This page describes a repair attempt of an Apple PowerBook, 17“ 1.0GHz. The original fault was that the internal display did not work despite the presence of background light. The repair if this computer with multilayer circuit board has taken considerable time and painstaking efforts, especially because it's lacking schematic diagrams.
In the meantime the initial approach of repairing the logic board has been changed. Replacing parts made more sense than spending hours on troubleshooting onboard graphics. Prices on Ebay and other dealers are anyway reasonable.
After searching the internet a lot, it seemed that the mainboard (Apple calls it logic board) from the 1.0GHz model seemed to suffer quite frequently from the same problem. Therefore a better option seemed to be replacing the main board with that from a faster model, running at 1.33GHz. (This inhibited a few other differences as well, like Gb network instead of 100 Mb). Perhaps a more suitable title of this writing would be: upgrading a 1.0GHz 17inch PowerBook into a 1.33GHz PowerBook.

Searching the internet for more information about differences between the two models revealed a service manual from Apple, titled “PowerBook G4 (17-inch 1.33GHz) 16 September 2003”¹⁾. On page 2 it mentioned, in comparison with the 1.0 GHz model, the following information:

• Flex cable compatibility
  The sound and modem flex cables are not interchangeable with the original PowerBook G4 (17-inch) system. The main logic board will be damaged. The correct flex cables have the word “POWERBOOK G4 17” 1.33GHZ ONLY.”
• No L3 cache
  L3 cache is not used on this system. So unlike the previous model, there is no blue thermal pad on the logic board facing the keyboard.
• Thermal module interface
  Thermal gel is now used on the ATI Mobility Radeon 9600 graphics chip as well as the Intrepid chip. The thermal module is different from the previous 17-inch PowerBook. It has a different interface feature for the graphics chip and now has three heat pipes instead of one.

The information showed us, we would need two special flexcables and another thermal module interface. Therefore I ordered following parts at usedmac.com:

• 1 x 922-6065 G4 Aluminum 17“ Sound Cable (1.33GHz & 1.5GHz) only.
• 1 x 922-6066 PB G4 17” Aluminum 1.33/1.5/1.67 GHz Modem Flex Cable
• 1 x 922-6208 PowerBook G4 Al 17“ Heat Sink & Fan (1.33GHz & 1.5GHz)

It was difficult to find proper replacement thermal conductive material. Roughly measured, the distance between the processor and thermal module was about 0.8mm. The Intrepid 2 and graphics chip should use thermal conductive gel. After a long search on the internet, I choose following material:

• Thermal gel: A96AB, from T-Global Technology. Link:T-Global Technology Thermal Gel A96AB
• Thermal pad: Bergquist Gap Pad 2500S20, 0.040” (1.0mm). Link:Bergquist Gap Pad 2500S20

After using proper thermal conductive material, I transferred the 1.33 GHz logic board to the new thermal module interface. I noticed both the modem flexcable and the sound board cable showed different pin layouts. Without checking further I replaced the cables, and switched on the PowerBook. Unfortunately some smoke came out of the flex cable connector at the sound board. After removing the sound board cable again, the rest still seemed to work fine.

To solve the problem with the sound board, I needed more information about differences.

A scan of both cables revealed the following (click images for details. Pin 1 is marked with a 'V'):

Sound Board flexcable 1.0 GHz		Sound Board flexcable 1.33 GHz
logic board ← (pin layout) → sound board		logic board ← (pin layout) → sound board
3-6 ↔ 1-4		3 ↔ 1
1+2 ↔ 5+6		2+5+24+27 ↔ 2+5+24+27
8 ↔ 7		1 ↔ 3
30 ↔ 8		30 ↔ 8
28 ↔ 9		29 ↔ 6
24 ↔ 10		28 ↔ 7
21+23+25+27 ↔ 11+15+18+23		26 ↔ 8
20 ↔ 12		21+22 ↔ 9+10
18 ↔ 13		20 ↔ 11
17 ↔ 14		16-19 ↔ 12-15
15 ↔ 16		10-15 ↔ 16-21
16 ↔ 17		23 ↔ 22
19 ↔ 19		25 ↔ 23
22 ↔ 20		4 ↔ 25
26 ↔ 21		6 ↔ 26
29 ↔ 22		7 ↔ 28
7 ↔ 24		8 ↔ 29
9-14 ↔ 25-30		9 ↔ 30

From differences between both sound board flex cables, it was obvious the pin out around the sound board connector at the main board has differences. From a quick view at the 1.33GHz logic board for pins which carry power lines, it seems the (marked with a sticker showing PBG4 17“ 1.33GHz&1.5GHz) flex cable²⁾ pin out is correctly adapted at the logic board side. However, using this flex cable to connect to the 1.0 GHz sound board³⁾, the connections can not be correct. For example pins 12-15 at the 1.33GHz flex cable sound board side, carrying 5.0V, would make connection with the 1.0 GHz sound board at pin 15, which is GND. This explains the initial smoke, which melted some plastic at this pin.

The term schematic diagram is an exaggeration, but it shows in more detail the connections at the 1.0 GHz PowerBook specifically around the connection between sound board and logic board.
Please see the pdf file for my drawings.

The video graphics controller is a GeForce4 MX. This chip exists in four variants:

Other computers with the GeForce4 graphics controller are:

• Toshiba Satellite 1410/“1900-703”/2410/2430/“2450 3/9”
• Acer Aspire-RC900 http://www.mk-electronic.at/hersteller/PDFDokumente/Acer/Desktop%20System(DS)/Aspire/RC900.pdf
• Dell Latitude C840

See following link: DVI-connector