Macintosh Plus Troubleshooting: Difference between revisions

Line 109:

| 10–100µF electrolytics || Random resets, noise, video flicker || Replace with modern electrolytics of equal or higher voltage.

|}

== ⚠️ RIFA mains filter capacitor (smoke) ==

The Macintosh Plus power supply contains a '''RIFA''' paper/film mains-suppression capacitor that cracks with age and fails by emitting acrid smoke shortly after power-on. This is one of the most common Plus faults. Replace the RIFA X2 capacitor pre-emptively with a modern X2-class part (a few-minute through-hole job); do '''not''' keep running the machine once it has smoked.<ref name="plus_rifa">[https://www.crackedthecode.co/replacing-failed-capacitors-in-a-macintosh-computer/ "Vintage Computer Up In Smoke"], Cracked the Code; and [https://recapamac.com.au/macintosh-plus/ Macintosh Plus], Recap-a-Mac. Source for the RIFA mains-filter failure, the leaking alkaline PRAM battery, the cracked analog-board solder joints and the recap.</ref>

== ⚠️ PRAM battery leakage ==

The Plus uses an alkaline PRAM battery behind a door on the rear of the case. These leak badly, and the electrolyte runs down onto the analog board and corrodes it. Remove the battery on any un-serviced Plus and clean/repair any corrosion.<ref name="plus_rifa" />

== No video from cracked analog joints ==

The Plus commonly develops cracked solder joints on the larger analog-board components and connectors from heat cycling, giving a "no video" fault with the machine otherwise alive. Reflow the analog-board solder joints, especially around the deflection-yoke and flyback area and the analog-to-logic harness.<ref name="plus_rifa" />

== SCSI and RAM ==

The Plus was the first Macintosh with built-in SCSI (NCR 53C80). Period SCSI drives are commonly dead; fit a '''BlueSCSI''' or '''SCSI2SD''', and note that some SCSI adapters need termination power (TERMPWR) added at the connector on the Plus.<ref name="plus_rifa" /> RAM is four 30-pin SIMMs (256 KB or 1 MB SIMMs giving 512 KB, 1 MB, 2 MB or 4 MB). The logic board has a RAM-size jumper/resistor that must be set to match the fitted SIMMs — a mismatch after a RAM change is a common cause of a wrong chime or RAM errors.

== Programmer's switch ==

The reset and interrupt (programmer's) switch clips onto the left side. A jammed or shorted switch can hold the machine in reset (dead or looping); confirm the switch is free and not shorting before deeper diagnosis.

== References ==

== Related Pages ==

@@ Line 109: / Line 109: @@
 | 10–100µF electrolytics || Random resets, noise, video flicker || Replace with modern electrolytics of equal or higher voltage.
 |}
+== ⚠️ RIFA mains filter capacitor (smoke) ==
+The Macintosh Plus power supply contains a '''RIFA''' paper/film mains-suppression capacitor that cracks with age and fails by emitting acrid smoke shortly after power-on. This is one of the most common Plus faults. Replace the RIFA X2 capacitor pre-emptively with a modern X2-class part (a few-minute through-hole job); do '''not''' keep running the machine once it has smoked.<ref name="plus_rifa">[https://www.crackedthecode.co/replacing-failed-capacitors-in-a-macintosh-computer/ "Vintage Computer Up In Smoke"], Cracked the Code; and [https://recapamac.com.au/macintosh-plus/ Macintosh Plus], Recap-a-Mac. Source for the RIFA mains-filter failure, the leaking alkaline PRAM battery, the cracked analog-board solder joints and the recap.</ref>
+== ⚠️ PRAM battery leakage ==
+The Plus uses an alkaline PRAM battery behind a door on the rear of the case. These leak badly, and the electrolyte runs down onto the analog board and corrodes it. Remove the battery on any un-serviced Plus and clean/repair any corrosion.<ref name="plus_rifa" />
+== No video from cracked analog joints ==
+The Plus commonly develops cracked solder joints on the larger analog-board components and connectors from heat cycling, giving a "no video" fault with the machine otherwise alive. Reflow the analog-board solder joints, especially around the deflection-yoke and flyback area and the analog-to-logic harness.<ref name="plus_rifa" />
+== SCSI and RAM ==
+The Plus was the first Macintosh with built-in SCSI (NCR 53C80). Period SCSI drives are commonly dead; fit a '''BlueSCSI''' or '''SCSI2SD''', and note that some SCSI adapters need termination power (TERMPWR) added at the connector on the Plus.<ref name="plus_rifa" /> RAM is four 30-pin SIMMs (256&nbsp;KB or 1&nbsp;MB SIMMs giving 512&nbsp;KB, 1&nbsp;MB, 2&nbsp;MB or 4&nbsp;MB). The logic board has a RAM-size jumper/resistor that must be set to match the fitted SIMMs &mdash; a mismatch after a RAM change is a common cause of a wrong chime or RAM errors.
+== Programmer's switch ==
+The reset and interrupt (programmer's) switch clips onto the left side. A jammed or shorted switch can hold the machine in reset (dead or looping); confirm the switch is free and not shorting before deeper diagnosis.
+== References ==
+<references />
 == Related Pages ==