than resolved.


=== Memory configurations ===
=== SCSI ===
The internal hard disk terminates the internal end of the SCSI bus.<ref name="dn" /> Apple's chart for a machine that works with the internal or an external device but not both checks that the external device's ID is above 0 and not duplicated, then the external terminator, then the SCSI cable.<ref name="ss" />


The machine has 4 MB soldered and one SIMM socket, so the total is 4 MB plus whatever is in the
=== Analog board, CRT and power ===
socket, to a maximum of 36 MB.<ref name="ss-520" /> Apple's standard configurations were 5 MB (a 1 MB
The power supply is on the analog board, Apple part 661-0192, shared with the LC 520 and LC 550, which also drives the CRT (661-1666; 661-1667 Australia, 661-1668 Europe).<ref name="ss" /> The supply is universal, 100-240 V AC, with no voltage selector.<ref name="ss" /> Apple gives no power-supply voltages or adjustment; its Adjustments chapter covers the display only. Remove the test jumper at BD11 on the analog board, if fitted: it makes the machine restart after shutdown.<ref name="ss" />
SIMM) and 8 MB (a 4 MB SIMM).<ref name="everymac-575" />


=== I/O ports ===
'''The analog board and CRT carry high voltage, and the CRT holds its charge after the machine is unplugged.''' Apple discharges the CRT and removes the anode cap before touching the analog board, and warns never to wear a grounding wrist strap until the CRT is discharged.<ref name="ss" /> See [[CRT Discharge Procedure]]. The take-apart sequence and Apple's geometry targets are on [[Macintosh LC 520]]; cutoff and white balance are set after at least 10 minutes' warm-up, cutoff first, and cutoff is repeated whenever the CRT or analog board is replaced.<ref name="ss" />


{| class="wikitable styled-table" style="width:90%;"
=== Battery ===
|+ From Apple's I/O Interfaces specification<ref name="ss-520" />
The LC 575's battery is on a connector and a hook-and-loop base on the logic board, not in a clip-in holder. To replace it, remove the I/O door and logic board, pull up and disconnect the connector, and pull the battery off its base. Apple's test is the same as for the LC 520: 10 V DC range, replace below 3.0 V.<ref name="ss" /> The BOM in Apple's Optimus schematic set lists the battery (BT1) as 742-0025, with 742-0011, a 3.6 V battery, as the alternative.<ref name="sch" /> Apple's technical specifications page for the LC 575 gives the battery type as 4.5 V alkaline, as does EveryMac.<ref name="apple575">Apple, [https://support.apple.com/en-us/112222 "Macintosh LC 575: Technical Specifications"] (Battery Type: 4.5V alkaline). Retrieved 2026-10-01.</ref><ref name="everymac" /> Check the cell fitted before cleaning up a leak: lithium residue is neutralised with bicarbonate of soda, alkaline residue with a weak acid such as vinegar. See [[Battery Explosion, Capacitor or Corrosion Damage]].
! Port !! Connector !! Notes
|-
| Serial x 2 || Mini-DIN-8 || RS-232 / RS-422
|-
| SCSI || DB-25 || Up to six external devices
|-
| Apple Desktop Bus || Mini-DIN-4 || Apple's specification for this family lists two ADB ports, a maximum of three ADB devices, and 500 mA maximum current draw (mouse 10 mA, keyboard 25 mA)
|-
| Sound output || 3.5 mm || Stereo; plus a stereo headphone jack on the front bezel
|-
| Sound input || 3.5 mm || Monaural
|}
 
=== Communications slot ===


Apple describes the communications slot simply as internal expansion for '''50-pin''' modem and Ethernet
=== Capacitors ===
cards, and lists it as one of the three features that distinguish the LC 575 from the LC 520 and LC
Apple's Optimus bill of materials (v4.1, 33 MHz) lists twelve surface-mount aluminium electrolytics and eight surface-mount tantalums on the logic board:<ref name="sch">Apple Computer, "Optimus EVT1 Logic Board Schematic" (OPTIMUS_V41, 15 sheets, 1993) with the Optimus Main Logic Board BOMs v4.1-25MHz, v4.1-33MHz and v4.1 (EVT3), [[:File:LC575.pdf]]. PDF pp. 1-15 schematic, pp. 16-24 BOMs. The 33 MHz BOM (PDF p. 19) gives C1, C4 100 µF 6.3 V and C2, C5, C8, C11, C12, C13, C15, C16, C17, C29 47 µF 16 V (126S1020, 126S4710, CAP_ELECSM_6MM); C3, C7, C25, C26 10 µF 16 V and C6, C9, C10, C14 3.3 µF 16 V tantalum; the EVT3 BOM (PDF p. 24) gives BT1 742-0025, alternative 742-0011 3.6 V. A pre-production (engineering validation) document; check against the board.</ref>
550.<ref name="ss-520" /> EveryMac records the LC 575 as the first LC-series model to carry one.<ref name="everymac-575" /> No
verified list of compatible cards and their Apple part numbers was found while this page was checked, so
none is given.


