Q: IBook G4 Will not turn on.

For my PowerBook, the main battery and backup battery serve the same purpose (of maintaining its PRAM and other key settings).  It only needs one of them to be working for my PowerBook to start up properly, which is why I never bothered to pay for a new backup battery.  Your model may work differently. 

If you think that's the problem, it's not related to the RAM installation.

When I did an Internet search on "ibook g4 backup battery," many of the resulting links said iBook G4 does not have a backup battery; it uses a capacitor to maintain PRAM settings for a few minutes if the main battery is swapped. 

Unfortunately, I don't have any other suggestions.

I requested (yesterday) to have your topic moved to the iBook forum category, after I realized that it was originally posted in the Older Hardware category, which is not visited as much by forum users who own iBooks, compared to the iBook category (which is specifically for iBook).  But this thread was already quite long by that time, and new readers may not bother reading, because it already has so many posts.

So, you may want to summarize what you have learned so far about your situation, and post a new topic here, in the iBook forum category.  Then, more users who actually own iBooks are likely to read it and reply with useful info.

And now it appears alongside this, here:

IBook G4 Refusing to turn on.

There is a capacitor or other device that keeps the settings in PRAM held over

for a time, while rechargable battery is removed or swapped for another. If the

iBook G4 is left with dead battery or no battery for too long, it may be possible

to charge the main battery, and if left to charge much longer, the capacitor may

also see some charge. To replace that capacitor requires a service technician.

Not just a plumber with blowtorch, or handyman with soldering iron; of course.

Built-in Memory    256 MB

Maximum Memory    1.25 GB

Memory Slots    1 - PC-2100 DDR266 200-pin SO-DIMM

(PC-2700 supported; however it will run at only 266 MHz)

A quality memory chip for this model iBook G4 from reputable vendor

since the older slower 266MHz RAM is not worth stocking, they offer

the faster 333MHz speed RAM of correct specs instead...

512MB PC2700 DDR 333MHz CL 2.5 200 Pin Low-Profile SO-DIMM

512MB PC2700 DDR 333MHz CL 2.5 200 Pin Low-Profile (non-stacked) Memory

module for all PowerBook G4 'Aluminum' 12", 15" & 17" Models, all iBook G4s,…

Mfr P/N: OWC2700DDRS512A | MacSales.com SKU: OWC2700DDRS512A

1.0GB (1024MB) PC2700 DDR SO-DIMM 200 Pin Memory Module

1.0GB (1024MB) PC2700 DDR SO-DIMM 200 Pin Memory Module 128x64 CL 2.5

for all PowerBook G4 'Aluminum' 12", 15" & 17" Models, all iBook G4s, iMac G4

The iFixit guides and/or original Apple Service Guide for iBook G4 (in PDF) may

be helpful in some aspects of this. I've owned first edition 'snow' iBook G3 500

12-inch; & have: last edition iBook G4 1.33 12-inch, 12-inch PowerBook G4 1.5;

+ first model edition MacBook1.1 1.83 coreduo 13-inch. Owned dozens of Macs.

The correct memory chip is the proper part number, if not that, the PC2700 as

stated would work; but at the slower supported chip speed. (The suggested

PC2700 DDR is same chip iMac G4 USB2.0 model uses in 'user slot' upgrade.)

Could be a static charge or other issue has resulted in hardware damages.

The internal structure and access into these models adds issues for the end

user to attempt to repair or upgrade internal components. Level: Difficult.

Another issue may be the DC-in Board. The powerbookmedic site shows part

numbers and sometimes has many parts. Also repair guides, etc.

Anyway, I've no further useful input on this topic; anyone reading the later thread

should look into this one also. Details being what they are, may not all be present.

{Thank you for advancing this discussion, the Hosts relocated it alongside new one.}

In any event...

Good luck & happy computing!

The appearance of this failed capacitor does not need to have

an outward one of damage. - They fail to hold a charge, is all.

However there may be other issues, since this one item is not

reason in and of itself, to stop the iBook G4 from startup.

The older white G3 and few G4 iBook models exhibited a

quirk whereby the graphic and other chips on logic board...

iBook G4 Logic board repair (Vreg chip solder joint repair)

www.xlr8yourmac.com/tips/iBookG4_vreg_repair/ibookG4_vreg_repair.htm

...solder joints that hold these items on the board, failed after

some time. Seems the heat then cooling cycles led to cracks.

