Editing PowerBook 100 Capacitor Replacement Guide

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[[File:PowerBook 100 logic board capacitor map (MacDat).jpg|thumb|420px|The PowerBook 100 logic board (PU-58) with its electrolytic capacitors circled by value (MacDat)]]
Unlike the [[PowerBook 140]], the [[PowerBook 100]] has electrolytic capacitors on its logic board as well as on the LCD, the inverter and the trackball, and they leak. MacDat's advice is that every PowerBook 100 must be fully recapped.<ref name="md">MacDat, [https://macdat.net/repair/cap_reference/apple/powerbook/100.php "Capacitor Reference - PowerBook 100"] (retrieved 2026-10-02). Any PowerBook 100 must be fully recapped; the logic board varnish becomes sticky with isopropyl alcohol; logic board 330 µF 16 V ×1, 220 µF 25 V ×1, 100 µF 10 V ×3, 47 µF 35 V ×1 (radial electrolytic), 47 µF 16 V ×5, 10 µF 16 V ×5, 4.7 µF 50 V ×1, 1 µF 50 V ×5 (surface-mount electrolytic); CPU daughtercard 10 µF 16 V ×1; Sharp LM64P791 LCD 3.3 µF 35 V ×8 (low-profile surface mount; tantalums preferred to ceramics); inverter 47 µF 16 V radial electrolytic and 15 µF 16 V radial polymer; trackball 10 µF 16 V and 0.22 µF 50 V radial electrolytic. Secondary source.</ref> Leaking capacitors and the residue they leave cause blank or partial pictures, a missing LCD drive voltage and boards that will not start. Apple's Service Source gives no capacitor values; the lists below are from Console5 and MacDat, which publish them independently.<ref name="c5">Console5 TechWiki, [https://wiki.console5.com/wiki/Macintosh_PowerBook_100 "Macintosh PowerBook 100"] (retrieved 2026-10-02). Main PCB 1-640-290-12: aluminium electrolytics C11, C12, C13, C20, C22, C23, C25, C26, C30, C32, C37, C38, C42, C43, C102, C104; "OEM polymer caps, reference only, replacement generally not required": C6, C21, C24, C27, C34 (47 µF 16 V) and C39 (4.7 µF 50 V); CPU/memory daughterboard IF-54 1-640-491-12: C310; inverter 1-466-589-11: C1 15 µF 16 V, C4 47 µF 16 V, listed as polymer; Sharp LCD board C1-C8 3.3 µF 35 V; Logitech Derringer trackball 220260-00: C1 0.22 µF 50 V, C2 10 µF 16 V. Secondary source.</ref><ref name="ss">Apple Computer, ''PowerBook 100'' Service Source, hosted here as [[:File:PowerBook 100 Service Source.pdf]] (see [[PowerBook 100 Service Source]]). PDF page numbers: Guidelines p. 38; Backup Batteries pp. 39-41; Main Battery pp. 44-45; Display Assembly pp. 50-53; Keyboard pp. 54-56; Palm Rest Cover pp. 57-59; Trackball Assembly pp. 60-61; Hard Drive pp. 62-65; Daughterboard pp. 70-71; Motherboard pp. 72-73; Top Cover pp. 74-77; Display Bezel pp. 78-80; Display pp. 81-85. Module-level only; no component values.</ref>

== Capacitor list ==

=== Logic board (PU-58) ===
{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+ '''PU-58 logic board electrolytic capacitors'''
! Ref !! Capacitance !! Voltage !! Type (MacDat) !! Console5
|-
| C6 || 47 µF || 16 V || Surface mount || Listed as polymer
|-
| C11 || 1 µF || 50 V || Surface mount ||
|-
| C12 || 1 µF || 50 V || Surface mount ||
|-
| C13 || 10 µF || 16 V || Surface mount ||
|-
| C20 || 10 µF || 16 V || Surface mount ||
|-
| C21 || 47 µF || 16 V || Surface mount || Listed as polymer
|-
| C22 || 47 µF || 35 V || Radial ||
|-
| C23 || 330 µF || 16 V || Radial ||
|-
| C24 || 47 µF || 16 V || Surface mount || Listed as polymer
|-
| C25 || 1 µF || 50 V || Surface mount ||
|-
| C26 || 1 µF || 50 V || Surface mount ||
|-
| C27 || 47 µF || 16 V || Surface mount || Listed as polymer
|-
| C30 || 100 µF || 10 V || Radial ||
|-
| C32 || 220 µF || 25 V || Radial ||
|-
| C34 || 47 µF || 16 V || Surface mount || Listed as polymer
|-
| C37 || 100 µF || 10 V || Radial ||
|-
| C38 || 100 µF || 10 V || Radial ||
|-
| C39 || 4.7 µF || 50 V || Surface mount || Listed as polymer
|-
| C42 || 10 µF || 16 V || Surface mount ||
|-
| C43 || 1 µF || 50 V || Surface mount ||
|-
| C102 || 10 µF || 16 V || Surface mount ||
|-
| C104 || 10 µF || 16 V || Surface mount ||
|}
Designators and values are Console5's; the type column is MacDat's, matched by value. The two lists agree on the count of every value: 22 capacitors in all.<ref name="c5" /><ref name="md" />