=== Electrical, physical and environmental ===
{| class="wikitable styled-table" style="width:85%; text-align:center;"
 
|+'''LC 575 logic board electrolytic capacitors (Apple Optimus BOM v4.1, 33 MHz)'''
{| class="wikitable styled-table" style="width:80%;"
! Designators !! Value !! Voltage !! Type
|+ Apple specification<ref name="ss-520" />
! Item !! Specification
|-
| Line voltage || 100–240 VAC, universal power supply
|-
| Frequency || 47–63 Hz, single phase
|-
| Maximum power || 120 W
|-
| Dimensions || 17.9 in (45.5 cm) H x 13.5 in (34.4 cm) W x 16.5 in (42.0 cm) D
|-
| Weight || 40.5 lb (18.4 kg)
|-
|-
| Operating temperature || 50–104 °F (10–40 °C)
| C1, C4 || 100 µF || 6.3 V || Aluminium electrolytic, SMD
|-
|-
| Storage temperature || −40 to 149 °F (−40 to 65 °C)
| C2, C5, C8, C11, C12, C13, C15, C16, C17, C29 || 47 µF || 16 V || Aluminium electrolytic, SMD
|-
|-
| Relative humidity || 20–95 %, non-condensing
| C3, C7, C25, C26 || 10 µF || 16 V || Tantalum, SMD
|-
|-
| Altitude || 0–10,000 ft operating
| C6, C9, C10, C14 || 3.3 µF || 16 V || Tantalum, SMD
|}
|}
The BOM is from the engineering-validation stage, but its electrolytic count matches the production board: Recap-a-Mac's photograph of 820-0464-B and MacDat's list both give ten 47 µF 16 V and two 100 µF 6.3 V.<ref name="ram" /><ref name="macdat">{{cite web |url=https://macdat.net/repair/cap_reference/apple/lc/lc575.php |title=Macintosh LC 575 Capacitor Reference |publisher=MacDat |access-date=2026-09-30}} Logic board: 2 × 100 µF 6.3 V, 10 × 47 µF 16 V, surface-mount; reference photograph.</ref> Apple gives no component values for the analog board. See [[Macintosh LC Capacitor Replacement Guide]] for the procedure and [[Capacitor Failure Symptoms]].


== PRAM battery ==
[[File:Mac LC 575 Recap Guide.jpg|center|thumb|600px|Macintosh LC 575 logic board 820-0464-B, with each electrolytic marked with its value, voltage and positive terminal. Source: Recap-a-Mac.]]


Apple's specification for the LC 520/550/575 lists a long-life lithium battery, and Apple's service
== Troubleshooting ==
check is to measure it on the 10 V DC range and replace it if it reads below '''3.0 V'''. On
Apple's symptom charts are shared with the LC 520 and LC 550; a selection is on [[Macintosh LC 520#Troubleshooting]]. A thin grey horizontal line across the lower third of a lit screen is part of the Trinitron design and not a fault, and a machine that restarts after shutdown has the BD11 test jumper fitted.<ref name="ss" /> The start-up tones and Sad Mac codes are on [[Sad Mac Error Codes]].
the LC 575 the battery is attached with hook-and-loop fastener rather than clipped into a holder, and
Apple's take-apart sequence removes the I/O door, the logic board and then the battery.<ref name="ss-520" />


'''There is a source conflict here.''' EveryMac lists the LC 575's battery as a 4.5 V alkaline
== Documentation ==
pack.<ref name="everymac-575" /> Apple's own manual for this machine says lithium and gives a 3.0 V replacement
* [[Macintosh LC 520/550/575 Service Source]]: Apple's service manual for the three models.<ref name="ss" />
threshold, which does not fit a 4.5 V pack. Open the machine and look at what is actually fitted
* [[Macintosh LC 575 Developer Note]]: Apple's 1994 hardware description.<ref name="dn" />
before ordering a replacement — and measure it while it is in there.
* [[:File:LC575.pdf]]: Apple's Optimus logic board schematic and bills of materials.<ref name="sch" />


Whatever is fitted, a cell left in a stored machine is one of the two great destroyers of boards of this
<pdf width="800" height="500">File:Lc 520.550.575.pdf</pdf>
age; the other is the capacitors. See
[[Battery Explosion, Capacitor or Corrosion Damage]] and [[Battery Refurbishment]].
 
