PowerBook G4 400 to 500


Start

DISCLAIMER: You shouldn't do this to your PowerBook. Period. This information is for educational and entertainment use only. If you actually follow these procedures it will void your Apple Warranty. If you follow these procedures you may break your PowerBook. If you break your PowerBook, well... we warned you.

Step 1

Preparation:
  • Start with a known working, stable machine.
  • Keep a clean, organized, static free work surface.
  • Unit powered off, main battery removed. (Picture 1)
  • Remove all 8 cross point screws on case bottom, Phillips #1. (Picture 2)
  • Remove Bottom Case(It's a slide-lift maneuver - we start by 'breaking' it loose by applying a slight pressure on the thinnest edge of the battery bay. Break it loose, slide it about 1/16" away from the I/O ports, then slide/lift while hinging it on the front edge.) (Picture 3)
  • The bottom case lifts up and then towards you. (Picture 4)

1. Battery Removal..2.

3. 4.

Step 2

Multiplier Identification:
  • Find the set of surface mount jumpers in the upper left hand corner of the circuit board. (unit face down with I/O ports away from you.)
  • There will be a group of jumpers - R217, R221, R225 - located near the bottom case screw stud post. (They're actually zero ohm resistors)
  • Don't confuse the silk screen labeling with the jumper set indicated by R218, R222, R226. Follow the white line from R217, R221 and R225 as illustrated by the red circle in the image below.
  • The PC Board silk screen is offset a bit from the actual jumper mounting pads.

1. 2.

3.

Step 3

Resistor Installation:

This part of the procedure is where soldering skills are essential. It will take a steady hand and VERY careful use of a soldering iron. We use a special soldering 'tweazer' to lift the resistor and move it to the new location. Flux might make this easier for pencil type soldering irons. Three special precautions: 1.) Don't loiter with the soldering iron on the main logic board - cook it and your board is toast!, 2.) accidentally fracture the resistor and, uhh...well, your board is toast, 3.) Drag the iron or overheat it and lift a trace and - you guessed it - your board is toast.

  • The PLL Multiplier is derived from the installation(or removal)of the jumpers in this set.
  • On a 400Mhz the jumper is installed at location R221.
  • On a 500Mhz the jumper is installed at location R217.
  • This image shows the jumper, after the move, installed at location R217(500Mhz)
  • * All you have to do to change a 400Mhz machine into a 500Mhz machine is to move the jumper from R221 to R217.

Step 4

Pre-Assembly testing:
  • Test boot the machine by reinstalling battery or connecting ac adapter.
  • Check the system profiler to confirm speed.
  • Be aware of the open traces on the back of the unit - don't set the unit down on your workbench, screws, tools, etc. Lay unit on it's side to protect the main logic board.

Step 5

Sit back and enjoy:
  • If running at 500mhz - shut it down and reassemble the bottom case.
  • You just saved about a $1000!(Compared to an Apple Store finished goods part number selection of the 500Mhz SKU...or about $400.00 if you only choose to change processor speeds...still a value.)
Conclusion

We're just hardware guys and wanted to speed bump our G4/400's so they'd feel at least as fast as our G3/500's felt before we ditched them(Doh!). I expect that there are other bus/processor speed combo's that can be derived from the PLL Multiplier circuit this procedures outlines, but we didn't bother going any further - jumping from 400Mhz to 500Mhz is a great increase and we're happy to have it.

Heat doesn't appear to be an issue, so I wonder what kind of processors Apple is building into these machines, or why we can get away with such a big jump(so far). Of the several we've done, all are operating at finger-touch acceptable temperatures(All the 'gauge' products I've tried report bogus temps, if anything at all) and there have been no adverse affects that I can detect...machine seems rock solid. Motorola has an errata describing the issue of 35-55deg discrepancies in the thermal assist unit, which is responsible for reporting junction temps.

We've included an email address below if you have further information to contribute, but please don't expect a response - and please don't ask us to fix your machine if you break it (Although, if you're really in a bind we'll take a look at it -but we're an Apple Authorized Service Provider so don't expect us to cover a fix under warranty!)

Rich Voelker, Voelker Research
Michael Kimbrell, Service Coordinator

Want to relay your results?

Side Note: Powerbook G4 500mhz Stock to a 550mhz - Move Jumper @ R218 to R222

3/29/01 - 6:00pm MST

Apparently there have been parallel discoveries on this topic in Japan. For a more detailed, technical view including bus speed hacks, check out this site in Japanese.(Alta Vista translation might be helpful)

3/29/01 - 10:19pm MST

Comparisons between stock 400Mhz and stock 500Mhz units to be slightly different. The stock 500Mhz units have what appears to be a slightly beefier heatsink/pipe configuration. Unable to confirm this on a second 500Mhz.

3/30/01 - 9:00am MST

Added image to clarify/correct the resistor labeling.

3/30/01 - 11:30am MST

Added link to Motorola site which discusses the Thermal Assist Unit on MPC7450 CPU's reporting temperatures 35-55 degrees lower than actual. See Errata 12

4/01/01 - 11:55am MST

Jumper resistor values confirmed to be 0(zero) ohm, aka - just a jumper.

4/02/01 - 9:00am MST

First successful upgrade performed using only a 'solder bridge'. By using a solder-bridge, rather than trying to reposition the Zero Ohm jumper, at the 500Mhz position(R217) heat stress and upgrade times can be reduced. It's also much easier to do. A better method. (You still need to pull the jumper from position R221)
© 2004 Voelker Research Interests, Inc.