Replacing the Capacitors on a Macintosh Portable, Model M5120.

Notes

These instructions have not been tested with the first model of Macintosh Portable, Model M5126. There were some changes to the motherboard in the later model so these instructions may or may not apply.

The capacitor designations used are marked on the circuit board. They are assumed to be the same on every board but this has not been verified.

Diagnosis

Note that only one machine was used in making this diagnosis and symptoms may vary from machine to machine. Aging capacitors is likely a problem in many nonfunctional Macintosh Portable computers. The best way to diagnose bad capacitors is to remove some of each type used in the system and test them.

Skills Required

Tools & supplies

Required

Strongly recommended

Suggested

Bill of Materials

Part Description Footprint Digi-Key Part # Qty
C2, C6, C18, C19 100uf, 25V 0.11" Through 493-1548-ND 4
C3 220uF, 25V 0.15" Through P12383-ND 1
C4, C5, C15, C24 1uF, 50V 0.18" Surface 493-2130-1-ND 4
C8, C16, C20 470uF, 25V 1.1" Through 4217PHCT-ND 3
C9-C11, C17, C22, C25-C28 47uF, 16V 0.256" Surface PCE3340CT-ND 9
C14, C116 10uF, 16V 0.18" Surface 565-2534-1-ND 2

Notes

Procedure

  1. Remove the motherboard from the unit.
  2. Clean the board. Dust it off using a suitable air duster. Use a small brush dipped in isopropyl alcohol to clean the area around the capacitors listed in the BOM. Sometimes a residue will build up around some capacitors. Be sure this is fully removed as it may interfere with soldering and desoldering.
  3. Remove the capacitors listed in the BOM. Use the soldering iron and solder wick to remove the surface mount capacitors. A solder sucker may help with the through hole capacitors but they can also be removed with the iron and wick. If the iron fails to melt all the solder make sure it is making proper contact. A very small bead of solder on the iron may help. If it still fails to melt the solder remove the iron, let the board cool, increase the temperature of the iron, and try again. Do not force the parts off as doing so can tear the contact pad off of the circuit board. Remember that the hot iron can easily damage other parts of the board, especially the plastic connectors.
  4. Clean the capacitor mount points with the brush and isopropyl alcohol. Use the soldering iron & wick to remove any excess solder on the pads. Make sure the pads are lightly tinned.
  5. Install the new components as listed in the Bill of Materials. Treat the connections with flux prior to soldering. Make sure the the positive and negative terminals are properly aligned.
  6. Clean off the leftover flux using the brush and isypropyl alcohol. If possible clean in a large isopropyl bath or sonic cleaner. Make sure that all residual flux is removed. Dry board.
  7. Reassemble computer.