Macintosh LC 630 DOS Compatible Troubleshooting: Difference between revisions

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+[[File:Macintosh LC 630 DOS Compatible (photo).jpg|thumb|right|300px|Macintosh LC 630 DOS Compatible. Source: Wikimedia Commons.]]
 The '''Macintosh LC 630 DOS Compatible''' is a [[Macintosh LC 630]] fitted with a DOS-compatibility card (a 486 processor on a card, sharing the Mac's drives and display). The Macintosh side is electrically identical to the standard LC 630, so the '''[[Macintosh LC 630 Troubleshooting]]''' page applies in full for the Mac hardware.<ref name="lc630">Apple Service Source and Low End Mac, LC 630 / Quadra 630 family. Source for the LC 630 DOS Compatible configuration.</ref>
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 As with the LC 630, check the '''PRAM battery''' for leakage and corrosion, '''recap''' where needed, and confirm the power-supply rails. Full detail is on '''[[Macintosh LC 630 Troubleshooting]]'''.
+== Component-level faults (deep dive) ==
+=== Surface-mount capacitor leakage ===
+The Macintosh LC 630 DOS Compatible 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 LC 630 DOS Compatible 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 ==