PowerBook 3400c (Neale Monks, Wikimedia Commons, CC BY-SA 3.0)
Fault-finding for the PowerBook 3400c. The tables follow Apple's symptom charts in the PowerBook 3400c/PowerBook G3 Service Source: try the cures in order, test after each, and refit the original part before trying the next.[1] Community findings are added under the symptoms they explain.
Remove the battery and unplug the adapter before opening the case.[1]
Check the battery with its indicator button and lights; Apple gives no voltage figure. There is no test for the adapter either: try a known-good one.[1]
A machine without enough power to start makes only the click of the power button.[1]
Hold the reset button for 10-20 seconds; repeat three or four times if needed[1]
Will not power up
Adapter, battery, power supply board, logic board
Try a known-good adapter and charged battery; connect the adapter and restart after 3-4 minutes; replace the power supply board, then the logic board[1]
Screen blank, computer does not respond
Power manager, battery, adapter, cables, keyboard, boards
Reset button as above; restart; remove the adapter and battery and restart after 3-4 minutes; check the adapter cable; try a charged battery and a known-good adapter; reset the power manager; check all logic board cables; replace the keyboard, power supply board, logic board[1]
Shuts down on battery when moved or pressed near the battery
Reset the power manager; reseat the battery; try a known-good battery and adapter; replace the power supply board, then the logic board[1]
Low-power warning
Discharged battery, peripherals, power jack
Recharge; disconnect peripherals; reduce drive, sound and backlight use; try a known-good battery and adapter; check the adapter port is not loose, and replace the logic board if it is; then the power supply board and logic board[1]
Shuts down then powers straight back up when Shut Down is chosen on AC
PRAM, power manager
Reset PRAM; then remove the adapter, battery and backup battery for 15 minutes[1]
Control Panel settings lost after the main battery is removed
Backup battery
Check the keyboard and backup battery cables; replace the backup battery; then the logic board[1]
Small popping noise when the adapter is plugged in
Unconfirmed
One owner heard this on a 3400c and sent it for a recap; the cause was not reported[2]
Remove the RAM card and restart; if it starts, refit and retest; reseat; replace the card, then the logic board[1]
Four-tone error chord after the startup chord
PRAM, floppy, hard drive
Reset PRAM; remove the floppy drive and restart; replace the floppy mechanism; unplug the hard drive cable and restart; replace the drive, then the logic board[1]
Startup fails with a minimal System Folder and System 7.6
Chime, then chirps and siren-like noises; the screen lights only with the hard disk unplugged
Stuck IBM Travelstar hard disk
One drive started after a knock; the noise comes from the drive's voice coil. Replace the drive[3]
Apple's startup flowchart: reset the power manager and press the power button. With no tones and no picture, check the keyboard and display cables, then the keyboard and logic board. With a picture but no tones, check the volume and cables, then the speaker and logic board. With no grey screen, check the display and inverter cables, then the display and backlight cables, inverter, display and logic board. For a flashing question mark, reset PRAM, boot from Disk Tools, reinstall the system or reformat the drive, then the hard drive cable, drive and logic board.[1] Sad Mac and chime codes are decoded on Sad Mac Error Codes.
No picture or no backlight while the computer runs, sometimes intermittent
Display cable worked loose from the logic board
Apple's Hot Issue: replace the brightness and speaker grill (922-2488), which carries a foam gasket to hold the connector down[1]
Row of pixels always on or never on
Cables, loose display connector, display
Check the display and backlight cables; if the display connector is loose, replace the grill; replace the display, then the logic board[1]
Display very light or totally white
Settings, connections, inverter, display
Adjust contrast and brightness; check the display cable, inverter and logic board connections; replace the grill if the connector is loose; replace the inverter board, display, logic board[1]
Backlight does not light
Settings, connector, cables, inverter
Adjust brightness; check the backlight cable; replace the grill if the display connector is loose; check for pinched or cut cables; replace the inverter board, display, logic board[1]
No picture, computer appears to work
Sleep, connections, inverter
If the sleep light blinks while the machine is awake, reset the power manager. Insert a floppy and press Command-E to confirm it runs; adjust brightness; check connections and the grill gasket; connect the adapter; replace the inverter, display, logic board[1]
Change the desktop pattern; replace the display if the line stays[1]
External monitor shows nothing, or rolls and distorts
Cable, monitor, logic board
Check the cable; test the monitor elsewhere; replace the logic board[1]
Sleep light will not come on
Power off, power manager, inverter
Check the machine is asleep, not off; reset the power manager; replace the inverter board[1]
The 3400c display cable wraps round the right display clutch inside the lid, and Apple warns that it can tear if its screw hole is not lined up with the clutch when the display is refitted.[1]
Set the volume above 0; unplug external speakers; check the display cable and inverter connections; replace the display cable, inverter board, speakers, logic board[1]
Floppy drive does not work, disk will not eject, read or write errors
Disk, the floppy's internal cable, drive
Try a known-good disk; hold the trackpad button at startup or use a paper clip to eject; check and replace the floppy's internal cable; replace the drive, then the logic board[1]
Internal hard drive does not spin up
Adapter, SCSI devices, cable, driver, drive
Connect the adapter; disconnect external SCSI devices; check and replace the cable; reinitialise with Hard Drive Format; replace the drive, then the logic board[1]
CD-ROM drive will not take a disc, mount or play
Disc, module seating, drive
Replace the disc; reinsert the CD-ROM module; check its internal cable; replace the drive[1]
PC Card will not eject
Sleep, blocked slot, damaged card
Make sure the machine is not asleep and the slot is clear; use a paper clip in the hole beside the slot; use needle-nose pliers; replace a warped card[1]
PC Card not on the desktop
Card, slot, logic board
Try the other slot; replace the card, then the logic board. Modem and network cards may not appear on the desktop[1]
Machine with a PC Card hangs or slows during floppy access
Shut down, remove the adapter and battery for a minute; reset the power manager; check the trackpad, keyboard and logic board connections; plug in a low-power mouse to tell trackpad from keyboard; then the logic board[1]
Cursor erratic
Technique, dirty pad
Use one finger pointing straight down; clean the pad with the machine off; check its connections; replace the trackpad, keyboard, logic board[1]
No response to any key
Power manager, keyboard cables
Reset the power manager; disconnect and reconnect the keyboard cables; replace the keyboard, then the logic board[1]
Serial device such as a digital camera not recognised
Modem will not reset after disconnecting, errors during z-modem uploads, or drops on large downloads
Modem driver, not heat
Install Apple's PB 3400 Modem Driver Update instead of replacing the modem[1]
Machine will not start after Password Security is enabled with At Ease 4.0
Disk driver corrupted
Low End Mac quotes Apple's warning never to combine Password Security with At Ease 4.0's floppy-startup block; Password Security is also incompatible with Mac OS 8.0 on the 3400[4]
↑TinkerDifferent forum thread "PowerBook 3400 small popping noise when plugged in", RetroTechTom, June 2026. A popping noise on connecting a known-good charger; the Varta PRAM battery removed, without leakage. Community experience.
↑TinkerDifferent forum thread "PowerBook 3400 siren song", Elemenoh, starlite and others, May-June 2024. Community experience.
↑Low End Mac, "PowerBook 3400c" (retrieved 2026-10-02). Apple Knowledge Base article 24014 on Password Security and At Ease 4.0; Password Security incompatible with Mac OS 8.0 on the 2400 and 3400. Secondary source.
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