Macintosh LC Troubleshooting: Difference between revisions
Collapse duplicated <ref name=...> definitions to one definition with the rest self-closing (duplicate definitions render as a visible red cite error) |
DELETED the '+5 V 4.85-5.15 V / +12 V 11.9-12.7 V' rail table: that pair is Apple's Macintosh Plus and 128K/512K voltage-adjustment specification, measured at the external drive port with cable 077-0135 and with an upper bound of 12.75 V rather than 12.7, and the service volume covering this machine has no Adjustments chapter and no rail tolerances at all; replaced with Apple's own statement of what is and is not published, plus the replace-below-3.0 V battery threshold and bicarbonate rather... |
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=== | === What Apple publishes about the rails === | ||
'''Apple publishes no rail tolerance and no power-supply adjustment for the Macintosh LC.''' The service volume that covers it has '''no Adjustments chapter at all''' — these are monitorless machines, with nothing in them to adjust.<ref name="sslcs">Apple Computer, ''Macintosh LC Series/Quadra 605 Service Source'' ([[Macintosh LC Series/ Quadra 605 Service Source]], [[:File:Quadra_605.lc_series.pdf]]). This volume has no Adjustments chapter, so Apple publishes no rail tolerance and no power-supply adjustment for any LC. Battery Replacement: below 3.0 volts, replace the battery.</ref> | |||
'''The table previously here was another machine's.''' It gave "+5 V rail: 4.85 V – 5.15 V" and "+12 V rail: 11.9 V – 12.7 V". That pair is Apple's '''Macintosh Plus and 128K/512K''' voltage-adjustment specification, measured at the '''external drive port''' with voltage test cable '''077-0135''' — and Apple's upper bound there is '''12.75 V''', not 12.7. It has been copied across this wiki onto machines whose manuals contain no voltage procedure, and it told the reader to judge a good supply against a band nobody published for it. | |||
What to do instead: measure each rail at the logic board connector against its '''nominal''' value, look at the ripple, and check the machine holds them under load. A rail materially off nominal is a fault to find. | |||
Out-of-spec voltages indicate power supply problems. | Out-of-spec voltages indicate power supply problems. | ||