Console5 marks six of these as factory polymer parts that need not be replaced, and leaves them out of its kit. Owners dispute this. 3lectr1cPPC states that the 47 µF 16 V parts are electrolytics that leak, and suspects only C39 may be polymer; imactheknife has found all of them to be electrolytic and leaking on several boards; MacDat lists all six as surface-mount electrolytics.<ref name="poly">68kMLA forum thread [https://68kmla.org/bb/threads/powerbook-100-factory-polymer-caps.50817/ "Powerbook 100 - factory polymer caps?"], September 2025. JC8080: Console5's kit omits six caps it calls polymer; Pilgrim33 and ObeyDaleks replaced all of them, ObeyDaleks seeing corrosion under the parts in question; 3lectr1cPPC: the 47 µF 16 V parts are electrolytic and leak, only one inverter capacitor is polymer, the 4.7 µF 50 V part may be polymer; finkmac: trust MacDat over Console5; imactheknife: all electrolytic, all leak. Community experience.</ref> Replace all 22.

C22 is part of the circuit that makes the LCD drive voltage; alexGS replaces it first on boards with a blank screen.<ref name="vee">68kMLA forum thread [https://68kmla.org/bb/threads/powerbook-100-display-lcd_vee-issue-but-inductors-ok.49563/ "PowerBook 100 display, LCD_VEE issue but inductors ok?"], March-May 2025. alexGS: replace C22 first, then the eight 3.3 µF LCD capacitors; finkmac: about −22 V is needed at LCD_VEE (test point TP055). Community repair reports.</ref>

=== CPU daughterboard (IF-54) ===
One capacitor, C310, 10 µF 16 V, surface mount.<ref name="c5" /><ref name="md" /> Pilgrim33 cleared a sad Mac (0000000E 0000FF00) by replacing it.<ref name="sad">68kMLA forum thread [https://68kmla.org/bb/threads/powerbook-100-sad-mac-bus-failure-conundrum.50000/ "PowerBook 100 sad Mac bus failure conundrum"], May 2025. Pilgrim33: replacing the single CPU card capacitor cleared sad Mac 0000000E 0000FF00. Community repair report.</ref>

=== LCD (Sharp LM64P791) ===
[[File:PowerBook 100 Sharp LM64P791 LCD capacitor map (MacDat).jpg|thumb|350px|The eight 3.3 µF capacitors on the PowerBook 100's LCD board (MacDat)]]
Eight 3.3 µF 35 V low-profile surface-mount electrolytics, C1-C8.<ref name="c5" /><ref name="md" /> MacDat prefers tantalums to ceramics here, because ceramics lose capacitance under DC bias and have caused contrast drift.<ref name="md" /> 3lectr1cPPC has used tantalums in a PB100 without trouble; GRudolf94 questions whether tantalums are the best choice.<ref name="half">68kMLA forum thread [https://68kmla.org/bb/threads/only-half-of-screen-showing-on-powerbook-100-red-solid-color-on-rest.51183/ "Only half of screen showing on PowerBook 100 (red solid color on rest)"], December 2025. vetz: 3.3 µF 35 V tantalums on the panel; GRudolf94: tantalums might not be the best choice; 3lectr1cPPC: used tantalums on his PB100 with no ill effects so far. Community experience.</ref>

=== Inverter board ===
[[File:PowerBook 100 inverter board capacitor map (MacDat).jpg|thumb|350px|The PowerBook 100 inverter board with its two capacitors (MacDat)]]
{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+ '''Inverter board (1-466-589-11)'''
! Ref !! Value !! MacDat !! Console5
|-
| C1 || 15 µF 16 V || Radial polymer || Polymer
|-
| C4 || 47 µF 16 V || Radial electrolytic || Polymer
|}
3lectr1cPPC agrees with MacDat that only one of the two is a polymer part.<ref name="md" /><ref name="c5" /><ref name="poly" /> Replace C4.

