Editing PowerBook 100 Troubleshooting

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[[File:PowerBook 100 (Danamania).jpg|thumb|300px|PowerBook 100 (Danamania, Wikimedia Commons, CC0)]]
Fault-finding on the [[PowerBook 100]] starts from Apple's symptom charts, which work at module level. Apple's rule is to try the cures in the order listed, test after each, and refit the original module before trying the next.<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: General p. 13; Power Manager Reset p. 14; Symptom Charts: Startup p. 15, Power pp. 16-18, Video pp. 19-24, Hard Drive pp. 25-26, Peripheral pp. 27-31, Internal Modem pp. 32-35, Miscellaneous p. 36; Backup Batteries pp. 39-41; Fuse pp. 97-100; SCSI Termination pp. 103-104; Battery Verification pp. 108-109; AC Adapter Verification pp. 110-111.</ref> Most PowerBook 100s found today also need a full recap before the charts mean much; see [[PowerBook 100 Capacitor Replacement Guide]].<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. Secondary source.</ref>

== Before you start ==
* Check that the storage switch on the back is in the "on" position. It disconnects all power, and Apple lists it as the first cure for a dead machine.<ref name="ss" />
* Check the adapter: 7.5-7.9 V between the inside (positive) and the outside of the plug on a meter's 10 V DC range.<ref name="ss" />
* Check the main battery with a meter. Below 5.7 V, recharge or replace it.<ref name="ss" /> See [[PowerBook 100 Battery Replacement]].
* Reset the power manager when the battery and adapter are good and the machine will not power on or will not restart after a crash: remove the adapter and the battery, wait 3-5 minutes, then hold Control, Command, Option and the power key together for 5-10 seconds. Refit the battery, reconnect the adapter and switch on.<ref name="ss" />

== Power ==
{| class="wikitable styled-table" style="width:100%;"
! Symptom !! Probable cause !! Action
|-
| Blank screen, no response || Storage switch off; battery flat; power manager; keyboard cable; boards || Apple's order: check the storage switch; reset the computer; connect the adapter and restart after 3-4 minutes; try a known-good charged battery; check the keyboard cable; reset the power manager; replace the keyboard, daughterboard, motherboard<ref name="ss" />
|-
| Dead on battery and adapter; fuse open || Blown motherboard fuse || The fuse sits in holders under the keyboard on boards that have a removable one. Where the fuse is soldered in, Apple's remedy is a new motherboard<ref name="ss" /> MacDat's board photograph shows the fuse as F1, marked 5A<ref name="md" />
|-
| Control Panel settings change after the main battery is changed || Backup batteries flat || Replace the three backup batteries<ref name="ss" />
|-
| Settings change after all power is removed || Normal || Removing every power source clears settings held in parameter RAM, such as the time<ref name="ss" />
|-
| Adapter connected but the battery desk accessory does not show the charger || Adapter connection, battery, adapter, motherboard || Check the adapter connection; try another battery; test and replace the adapter; replace the motherboard<ref name="ss" />
|-
| Low-power warning soon after starting || Battery needs charging; heavy drain || Connect the adapter; reduce use of the drives, modem, sound and backlight<ref name="ss" />
|}

== Startup ==
{| class="wikitable styled-table" style="width:100%;"
! Symptom !! Probable cause !! Action
|-
| Error chord at startup || Flat battery; RAM card; motherboard; daughterboard || Connect the adapter and restart after 3-4 minutes; replace the memory expansion card; replace the motherboard, then the daughterboard<ref name="ss" />
|-
| Checkerboard, no startup chime || RAM card; daughterboard; display cable || Reseat and replace the RAM card; replace the daughterboard; reseat the display cable<ref name="ss" />
|-
| Sad Mac 0000000E / 0000FF00 || Daughterboard capacitor or connector || Pilgrim33 got this code after washing a PB100's boards; swapping in another CPU card cleared it, and so did replacing the single capacitor on the original CPU card. Byrd points out that the daughterboard connector is fragile and reseating it can also clear the error<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: sad Mac 0000000E 0000FF00 after washing the boards, cured by replacing the CPU card capacitor; afterwards no SCSI devices were seen. Byrd: the CPU card capacitor can leak and the daughter card connector is fragile. Community repair report.</ref>
|-
| Flashing question mark; no internal or external SCSI device seen || SCSI path; Combo chip corrosion || imactheknife cured one by reflowing the AM85C80 Combo chip, which handles SCSI and serial, after cleaning corrosion from its legs<ref name="scsi">68kMLA forum thread [https://68kmla.org/bb/threads/powerbook-100-scsi-chip.51999/ "Powerbook 100 scsi chip"], April 2026. Fizzbinn: the Combo chip (AM85C80) combines SCC and SCSI; imactheknife: corroded legs, reflowed with hot air, fixed; finkmac: probably residue shorting pins. Community repair report.</ref>
|}

