PowerBook Duo General Maintenance

Apple's exploded view of the PowerBook Duo 200 Series (Service Source, PDF p. 266)

The PowerBook Duo 210, 230, 250, 270c, 280, 280c and 2300c share one case design, so Apple's care and disassembly procedures are almost the same for all of them. The procedures below come from the two Service Sources, the PowerBook 200 Series manual for the 68k models and the PowerBook 2300 Series manual for the 2300c; differences are marked. Electrolytic capacitors are covered on PowerBook Duo Capacitor Replacement Guide and its faults on PowerBook Duo Troubleshooting.

Identify the machine

Duo models and their parts

Model	Processor	Display	Service logic board	Main battery	Adapter output
210	68030, 25 MHz	9-inch FSTN greyscale	661-1653	Type 1, 0.95 Ah	24 V, 1.04 A
230	68030, 33 MHz	9-inch FSTN greyscale	661-1653, 661-1672	Type 1, 0.95 Ah	24 V, 1.04 A
250	68030, 33 MHz	9-inch active-matrix greyscale	661-1653, 661-1672	Type 2, 1.5 Ah	24 V, 1.04 A
270c	68030, 33 MHz, 68882	9-inch active-matrix colour	661-1653, 661-1717	Type 2, 1.5 Ah	24 V, 1.04 A
280	68LC040, 66/33 MHz	9-inch active-matrix greyscale	661-0051	Type 3, 1.6 Ah	24 V, 1.04 A
280c	68LC040, 66/33 MHz	8.4-inch active-matrix colour	661-0051	Type 3, 1.6 Ah	24 V, 1.5 A
2300c	PowerPC 603e, 100 MHz	9.5-inch active-matrix colour	661-0153	Type 3	24 V, 1.5 A, 36 W

Apple sold upgrade kits that moved a Duo up to a 250, 270c, 280, 280c or 2300c, so the bezel label does not prove what is inside. Apple identifies a 250 by its display cable. The 280c and 2300c adapter figures come from Apple's specification pages, which give 36 W for both.

Tools

Apple lists T-8 and T-10 Torx drivers, an IC extractor for lifting the flat-cable connectors, a jeweller's flat-blade screwdriver and the Duo battery contact alignment tool. The 2300c also needs a T-6 Torx and a No. 00 Phillips driver. Early hard drive brackets use Phillips screws. See also Recommended Tools.

Safety and handling

• Disconnect the adapter and take out the main battery before any take-apart step. Apple warns that skipping this can short the logic board.
• The boards are CMOS and easily damaged by static; wear an earthed wrist strap.
• The flat cables tear easily, the display cable under the centre clutch cover most of all.
• On a 250 or 280, do not touch the copper coating inside the display housing; it flakes and the flakes can short the machine. Leave the protective tape on the 250/280 inverter board in place.

Disassembly order

Apple's sequence for reaching the logic board of a 200 Series Duo:

1. Slide open the battery door with its release button and pull out the main battery.
2. Close and latch the computer, turn it over, and remove the four case screws in the base. To remove only the keyboard, the front screw can stay in.
3. Turn the computer upright, open it, tilt it and lift the keyboard out onto the palm rest. Push out the release tabs with a jeweller's screwdriver and unplug the two keyboard cables.
4. Push off the left and right end clutch covers. Apple treats them as disposable.
5. Raise the bottom left corner of the top case to release its snap, then slide the case off the four interlocking tabs along the front. Lifting the case without unlocking those tabs damages it.
6. Remove the three self-threading screws holding the hard drive to the CPU stiffener, unplug its cable with the IC extractor, fold back the EMI shield and lift the drive out.
7. Lift the backup battery out of the trackball assembly and unplug its cable.
8. Remove the two screws holding the trackball assembly and unplug its cable.
9. Unplug the display switch cable and the display cable, lift the microphone off the CPU stiffener, and remove the three stiffener screws. Lift the stiffener and display out together.
10. Remove the last logic board screw, raise the side of the board away from the 152-pin docking connector, and slide the connector out of the case. Unplug the microphone cable, the on/off board or modem, and the RAM card.

Remove the centre clutch cover only when replacing the CPU stiffener, the display assembly or the rear cover. The display cable runs beneath it and is easily torn. The 2300c follows the same order, with a trackpad instead of a trackball; its trackpad carrier is held by four T-8 screws, and the trackpad cable has to be eased through the trackpad button.

Reassembly

• The leftmost CPU stiffener screw and one logic board screw are also the battery contacts. If either is left out, the battery may not charge.
• Check that both EMI clips are secure on the CPU stiffener; Apple replaces a stiffener with a loose clip.
• Wrap the hard drive EMI shield around the outside of the stiffener, and tuck the drive cable underneath it.
• Route the display switch cable and the backup battery cable around the trackball, and move the display switch and microphone cables forward so the stiffener does not trap them.
• A replacement stiffener needs a foam heatsink pad under its tab: small on the 210, 230, 250 and 270c, large on the 280 and 280c.
• Fit the foam gaskets to a new case bottom only on a 270c. On the other models they can short components on the board.
• Do not overtighten the keyboard screws. They warp the keyboard and stop the space bar moving; check every key afterwards.
• The Duo will not run unless the on/off board or a modem is plugged into the logic board.
• Check the battery contact alignment, below.

Battery contacts

Apple aligns the battery contacts whenever a logic board is replaced, a battery contact screw has been loosened, or a known-good battery will not charge or the machine shuts down on battery. The procedure:

1. Remove the main battery, keyboard, end clutch covers and top case.
2. Slide the Duo battery contact alignment tool into the battery bay. If contacts 1 and 5 (the outer two) flex or resist the tool, they are out of line.
3. Remove the tool, loosen the two battery contact screws and the two CPU stiffener screws.
4. Push the tool back in against the contacts and tighten all four screws.

