Resources
Wiki
Teardown (read the comments for missing steps)
Disassembly Guide
Umbilical Cord Pinout
Bose Buzz Fix
Documents
[doc_library doc_category=”tam” status=”publish” search_box=”false”]
Main Unit – Internals
Motherboard
Memory
DIsplay Interface Board
Rear I/O Board
TV Tuner
Video Decoder
Cabling Loom
HD Adapter
CD-ROM
Matsushita CR-504-D
Floppy Drive
Mitsubishi MF355H-498MA
Hard Drive
2GB IBM DCRA-22160
Hard Drive Harness and Fan
Buttons Panel Boards
CD-ROM Door Opening Actuator
Speakers
Pay special attention when mounting speakers, so that the terminals don’t touch the computer cover. The whole interior of the cover is conductive. If they touch it, they will be shorted to the computer ground and the amplifier will shut down and there will be no sound. Check the resistance between the speaker cables and the cover interior or some ground point and make sure they are disconnected.
Display
The original display is Samsung LT121S4-105. It is identical to the display in Powerbook 3400. You may also find and use other compatible models, for example Sharp LQ12S11. Here are the pictures showing my original screen crashed. I successfully replaced it with the one from Powerbook.
A compatible Sharp screen:
Keyboard
Touchpad
Main Unit – Reassembly
Keyboard
Front Part
Back Part
Subwoofer Unit – Internals
The separate Bose subwoofer unit has three functions:
- The subwoofer speaker
- Power Supply Unit – it seems to be a regular PC power supply with fan
- Bose amplifier for the subwoofer and main speakers
The subwoofer is connected to the main unit with so called Umbilical Cord – a detailed description of the pins on all connectors can be found here.
The cord carries all the traditional PSU power lines between the main unit and the PSU. It also transmits audio left and right channels from the main unit to the amplifier and the amplified speaker signals back to the speakers in the main unit.
Subwoofer Speaker
Amplifier
It is a custom Bose amplifier based on TDA7375 power amplifier chip and their own analog signal processing ICs: BOSE 133524. The only source for Bose chips I found was Aliexpress, I ordered them and they worked fine as a replacement. I could not find their specification. When replacing Bose chips, don’t use sockets, solder them directly to the board, as any loose or oxidised connections will visibly impair the analog audio quality.
The connector to the amplifier board has the following signals:
| Pin | Signal | Cable color | Meaning |
|---|---|---|---|
| 1 | Power +12V | Yellow | Power from PSU |
| 2 | Power ground | Black | Power ground from PSU |
| 3 | Gap | ||
| 4 | SPKR RTRN | Gray | Speakers shared ground – isolated from other signals |
| 5 | SPKR LHS (or RHS) | Purple | Speaker output signal left or right (I don’t remember) |
| 6 | Gap | ||
| 7 | SPKR RHS (or LHS) | Green | Speaker output signal for right or left (I don’t remember) |
| 8 | AMP OE | Brown | Amplified enable, when the computer is working, it sets it to +5V, it is connected to the standby pin 7 of TDA7375 through a resistor |
| 9 | AMP RTRN | Pink/Black | Input audio signal shared ground |
| 10 | AMP LHS (or RHS) | Pink/Transparent | Input audio signal left (or right – I don’t remember) channel |
| 11 | AMP RTRN | Brown/Black | Input audio signal shared ground |
| 12 | AMP RHS (or LHS) | Brown/Transparent | Input audio signal right (or left – I don’t remember) channel |
When there is an error, like speakers are shorted to the power ground, TDA chip will drive the standby pin 7 to 2V instead of 5V, that is input to it from AMP OE and will set the diagnostics pin 10 to low impedance (this pin is a hanging open collector, so may be harder to read).
Power Supply Unit
Delta Electronics DPS-150GB-1
Subwoofer Unit – Reassembly
