Macintosh Performa 250 Troubleshooting
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The Macintosh Performa 250 is the Macintosh Color Classic sold under a Performa name, and Apple covers both in the same service manual.[1][2] The fuller guide is Macintosh Color Classic Troubleshooting; the table below gives Apple's own first steps from the Macintosh Color Classic Service Source, with cures in Apple's order of likelihood.
Mains voltage and the CRT's stored charge are present inside this machine. Discharge the CRT before touching the analogue board or the tube; see CRT Discharge Procedure.
Apple's symptom charts
[edit | edit source]| Symptom | Apple's cures, in order |
|---|---|
| No video, no sound, no drive activity | Connect the power cord; switch on; replace the power cord; replace the analogue board; replace the logic board (p. 35) |
| Screen black, too dark or too bright; sound and drive work | Adjust the contrast button; reset PRAM; check the yoke cable; perform the video adjustments; replace the analogue board; replace the CRT (p. 20) |
| Screen bright with sound, but no picture | Perform the video adjustments; replace the analogue board; replace the CRT (p. 20) |
| Thin grey horizontal line across the lower third of the screen | Not a fault: Apple says it is inherent in Trinitron tubes. "Do not replace modules." (p. 21) |
| Flashing or wavy screen, or a high-pitched noise | Replace the analogue board (p. 24) |
| Clicking, chirping or thumping | Check the logic board power cable at J12; replace the analogue board; replace the logic board (p. 35) |
| Smoke or smell | Replace the analogue board (p. 35) |
| Sad Mac icon | Try a known-good disk; replace the RAM SIMMs; replace the logic board (p. 36) |
| Hard drive does not work | Remove any SCSI loopback card; check the internal drive has all three terminating resistor packs; check external termination; replace the data cable; replace the drive; replace the logic board (p. 30) |
Apple's charts stop at module level. On a machine this age, leaking capacitors on the logic board and the analogue board, and a leaking PRAM battery, are the first suspects.
Notes
[edit | edit source]The logic board comes out of the back after removing the I/O door. After refitting it, check that no bent chassis tab can touch the underside of the board (PDF pp. 38–41).[2]
Apple's battery rule is to replace the cell below 3.0 V (PDF p. 94).[2] Neutralise lithium battery leakage with sodium bicarbonate, not vinegar. See Battery Explosion, Capacitor or Corrosion Damage.
A Sad Mac icon shows a code that identifies the failing test; decode it with Sad Mac Error Codes.
Related pages
[edit | edit source]- Macintosh Performa 250
- Macintosh Color Classic Troubleshooting
- Macintosh Color Classic General Maintenance
- Macintosh Color Classic Capacitor Replacement Guide
- Sad Mac Error Codes
References
[edit | edit source]- ↑ Low End Mac, "Apple's Performa Line, 1992 to 1997".
- ↑ 2.0 2.1 2.2 Apple Computer, Service Source: Macintosh Color Classic, Troubleshooting, PDF pp. 19–36, File:Color classic.pdf; see Macintosh Color Classic Service Source.