== Software ==
 
Apple shipped the LC 575 with System 7.1. EveryMac records the supported range as System 7.1 to 7.5.1
and 7.5.3 to Mac OS 8.1.<ref name="everymac-575" />
 
== Known issues and quirks ==
 
* '''SMD capacitor leakage.''' Assume an un-recapped board needs it. See above.
* '''PRAM battery corrosion.''' As above.
* '''Trinitron damper wires.''' Two faint horizontal lines are visible across the screen on any
  aperture-grille tube. They are part of the tube's construction, not a fault.
* '''Heat.''' The logic board, the analogue board and a CRT share one sealed-ish case. Blocked vents are
  a real cause of intermittent faults on this chassis.
* '''The "Mystic" upgrade.''' The LC 575 logic board is widely transplanted into a
  [[Macintosh Color Classic]] case by enthusiasts. Apple did something similar itself: its own PowerPC
  upgrade for the LC 520 and LC 550 consists of an LC 575 logic board, the PowerPC Upgrade Card, a new
  rear panel and a 575 product ID label.<ref name="ss-520" /> This is the main reason bare LC 575 boards are scarce
  and complete machines are often found gutted.
 
== Service documentation ==
 
Apple's own service manual is hosted here as [[Macintosh LC 520/550/575 Service Source]]. It
gives a '''universal 100–240 VAC supply''' at 47–63 Hz drawing '''120 W''' maximum and the PRAM cell
threshold as '''replace below 3.0 V''', and prints a '''battery verification and replacement
procedure specific to the LC 575''' — following the LC 520 steps on a 575 sends you to the wrong part
of the chassis.<ref name="ssmacintoshlc52055">Apple Computer, ''Macintosh LC 520/550/575'', Service Source, 176 pp, PDF distilled 5 December 1995. Hosted here as the wiki page linked above ([[:File:Lc 520.550.575.pdf]]). Specifications chapter, and Additional Procedures — Battery Verification where a threshold is quoted.</ref>


The higher-performance development of this machine, the LC 580, has its own volume:
<pdf width="800" height="500">File:LC575.pdf</pdf>
[[Macintosh LC 580/Performa 580CD Service Source]].<ref name="ssmacintoshlc52055" />


== Related pages ==
== Related pages ==
* [[Macintosh LC 520]]
* [[Macintosh LC 520]]
* [[Macintosh LC 550]]
* [[Macintosh LC 550]]
* [[Macintosh LC 580]]
* [[Macintosh LC 580]]
* [[Macintosh LC 475]] and [[Macintosh Quadra 605]] — the same processor in the pizza-box chassis
* [[Macintosh LC 475]]
* [[Macintosh LC Capacitor Replacement Guide]] — shared recapping procedure
* [[Macintosh Color Classic]]
* [[Macintosh LC 520/550/575 Service Source]]
* [[Macintosh Processor Upgrade Service Source]]
* [[CRT Discharge Procedure]]
* [[CRT Discharge Procedure]]
* [[Retrobrite]]
* [[Macintosh LC Capacitor Replacement Guide]]


== References ==
== References ==
<references />
<references />


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

Latest revision as of 18:42, 1 October 2026

Macintosh LC 575
Macintosh LC 575
Specifications
ManufacturerApple Computer, Inc.
TypeAll-in-one personal computer
Released2 February 1994
Discontinued3 April 1995
Intro priceUS$1,700
CPUMotorola 68LC040 at 33 MHz (socketed; no FPU)
Memory4 MB on the logic board; one 72-pin SIMM socket; 36 MB maximum
StorageInternal 160 or 320 MB SCSI hard disk
DisplayBuilt-in 14-inch Trinitron, 640 × 480
SoundStereo output, two speakers, front headphone jack; mono recording at 11 or 22 kHz; built-in microphone
GraphicsTwo VRAM SIMM sockets, 512 KB or 1 MB
ROM1 MB, soldered
Media1.4 MB Apple SuperDrive (manual-inject); AppleCD 300+ CD-ROM drive (tray)
Ports / interfaceADB, two serial (mini DIN-8), SCSI (DB-25), sound in and out
ExpansionOne LC-series expansion slot (96- or 114-pin cards); communications slot for a modem or Ethernet card
Power100-240 V AC, 47-63 Hz, 120 W maximum
Dimensions17.9 × 13.5 × 16.5 in (45.5 × 34.4 × 42.0 cm)
Weight40.5 lb (18.4 kg)
OS / FirmwareSystem 7.1 to Mac OS 8.1
PredecessorMacintosh LC 520
SuccessorMacintosh LC 580
CodenameOptimus
Model no.M1640