The centre contacts, 2 to 4, are soldered to the board and aligned at the factory. Apple's answer to a bent centre contact was a new logic board.

Main battery

All Duo main batteries are NiMH. Apple's Type 1 pack shipped with the 210 and 230, Type 2 with the 250 and 270c, and Type 3 with the 280, 280c and 2300c. Apple's notes on the types:

• Type 2 and Type 3 packs say "High-Capacity Type 2" or "High-Capacity Type 3" on the underside; Type 1 packs have no such label.
• An older Duo needs Apple's Type 2 or Type 3 battery software installed before it can use the newer packs.
• A Type 1 recharger, marked "Macintosh PowerBook Duo Battery Recharger", charges Type 1 packs only. A Type 2 recharger, marked "PowerBook Duo Battery Recharger", charges all three, but has to be connected once to a Duo with the Type III battery extension before it will charge a Type 3 pack. The recharger LED is yellow while charging, green when charged, and red when the pack is a type that recharger cannot charge.

Apple's handling instructions were to charge a new pack fully before use, not to leave a pack in the computer for more than a week without recharging, to discharge and recharge it once every 30 days, and to store it cool and dark for no more than six months between charges.

To check a pack, measure across its positive and negative terminals on the 20 V DC range. Apple's charged figure is 12 V; recharge a pack that reads less, and replace one that stays below 6 V.

Owners rebuild old packs with 4/5 A NiMH cells, ten to a pack according to Powerbook27364, and Sideburn rebuilt one with AA cells. Keep the pack's Dallas DS2400 identification chip: Sideburn's 2300c would not run from the battery terminals without it. The Apple 200 Series manual puts the 250 and 270c pack at 4/5 A size cells too. See Battery Refurbishment.

Backup battery

The 200 Series Duos have a 3 V lithium PRAM battery that sits in the trackball assembly on a lead to the logic board, which keeps it away from the board itself. The 2300c has a rechargeable lithium cell, part 922-1418. On the 2300c, every time the backup battery is unplugged the power manager has to be reset before the machine will power up. If old cells have leaked, see Battery Explosion, Capacitor or Corrosion Damage.

Power manager reset

Hold the rear power switch for 30 to 45 seconds. If that does not help, remove the main battery, the adapter and the backup battery and leave the machine for ten minutes; it then reloads the power manager code from the system software.

Adapter check

Plug the adapter in and connect it to the Duo. With the meter's negative probe on the plug contact nearest the cable and the positive probe on the next contact, Apple expects 24 to 25 V DC. Repeat with the computer switched on; a drop of more than 1 to 2 V means a new adapter. MacDat notes that some Duo adapters contain a RIFA filter capacitor that cracks and smokes with age. Inside, the adapter runs at mains voltage, and its 100 µF 400 V primary capacitor can hold a charge after it is unplugged.

Keyboard, trackball and trackpad

• Trackball: clean the ball and rollers when the cursor sticks or jumps. jmacz cleaned a gummed trackball with isopropyl alcohol on a swab. Early trackball boards carry one 10 µF electrolytic that leaks; see the capacitor guide.
• Keyboard: the Duo keyboard comes apart once the keycaps are pulled, which releases the layers. chartreuse restored dead keys by rubbing the membrane contacts with a white eraser after contact cleaner had failed; jmacz cleaned the contacts with DeoxIT and relubricated the key stems, which improved but did not cure every key.
• Trackpad (2300c): when refitting, put the lower left carrier screw in its proper hole, thread the cable through the centre of the carrier, and fit the button before the carrier.

Display housing

The plastic bosses that hold the brass inserts for the two bezel screws break away. The symptom is a bezel screw that turns without coming out. Fizzbinn set the inserts back in JB Weld PlasticWeld epoxy; jmacz printed new stand-offs and epoxied them in, and also repaired a broken speaker mount. Apple's own cautions for the housing are to remove it slowly so the display layers do not shift, to engage its four front tabs carefully on refitting, and not to overtighten the T-6 bezel screws, which strip their inserts.

Hard drive

The 200 Series takes a 2.5-inch SCSI drive 17 mm high. The 2300c has connectors for both SCSI and IDE drives, but its cables are not interchangeable and Apple fits like for like; IDE drives have extra pins at one side that the cable does not use, and fitting the cable upside down bends pins. On a 2300c, refit the display actuator to the CPU stiffener before the drive, or the machine will not sleep when the lid closes. SCSI emulators such as the ZuluSCSI fit the 200 Series but need a new mount, because the drive is fixed from the side. See Hard Drive Maintenance and Repair.

Preventive checklist

1. Take the main battery out of a Duo that is going into storage. Apple's instruction is not to leave a pack in the computer for more than a week without recharging.
2. Check the adapter at 24 to 25 V, unloaded and loaded.
3. Inspect the logic board electrolytics and the display for leakage, and plan a recap; see PowerBook Duo Capacitor Replacement Guide.
4. Clean the trackball rollers or the trackpad surface.
5. Check that the battery contacts are straight with the alignment tool.
6. Check the display bezel screws and hinge area for broken bosses before forcing anything.

Related pages

• PowerBook Duo Troubleshooting
• PowerBook Duo Capacitor Replacement Guide
• PowerBook Duo 200 Series Service Source, PowerBook Duo 2300c Service Source
• Capacitor Failure Symptoms