Various topics may relate, in these results:

https://www.google.com/search?q=ibook+g4+logic+board+shim

https://www.google.com/search?q=ibook+g4+logic+board+replacement

This had been covered online for several years; enterprising

users tried various things, some used shims internally to push

against the failed solder area (non-conductive filler) and inside

the case. This worked in some instances. Others chose to take

entire iBook G3/G4 (white) apart & to re-flow solders. A heatgun

was sometimes satisfactory toward this end.

Items on the logic board that are not failed, may be adversely

affected by heat in general. They were not subject to high temps

when these boards were assembled - in their entirety. Or if a

high temperature was to be endured, it was a spot-heat from an

electronic workstation designed to instantly heat small areas.

{iMac G5 graphic cards were 'baked' in a kitchen oven, by some

users who DIY this issue, where that part had bad solder joints.}

Anyway, the model series is subject to a few widely known issues

and as they age, their usefulness is limited by later technologies.

A good used restored MacBook (early 2006-2010) is a better bet.

These are available for much less, & are better suited to daily use.

Repair companies such as powerbookmedic, wegenermedia & other

can be a source for units that've seen repair & have limited guaranty.

Good luck in this matter...!

There need not be any outwardly physical evidence of an internal electrical

failure of components in most devices. Even those 'cracks' which some had

found to be a cause of failure, were sometimes impossible to detect under

magnification... The electrical impulse was simply degraded enough to not

allow the units to work correctly.

Because the problem may have not been just the incorrect memory module

installed, troubleshooting should always be performed using the proper and

known-good replacement parts, of any thought to be defective. Care in the

handling of the assemblies involved is crucial to success.

The solder information given has many details to read through and short of

microscopic inspection by professionals who have workstations for use in

the process of micro-soldering logic boards & graphic cards, the end user

with a bright light and magnifying glass would be hard pressed to see the

worst ones. The kind where a compression technique may work can be less

than a decimal fraction of a hair thin, the crack. So little pressure can make

a connection; or a little delicate solder (as shown in previously linked pages.)

However if you choose to try & use incorrect parts in a sophisticated and

highly engineered device, no amount of second-guessing can fix any of

the secondary damages you may inadvertently cause to rest of the device.

*Also, careful handling of all components does not mean you may be free

of issue due to a failure while disassembly or reassembly; items that were

not cause of the original failure, can be suspect later on should it fail again.*

About the DDR vs DDR2 (SO-DIMM) memory chips, or other non-interchange-

able memory modules -- that are intended for use in specific products, only...

Variants of 200-pin SO-DIMMs

The 200-pin SO-DIMM can be of the types DDR and DDR2. In both cases the notch is

located at one fifth of the board length (20 pins + notch + 80 pins), but in DDR2 the

notch is located slightly closer to the center of the board.

These two types of memory are not interchangeable. The different notch locations are

designed to prevent cross-installation, aiding at the same time in visually identifying

200-pin SO-DIMM modules.

This variance is designed to prevent coupling of memory and controllers of different

DDR generations due to electrical incompatibility. DDR SO-DIMMs operate at 2.5 V

while DDR2 SO-DIMMs operate at 1.8 V - when both are of 200-pin, read the specs.

•Are DDR, DDR2 and DDR3 SO-DIMM memory modules interchangeable?

http://acer.custhelp.com/app/answers/detail/a_id/2178/~/are-ddr,-ddr2-and-ddr3-s o-dimm-memory-modules-interchangeable%3F

FOR GUIDANCE ONLY -- HEIGHT OF MODULE MAY VARY -

SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE

•Integral SODIMM Memory Guide (explains & shows differences; physical & electrical)

http://www.integralmemory.com/sites/default/files/uploads/pdf/INTEGRAL-SODIMM-GU IDE.pdf

•About SO-DIMM (dual inline memory modules) wikipedia:

https://en.wikipedia.org/wiki/SO-DIMM

Should anyone follow this thread, they too can see how most any technical issue

can be harder to troubleshoot when non-compliant parts are mistakenly installed.

In any event...

Good luck & happy computing!