The Macintosh LC 575 is an all-in-one Macintosh made by Apple Computer from February 1994 to April 1995. Apple describes it as the case and 14-inch Trinitron display of the Macintosh LC 520 with the electrical design of the Macintosh LC 475: a 33 MHz 68LC040, the same custom chips and expansion slot, and a new communications slot for a modem or Ethernet card.[1] Apple's service manual covers it with the LC 520 and Macintosh LC 550.[2]

History

[edit | edit source]

The LC 575 was introduced on 2 February 1994, alongside the LC 550, and discontinued on 3 April 1995; its codename was Optimus.[3][4] Apple's schematic for the logic board is titled "Optimus".[5] It was also sold as the Performa 575, 577 and 578.[4] The LC 575 is sometimes listed at 66 MHz; Apple gives 33 MHz, and EveryMac explains the higher figure as the clock input to a processor that is not clock-doubled.[2][3]

Apple's PowerPC upgrade for the LC 520 and LC 550 consisted of an LC 575 logic board, the PowerPC upgrade card, a new rear panel and an LC 575 product label.[2] Recap-a-Mac notes that LC 575 logic boards are often removed and fitted into Color Classic cases (the "Mystic" upgrade).[6]

Specifications

[edit | edit source]
Macintosh LC 575 specifications (Apple)
Item Specification
Processor Motorola 68LC040 at 33 MHz (no FPU), in a socket
RAM 4 MB on the board, expandable to 36 MB with one 72-pin SIMM
ROM 1 MB, soldered
VRAM Two 68-pin VRAM SIMM sockets, 512 KB or 1 MB; no VRAM on the board
Floppy drive Internal 1.4 MB Apple SuperDrive, manual-inject
Hard disk 160 or 320 MB SCSI (Developer Note); 80, 160, 250 or 320 MB (Service Source)
CD-ROM AppleCD 300+ (tray-loading)
Expansion One slot for 96-pin LC II or 114-pin LC III/LC 520 cards; communications slot for a modem or Ethernet card
Sound Records at 11 or 22 kHz, plays at 22 kHz; two speakers; stereo output jack and front headphone jack; mono input
Display 14-inch diagonal, 13-inch viewable Trinitron; 0.26 mm aperture grille pitch; 640 × 480 at 70 dpi
Power 100-240 V AC universal supply; 47-63 Hz; 120 W maximum
Size and weight 17.9 × 13.5 × 16.5 in (45.5 × 34.4 × 42.0 cm); 40.5 lb (18.4 kg)
Environment Operating 10-40 °C; storage −40 to 65 °C; 20-95 % relative humidity; up to 10,000 ft

From the Developer Note and the Service Source.[1][2] The Service Source asks for SIMMs of 100 ns or faster; the Developer Note asks for 80 ns or faster.[2][1] The Service Source lists two ADB ports for the three models; the Developer Note's comparison table gives the LC 575 one.[2][1]

Hardware

[edit | edit source]

Logic board

[edit | edit source]

The logic board is Apple part 661-0867 and is printed "820-0464-B".[2][6] It slides out of the back after the connector cover is released with the two tabs above the ports.[1] The custom chips are those of the LC 475: MEMCjr (memory and video controller), PrimeTime (I/O bus, SWIM II floppy controller, VIAs and sound buffers), DFAC II (sound conversion), Cuda (ADB, parameter RAM, clock and soft power) and Antelope (video CLUT and DAC).[1]

The 68LC040 is in a socket. Apple's Macintosh Processor Upgrade fits a PowerPC 601 card with a 256K cache card into that socket and carries the original 68LC040 in a socket of its own, so the machine can run on either processor.[2]

Memory and video

[edit | edit source]

