Macintosh Quadra 605 Troubleshooting: Difference between revisions

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See [[Macintosh Quadra 605 Capacitor Replacement Guide]] for replacement procedures.

== ⚠️ PRAM battery — remove it now ==

The Macintosh Quadra 605 uses a 3.6 V 1/2AA lithium PRAM battery (often a red Maxell). These are notorious for '''leaking and even exploding''', spraying corrosive electrolyte across the logic board — a battery can burst while the machine sits in storage and destroy the board. '''Remove the PRAM battery from any un-serviced unit immediately.''' If one has leaked, neutralise and clean the residue and check the traces and vias around the battery and the nearby chips for corrosion, repairing any that are damaged.<ref name="lc_batt">[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 exploding/leaking Maxell PRAM battery and the resulting board damage, and the LC not booting without a battery.</ref>

The LC-series machines are also well known for '''not booting without a healthy PRAM battery'''. A dead or removed cell can leave the machine apparently dead or refusing to chime, so fit a fresh battery (or a modern coin-cell replacement) when testing.<ref name="lc_batt">[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 exploding/leaking Maxell PRAM battery and the resulting board damage, and the LC not booting without a battery.</ref>

== ⚠️ Surface-mount capacitor leakage ==

The Macintosh Quadra 605 logic board uses surface-mount electrolytic capacitors that leak electrolyte from the bottom with age. The leakage corrodes traces and vias and is a leading cause of faults, so '''recap and clean the board''' as a first step. A common pattern is a board that '''chimes but shows no video''' after servicing — usually corrosion damage (broken traces or vias) around the leaked capacitors (for example near C136/C137), which must be traced and repaired.<ref name="lc_cap">[https://quagmirerepair.com/quadra605 "Quadra 605 / LC 475"], Quagmire Repair; the Apple Macintosh LC/LC II/LC III/LC 475/Quadra 605 Service Source; and [https://pappp.net/?p=1530 "Macintosh LC Recap"], PAPPP's Rambling. Source for the SMD-capacitor leakage, the PSU recap, and the trace/via damage causing chime-but-no-video.</ref>

== Power supply ==

The compact LC "pizza-box" power supply also uses electrolytics that leak with age. A '''dead LC PSU can usually be revived by replacing all its electrolytic capacitors''' and cleaning the leakage; any working LC PSU should be recapped pre-emptively, as it will otherwise fail. Confirm the +5 V and +12 V rails after servicing.<ref name="lc_cap">[https://quagmirerepair.com/quadra605 "Quadra 605 / LC 475"], Quagmire Repair; the Apple Macintosh LC/LC II/LC III/LC 475/Quadra 605 Service Source; and [https://pappp.net/?p=1530 "Macintosh LC Recap"], PAPPP's Rambling. Source for the SMD-capacitor leakage, the PSU recap, and the trace/via damage causing chime-but-no-video.</ref>

== Processor and expansion ==

The LC 475 uses a 25 MHz Motorola '''68LC040''' (no FPU); a full 68040 can be fitted to add hardware floating-point. The 114-pin PDS expansion slot accepts LC-compatible I/O, display, network and video-capture cards. The '''[[Macintosh Quadra 605]]''' is the same logic board sold under the Quadra name.<ref name="lc_cap">[https://quagmirerepair.com/quadra605 "Quadra 605 / LC 475"], Quagmire Repair; the Apple Macintosh LC/LC II/LC III/LC 475/Quadra 605 Service Source; and [https://pappp.net/?p=1530 "Macintosh LC Recap"], PAPPP's Rambling. Source for the SMD-capacitor leakage, the PSU recap, and the trace/via damage causing chime-but-no-video.</ref>

== References ==

== Related Pages ==

@@ Line 199: / Line 199: @@
 See [[Macintosh Quadra 605 Capacitor Replacement Guide]] for replacement procedures.
+== ⚠️ PRAM battery — remove it now ==
+The Macintosh Quadra 605 uses a 3.6&nbsp;V 1/2AA lithium PRAM battery (often a red Maxell). These are notorious for '''leaking and even exploding''', spraying corrosive electrolyte across the logic board &mdash; a battery can burst while the machine sits in storage and destroy the board. '''Remove the PRAM battery from any un-serviced unit immediately.''' If one has leaked, neutralise and clean the residue and check the traces and vias around the battery and the nearby chips for corrosion, repairing any that are damaged.<ref name="lc_batt">[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 exploding/leaking Maxell PRAM battery and the resulting board damage, and the LC not booting without a battery.</ref>
+The LC-series machines are also well known for '''not booting without a healthy PRAM battery'''. A dead or removed cell can leave the machine apparently dead or refusing to chime, so fit a fresh battery (or a modern coin-cell replacement) when testing.<ref name="lc_batt">[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 exploding/leaking Maxell PRAM battery and the resulting board damage, and the LC not booting without a battery.</ref>
+== ⚠️ Surface-mount capacitor leakage ==
+The Macintosh Quadra 605 logic board uses surface-mount electrolytic capacitors that leak electrolyte from the bottom with age. The leakage corrodes traces and vias and is a leading cause of faults, so '''recap and clean the board''' as a first step. A common pattern is a board that '''chimes but shows no video''' after servicing &mdash; usually corrosion damage (broken traces or vias) around the leaked capacitors (for example near C136/C137), which must be traced and repaired.<ref name="lc_cap">[https://quagmirerepair.com/quadra605 "Quadra 605 / LC 475"], Quagmire Repair; the Apple Macintosh LC/LC&nbsp;II/LC&nbsp;III/LC&nbsp;475/Quadra&nbsp;605 Service Source; and [https://pappp.net/?p=1530 "Macintosh LC Recap"], PAPPP's Rambling. Source for the SMD-capacitor leakage, the PSU recap, and the trace/via damage causing chime-but-no-video.</ref>
+== Power supply ==
+The compact LC "pizza-box" power supply also uses electrolytics that leak with age. A '''dead LC PSU can usually be revived by replacing all its electrolytic capacitors''' and cleaning the leakage; any working LC PSU should be recapped pre-emptively, as it will otherwise fail. Confirm the +5&nbsp;V and +12&nbsp;V rails after servicing.<ref name="lc_cap">[https://quagmirerepair.com/quadra605 "Quadra 605 / LC 475"], Quagmire Repair; the Apple Macintosh LC/LC&nbsp;II/LC&nbsp;III/LC&nbsp;475/Quadra&nbsp;605 Service Source; and [https://pappp.net/?p=1530 "Macintosh LC Recap"], PAPPP's Rambling. Source for the SMD-capacitor leakage, the PSU recap, and the trace/via damage causing chime-but-no-video.</ref>
+== Processor and expansion ==
+The LC 475 uses a 25&nbsp;MHz Motorola '''68LC040''' (no FPU); a full 68040 can be fitted to add hardware floating-point. The 114-pin PDS expansion slot accepts LC-compatible I/O, display, network and video-capture cards. The '''[[Macintosh Quadra 605]]''' is the same logic board sold under the Quadra name.<ref name="lc_cap">[https://quagmirerepair.com/quadra605 "Quadra 605 / LC 475"], Quagmire Repair; the Apple Macintosh LC/LC&nbsp;II/LC&nbsp;III/LC&nbsp;475/Quadra&nbsp;605 Service Source; and [https://pappp.net/?p=1530 "Macintosh LC Recap"], PAPPP's Rambling. Source for the SMD-capacitor leakage, the PSU recap, and the trace/via damage causing chime-but-no-video.</ref>
+== References ==
+<references />
 == Related Pages ==