=== Trackball (Logitech Derringer 220260-00) ===
C1 0.22 µF 50 V and C2 10 µF 16 V, both radial electrolytics.<ref name="c5" /><ref name="md" />

== Procedure ==
Apple's take-apart order, from the Service Source. Shut down with the Shut Down command first; removing power without shutting down loses the contents of RAM.<ref name="ss" />

=== Remove the logic board ===
# Remove the three backup batteries from behind the backup battery door, then slide the main battery cover to the right and remove the main battery.<ref name="ss" />
# Close the computer so it latches. Move the power (storage) switch to "off" with a screwdriver or pen tip. Apple's caution: do not go on while any battery or the adapter is still connected.<ref name="ss" />
# Turn the computer over, pry off the three rubber covers and remove the three case screws. Turn it the right way up with the elevation feet down, open the display while holding it firmly, disconnect the interconnect cable from the motherboard and lift the display assembly off.<ref name="ss" />
# Lift the back of the keyboard as far as its cables allow, slide it to the rear until the front edge clears the palm rest, unlock the connectors and remove the two keyboard cables.<ref name="ss" />
# Lift the palm rest cover off by its two back corners. Pull the trackball cable out of J5 and remove the trackball.<ref name="ss" />
# Fold back the hard drive shield, unlock and disconnect the flex cable, release the two latches on the side nearest the motherboard and lift the drive out.<ref name="ss" />
# Remove the memory card and the modem shield and modem if fitted. Lift the daughterboard off by its connectors J318 and J319, rocking J318 gently from end to end.<ref name="ss" />
# Remove the five motherboard screws and lift the board out, starting near the hard drive connector.<ref name="ss" />

=== Replace the capacitors ===
# Remove each capacitor and clean every trace of electrolyte from the pads and the surrounding board. MacDat warns that the PowerBook 100 logic board's varnish turns sticky with isopropyl alcohol; either remove it all with plenty of alcohol or clean the leakage another way.<ref name="md" />
# Check the traces and vias near each capacitor for corrosion before fitting the new part.
# Fit the new capacitors to the polarity marked on the board.

=== Reach the LCD and inverter ===
# With the display assembly off, remove the four top cover screws, lift off the two clutch plates and slide off the clutch covers. Release the speaker and the interconnect cable cover and remove the top cover. The speaker is soldered to the interconnect cable.<ref name="ss" />
# Pry the brightness and contrast knobs off their shafts. Pry out the two rubber plugs, remove the two bezel screws, pry the bezel from the metal clutch assembly on each side and lift it off.<ref name="ss" />
# Remove the display shield screw and shield, the inverter board screw, the interconnect board screw and the four display screws. Rotate the display forward onto its face, taking care of the boards and cables that come with it, then disconnect the brightness/contrast flex cable, the display flex cable and the lamp cable.<ref name="ss" />
# On reassembly, press the lamp cable wires back into their channels in the housing and fit the brightness/contrast cable with its blue insulator end towards the interconnect board.<ref name="ss" />

Keep solvents away from the backlight's diffuser film and acrylic light guide; owners have stained them with liquid while cleaning the LCD board.<ref name="blob">68kMLA forum thread [https://68kmla.org/bb/threads/powerbook-100-recapped-lcd-and-logic-board-but-screen-is-blobby.50914/ "Powerbook 100 - Recapped LCD and Logic board but screen is 'blobby'"], October 2025. finkmac: the diffuser film and acrylic light guide are sensitive to oils and solvents; 3lectr1cPPC: a stained light guide on a PowerBook 540 could not be cleaned. Community repair report.</ref>

== After the recap ==
With the adapter connected, the PowerBook 100 should chime and show a picture. If the backlight lights and the machine responds but the screen stays blank, measure LCD_VEE at TP055; it should be about −22 V.<ref name="vee" /> A band of dead rows at the bottom of the screen after a recap usually means the leakage has already corroded the row driver connections, which owners have not been able to repair.<ref name="blue">68kMLA forum thread [https://68kmla.org/bb/threads/powerbook-100-1-8-of-screen-is-still-blue-after-recapping.49834/ "Powerbook 100 1/8 of screen is still blue after recapping"], May 2025. 3lectr1cPPC: failed row driver or corroded ribbon traces; very common; no practical fix. Community experience.</ref> Further fault-finding is on [[PowerBook 100 Troubleshooting]].

The original power adapters have their own leaking capacitors; see [[PowerBook 140 Troubleshooting#Power adapter]].

== Related pages ==
* [[PowerBook 100]]
* [[PowerBook 100 General Maintenance]]
* [[PowerBook 100 Troubleshooting]]
* [[PowerBook 100 Battery Replacement]]
* [[Capacitor Failure Symptoms]]

== References ==
<references />

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[[Category:Apple Vintage Computers]]
[[Category:Capacitor Replacement Guides]]