The board has 4 MB of RAM and one 72-pin SIMM socket for 1 to 32 MB SIMMs, giving 5 to 36 MB.[1] All video memory is on two 68-pin VRAM SIMMs; both sockets must be filled, with SIMMs of the same size (256 KB or 512 KB each), for 512 KB or 1 MB.[1] With 1 MB the built-in display runs at 16 bits per pixel.[2] There is no external video connector.[1]

Communications slot

[edit | edit source]

The LC 575 has a socket on the logic board for one of three communications cards: a modem, Ethernet with an AUI connector, or Ethernet with a 10BASE-T connector. Apple states that the socket is not a general expansion connector.[1] The Service Source describes it as internal expansion for 50-pin modem and Ethernet cards.[2]

Expansion slot

[edit | edit source]

The expansion slot is the LC 475's: it takes 96-pin LC II cards and 114-pin LC III and LC 520 cards, but it is not connected directly to the 68LC040.[1] A card may draw 800 mA at +5 V, 20 mA at −5 V and 200 mA at +12 V, 4 W in all.[1] The CD-ROM drive is budgeted 500 mA at +5 V and 800 mA at +12 V (1.5 A peak).[1]

SCSI

[edit | edit source]

The internal hard disk terminates the internal end of the SCSI bus.[1] Apple's chart for a machine that works with the internal or an external device but not both checks that the external device's ID is above 0 and not duplicated, then the external terminator, then the SCSI cable.[2]

Analog board, CRT and power

[edit | edit source]

The power supply is on the analog board, Apple part 661-0192, shared with the LC 520 and LC 550, which also drives the CRT (661-1666; 661-1667 Australia, 661-1668 Europe).[2] The supply is universal, 100-240 V AC, with no voltage selector.[2] Apple gives no power-supply voltages or adjustment; its Adjustments chapter covers the display only. Remove the test jumper at BD11 on the analog board, if fitted: it makes the machine restart after shutdown.[2]

The analog board and CRT carry high voltage, and the CRT holds its charge after the machine is unplugged. Apple discharges the CRT and removes the anode cap before touching the analog board, and warns never to wear a grounding wrist strap until the CRT is discharged.[2] See CRT Discharge Procedure. The take-apart sequence and Apple's geometry targets are on Macintosh LC 520; cutoff and white balance are set after at least 10 minutes' warm-up, cutoff first, and cutoff is repeated whenever the CRT or analog board is replaced.[2]

Battery

[edit | edit source]

The LC 575's battery is on a connector and a hook-and-loop base on the logic board, not in a clip-in holder. To replace it, remove the I/O door and logic board, pull up and disconnect the connector, and pull the battery off its base. Apple's test is the same as for the LC 520: 10 V DC range, replace below 3.0 V.[2] The BOM in Apple's Optimus schematic set lists the battery (BT1) as 742-0025, with 742-0011, a 3.6 V battery, as the alternative.[5] Apple's technical specifications page for the LC 575 gives the battery type as 4.5 V alkaline, as does EveryMac.[7][3] Check the cell fitted before cleaning up a leak: lithium residue is neutralised with bicarbonate of soda, alkaline residue with a weak acid such as vinegar. See Battery Explosion, Capacitor or Corrosion Damage.

Capacitors

[edit | edit source]

Apple's Optimus bill of materials (v4.1, 33 MHz) lists twelve surface-mount aluminium electrolytics and eight surface-mount tantalums on the logic board:[5]

LC 575 logic board electrolytic capacitors (Apple Optimus BOM v4.1, 33 MHz)
Designators Value Voltage Type
C1, C4 100 µF 6.3 V Aluminium electrolytic, SMD
C2, C5, C8, C11, C12, C13, C15, C16, C17, C29 47 µF 16 V Aluminium electrolytic, SMD
C3, C7, C25, C26 10 µF 16 V Tantalum, SMD
C6, C9, C10, C14 3.3 µF 16 V Tantalum, SMD

The BOM is from the engineering-validation stage, but its electrolytic count matches the production board: Recap-a-Mac's photograph of 820-0464-B and MacDat's list both give ten 47 µF 16 V and two 100 µF 6.3 V.[6][8] Apple gives no component values for the analog board. See Macintosh LC Capacitor Replacement Guide for the procedure and Capacitor Failure Symptoms.

Macintosh LC 575 logic board 820-0464-B, with each electrolytic marked with its value, voltage and positive terminal. Source: Recap-a-Mac.

