Editing Macintosh LC 575

{{Infobox computer
| name         = Macintosh LC 575
| image        = [[File:Macintosh LC 575.jpg|250px]]
| caption      = Macintosh LC 575
| manufacturer = Apple Computer, Inc.
| type         = All-in-one personal computer
| release date = 2 February 1994
| discontinued = 3 April 1995
| price        = US$1,700
| cpu          = Motorola 68LC040 @ 33 MHz
| memory       = 4 MB on board, expandable to 36 MB
| storage      = 160 MB or 320 MB SCSI hard drive; manual-insert 1.4 MB SuperDrive; optional 2x CD-ROM
| display      = 14 in Trinitron CRT, 13 in viewable, 640 x 480
| sound        = Stereo output, monaural input; 11/22 kHz record, 22 kHz playback
| dimensions   = 45.5 cm H x 34.4 cm W x 42.0 cm D (17.9 x 13.5 x 16.5 in)
| weight       = 18.4 kg (40.5 lb)
| os           = System 7.1 - Mac OS 8.1
| predecessor  = [[Macintosh LC 550]]
| successor    = [[Macintosh LC 580]]
| codename     = Optimus
| 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
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
specification gives 33 MHz; the 66 MHz figure is the oscillator feeding the processor, which is
not clock-doubled.<ref name="ss-520" /><ref name="everymac-575" />

== Model variants ==

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:

<templatestyles src="Template:StyledTable/styles.css" />
{| class="wikitable styled-table" style="width:80%;"
|+ Apple service parts, LC 520 / 550 / 575<ref name="ss-520" />
! Part !! Number
|-
| Logic board, LC 575 || 661-0867
|-
| Logic board, LC 550 || 661-1830
|-
| Logic board, LC 520 || 661-0812
|-
| Analogue board (all three models) || 661-0192
|-
| CRT || 661-1666; 661-1667 (Australia); 661-1668 (Europe)
|-
| Floppy drive, manual insert || 661-0121
|-
| CD-ROM drive || 661-0222
|-
| Fan || 922-1803
|-
| Internal microphone || 922-1802
|}

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
|-
| Raster width (HW) || 9 1/4 in ± 1/8 in (235 mm ± 2 mm) on an all-white screen
|-
| Vertical / horizontal centre (VS, HS) || Raster centred in the display area
|}

Cutoff and white balance are set on the Gray Bars pattern after the monitor has been on for at least ten
minutes, with contrast at maximum and the Screen control panel brightness at midrange. Cutoff is set
first, with VG2 adjusted until the first bar is completely black and the second is barely visible; white
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 ==

=== System ===

{| class="wikitable styled-table" style="width:90%;"
! Sub-system !! Specification
|-
| 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
SIMM.<ref name="ss-520" /> Third-party references commonly quote 80 ns as the requirement.<ref name="everymac-575" /> Faster is
always safe; the two figures do not agree and the discrepancy is noted here rather than resolved.

=== Memory configurations ===

The machine has 4 MB soldered and one SIMM socket, so the total is 4 MB plus whatever is in the
socket, to a maximum of 36 MB.<ref name="ss-520" /> Apple's standard configurations were 5 MB (a 1 MB
SIMM) and 8 MB (a 4 MB SIMM).<ref name="everymac-575" />

=== I/O ports ===

{| class="wikitable styled-table" style="width:90%;"
|+ From Apple's I/O Interfaces specification<ref name="ss-520" />
! 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
cards, and lists it as one of the three features that distinguish the LC 575 from the LC 520 and LC
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:80%;"
|+ 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)
|-
| Storage temperature || −40 to 149 °F (−40 to 65 °C)
|-
| Relative humidity || 20–95 %, non-condensing
|-
| Altitude || 0–10,000 ft operating
|}

== PRAM battery ==

Apple's specification for the LC 520/550/575 lists a long-life lithium battery, and Apple's service
check is to measure it on the 10 V DC range and replace it if it reads below '''3.0 V'''. On
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
pack.<ref name="everymac-575" /> Apple's own manual for this machine says lithium and gives a 3.0 V replacement
threshold, which does not fit a 4.5 V pack. Open the machine and look at what is actually fitted
before ordering a replacement — and measure it while it is in there.

Whatever is fitted, a cell left in a stored machine is one of the two great destroyers of boards of this
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.

== Related pages ==

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

== References ==
<references />

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