== Video ==
Apple counts a slight white line across the middle of the screen, rainbow colours at extreme angles, an uneven image, and a screen that stops working or dims below 5 °C, above 45 °C or in extreme light and then recovers as normal for the PowerBook 100's display.<ref name="ss" />

{| class="wikitable styled-table" style="width:100%;"
! Symptom !! Probable cause !! Action
|-
| Backlight on, chime and keyboard sounds, screen blank || No LCD drive voltage (LCD_VEE) || The panel needs about −22 V on LCD_VEE, measured at test point TP055. alexGS starts with C22, in the corner of the logic board and involved in producing this voltage (47 µF 35 V on Console5's list),<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 capacitor list including C22 47 µF 35 V. Secondary source.</ref> and the eight 3.3 µF capacitors on the LCD; finkmac's next steps are cleaning under inductors L2, L3 and L4 and the FA7611 controller (U25), then replacing the FA7611<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. asentientbot: 4.7 V and later 0.16 V at TP055 against an expected −22 V after a recap; L2, L3, L4, U25 cleaned and FA7611 replaced without change; finkmac: the LCD will not turn on without the ~−22 V twist voltage; alexGS: replace C22 first, then the eight 3.3 µF LCD capacitors; polariser film replacement on these panels gives poor contrast. Community repair reports.</ref>
|-
| Very light, white or no picture with the machine running || Contrast; cable; inverter; interconnect board; display; boards || Adjust contrast and brightness; check the interconnect cable at the motherboard; replace the inverter board, interconnect cable, interconnect board, display, daughterboard, motherboard<ref name="ss" />
|-
| Backlight does not light || Brightness setting; inverter; cables; boards || Adjust brightness; check the interconnect cable; replace the inverter board, interconnect cable, interconnect board, display, daughterboard, motherboard<ref name="ss" />
|-
| Row of pixels never on or always on || Interconnect cable; display; boards || Replace the interconnect cable, display, interconnect board, daughterboard, motherboard<ref name="ss" />
|-
| Band of rows at the bottom of the screen dead after a recap || Row driver or ribbon cable corroded by leaked electrolyte || 3lectr1cPPC reports this is now common and not practically repairable; look for black spots of corrosion on the bottom ribbon<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 traces inside the ribbon; very common; no practical fix. Community experience.</ref>
|-
| Half the screen a solid colour, the rest normal || Missing bias to one set of row drivers || GRudolf94's advice: check continuity and compare the voltages on the pins of the upper and lower row drivers<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. GRudolf94: most likely a missing bias voltage to the lower row drivers; vetz measured about −21 V on the −22 V line. Community repair report, unresolved.</ref>
|-
| Blotches or a mottled picture after cleaning || Liquid between the diffuser film and the acrylic light guide || finkmac: these parts are sensitive to oils and solvents; clean or replace them, or move the backlight parts over from a panel with a broken LCD<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 and 3lectr1cPPC: contamination of the diffuser and light guide; Byrd: pink bloom where the trackball rests under the LCD. Community repair report.</ref>
|-
| Screen goes blank || Sleep || Normal: the machine has gone to sleep to save power; adjust the sleep delays or connect the adapter<ref name="ss" />
|}

== Hard disk and peripherals ==
{| class="wikitable styled-table" style="width:100%;"
! Symptom !! Probable cause !! Action
|-
| Internal hard disk does not work || External devices off; flex cable; driver; drive; boards || Switch on all external SCSI devices; check the hard drive flex cable at both ends; check the drive in HD SC Setup and update the driver; reinstall system software; replace the flex cable, drive, motherboard, daughterboard<ref name="ss" />
|-
| No boot with an external SCSI device || Power-up order; cable; termination; IDs || Switch the device on first; check the HDI-30 cable; terminate the chain correctly with standard Apple terminators (the PowerBook 100 has none on the board); make IDs unique<ref name="ss" />
|-
| Cursor does not move with the trackball || Reset; connection; trackball; boards || Reset; check the trackball to motherboard connection; replace the trackball assembly, daughterboard, motherboard<ref name="ss" />
|-
| Cursor moves erratically || Dirty ball and rollers || Clean the ball and rollers; replace the trackball assembly<ref name="ss" />
|-
| No response from the keyboard || Reset; flat battery; keyboard cable; keyboard; boards || Reset; connect the adapter and restart after 3-4 minutes; try a charged battery; check the keyboard cable; replace the keyboard, daughterboard, motherboard<ref name="ss" />
|-
| No sound from the speaker || Volume setting; speaker connection; motherboard || Set the volume to 1 or above; check the speaker connection; replace the motherboard<ref name="ss" />
|-
| Applications slow down after a few seconds || System rest || Normal power saving; connect the adapter if it interferes<ref name="ss" />
|}

== Related pages ==
* [[PowerBook 100]]
* [[PowerBook 100 General Maintenance]]
* [[PowerBook 100 Capacitor Replacement Guide]]
* [[PowerBook 100 Battery Replacement]]
* [[PowerBook 140 Troubleshooting#Power adapter]]
* [[Hard Drive Maintenance and Repair]]

== References ==
<references />

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