Troubleshooting

[edit | edit source]

Apple's symptom charts are shared with the LC 520 and LC 550; a selection is on Macintosh LC 520#Troubleshooting. A thin grey horizontal line across the lower third of a lit screen is part of the Trinitron design and not a fault, and a machine that restarts after shutdown has the BD11 test jumper fitted.[2] The start-up tones and Sad Mac codes are on Sad Mac Error Codes.

Documentation

[edit | edit source]

[edit | edit source]

References

[edit | edit source]
  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 Apple Computer, Macintosh LC 575 Computer Developer Note (1994), File:Macintosh LC 575 Developer Note.pdf; see Macintosh LC 575 Developer Note. Printed pages: pp. 2-3 (features; Table 1-1, comparison with the LC 520 and LC 475); p. 4 (logic board access); p. 6 (power switch); pp. 7-8 (RAM); p. 12 (VRAM); p. 14 (SCSI termination); p. 17 (communications options; ADB); p. 21 (expansion slot); pp. 24-28 (processor and custom ICs); p. 34 (gestaltMachineType 92); p. 52 (power for the expansion card); p. 60 (power for the CD-ROM drive).
  2. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 2.18 Apple Computer, Macintosh LC 520, LC 550, LC 575 Service Source (1995), File:Lc 520.550.575.pdf; see Macintosh LC 520/550/575 Service Source. PDF page numbers: Product Information pp. 4-5; Specifications pp. 7-17; Symptom Charts pp. 20-36; Rear Housing pp. 38-40; Analog Board pp. 43-48; Logic Board pp. 51-52; Macintosh Processor Upgrade pp. 99-122 (LC 520 and 550 PowerPC upgrade p. 101); Battery Verification and Replacement, LC 575, pp. 126-127 and 131-132; Adjustments pp. 134-174; Exploded View p. 176.
  3. ↑ 3.0 3.1 3.2 Apple Macintosh LC 575 Specs, EveryMac—link(accessed 2026-09-30) Introduced 2 February 1994, discontinued 3 April 1995; US$1,700; model M1640, Gestalt ID 92; 33 MHz 68LC040 (the 66 MHz sometimes quoted is the clock input; the processor is not clock-doubled); socketed, upgradable to a 68040 or PowerPC 601; 5 MB or 8 MB standard; System 7.1 to Mac OS 8.1.
  4. ↑ 4.0 4.1 Macintosh LC 500 series, Wikipedia—link(accessed 2026-09-30) Codename Optimus; Performa 575, 577 and 578 variants; succeeded by the LC 580 and the Power Macintosh 5200 LC.
  5. ↑ 5.0 5.1 5.2 5.3 Apple Computer, "Optimus EVT1 Logic Board Schematic" (OPTIMUS_V41, 15 sheets, 1993) with the Optimus Main Logic Board BOMs v4.1-25MHz, v4.1-33MHz and v4.1 (EVT3), File:LC575.pdf. PDF pp. 1-15 schematic, pp. 16-24 BOMs. The 33 MHz BOM (PDF p. 19) gives C1, C4 100 µF 6.3 V and C2, C5, C8, C11, C12, C13, C15, C16, C17, C29 47 µF 16 V (126S1020, 126S4710, CAP_ELECSM_6MM); C3, C7, C25, C26 10 µF 16 V and C6, C9, C10, C14 3.3 µF 16 V tantalum; the EVT3 BOM (PDF p. 24) gives BT1 742-0025, alternative 742-0011 3.6 V. A pre-production (engineering validation) document; check against the board.
  6. ↑ 6.0 6.1 6.2 Macintosh LC575, Recap-a-Mac—link(accessed 2026-09-30) Annotated photograph of logic board 820-0464-B, hosted here as File:Mac LC 575 Recap Guide.jpg: 10 × 47 µF 16 V and 2 × 100 µF 6.3 V; LC 575 boards are commonly transplanted into Color Classics (the "Mystic" upgrade).
  7. ↑ Apple, "Macintosh LC 575: Technical Specifications" (Battery Type: 4.5V alkaline). Retrieved 2026-10-01.
  8. ↑ Macintosh LC 575 Capacitor Reference, MacDat—link(accessed 2026-09-30) Logic board: 2 × 100 µF 6.3 V, 10 × 47 µF 16 V, surface-mount; reference photograph.


Retrieved from "https://wiki.retrotechcollection.com/index.php?title=Macintosh_LC_575&oldid=20156"