Macintosh Performa 550

The Macintosh Performa 550 (also branded as the Macintosh LC 550 and Macintosh Performa 560 Money Edition) was sold from October 1993 until March 1995. The logic board is essentially the same one used in the Macintosh Color Classic II. Like all Macintoshes of its era, its original surface-mount electrolytic capacitors leak their contents and require replacing for both functionality and to protect critical traces on its circuit board from being eaten by electrolyte.

Known Issues

Maxell Battery "Bombs"

Causes

Apple placed a small lithium battery on the Performa 550/LC 550's Logic Board to power and preserve the contents of the Parameter RAM (PRAM). Apple used a number of different brands of battery for this purpose, one of which is Maxell. Maxell lithium batteries are notorious for rupturing in storage and spewing its highly corrosive contents all over the board. If your Macintosh LC III/Performa 450 is still intact with its original PRAM battery, THE BATTERY MUST BE REMOVED IMMEDIATELY, even if it is not Maxell brand.

Solutions

Macintosh LC IIIs/Performa 450s with exploded PRAM batteries are pretty much irreparable, save for replacing the entire Logic Board.

Original Parts

Revision 820-0368-A Logic Board

Capacitor Specifications and Footprint Information

RefDes	Qty	Capitance (μF)	Voltage (V)	Mount	Size	Type	Brand
C1, C2	2	100	6	SMD		Aluminum Electrolytic	Unbranded
C3, C5, C6, C11, C12, C13	6	47	16	SMD		Aluminum Electrolytic	Unbranded
C9	1	10	16	SMD		Aluminum Electrolytic	Unbranded