Macintosh Classic / Classic II Troubleshooting: Difference between revisions
Expand troubleshooting: add common faults (RIFA/PRAM battery/recap/ROM-disk/SCSI), cited from 68kMLA/recapamac/etc. |
Removed unsourced rail tolerance figures (+5V 4.90-5.10, +12V 11.9-12.7): Apple's Classic/Classic II Service Source publishes no rail voltages. Replaced with Apple's actual Electrical spec and a sourced +-5% logic-supply check |
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Begin by confirming power output from the analog board. Use a multimeter to check voltage at the floppy or SCSI power connector: | Begin by confirming power output from the analog board. Use a multimeter to check voltage at the floppy or SCSI power connector: | ||
* '''+5V rail''': | Apple publishes no rail voltages or tolerances for this machine — the Electrical specification in the ''Macintosh Classic / Classic II / Performa 200 Service Source'' covers only the mains side (100–120 V AC, 47–63 Hz single phase, 100 W maximum). The useful test is whether the rails are inside the range the board's 5 V logic is specified for, which is 5 V ±5 per cent: | ||
* '''+12V rail''': | |||
* '''+5V rail''': '''4.75 V to 5.25 V''' | |||
* '''+12V rail''': steady, and free of visible ripple under load — Apple gives no figure for it | |||
If there are no signs of life (no fan, CRT glow, or chime), check the following: | If there are no signs of life (no fan, CRT glow, or chime), check the following: | ||