PMU Reset

nanco wrote:
I have a 14" G4 1GHz iBook. It will not run off the battery, which is brand new. The system recognizes the battery, will attempt to charge it. However, it does not seem to be able to communicate with the battery because it sees it as charged to 0%. Yet, the charging part of the hardware sees it as charged because the amber light goes off after a few minutes since the battery is fully charged. So if I remove the AC power, the computer just goes dead after a few seconds. I tried to reset the PMU but it does not take. The date and all other parameters remain the same.

I checked the battery connector board and there is continuity in all the wires from the battery terminals to the motherboard.

I cannot test further because I don't have a schematic. I am used to repair my own electronic equipment as I am ham operator (WB2VAE).

I believe the PMU IC or a component leading to it, became defective.

Can anyone, kindly,

1. Confirm my diagnosis
2. Provide me with a schematic
3. identify where the PMU IC is located.

Thank you.

Nick

The machine is out of warrantee. So please don't tell me to get a new motherboard.

============


*Nick: *

With a problem of this amplitude, I'd work it systematically (and would agree it's best to avoid the ionospheric cost of a new motherboard...;):

I'd run the Hardware test that comes with your system - it should identify many of these problems. If you don't have a separate 'Hardware test ' DVD the relevant software will be on the OS Disk - e.g. on the Leopard Boot/Install disk #1 (I seem to recall that you access it by booting with the DVD inserted and holding down the 'D' key... but I'd check that...). Other Apps/Tools like 'Tech Tool Pro' - which is what Apple ships as part of 'Applecare', their extended Warranty deal - also check many motherboard subsystems. I can't say with certainty that either/any check the PMU specifically, however.



Maybe it's obvious but you didn't say that you'd verified that the battery Does have a full charge and is working correctly +in every respect+ - I think I'd look at the battery first - because, *in my experience* over 90% of such problems are caused by the Batteries themselves. ( I've had a High Frequency of problems with 'Smart' Lithium Ion subsystems - including the Li-ions Lyin' about their states/status)...

To Amplify:
1. try another, 'known quantity' battery
2. AFTER checking that the following is safe/sensible etc.(i.e. in view of 'smart' Mac to Battery Comms, charging etc...): Supply the battery terminals in the computer with the right flavour of DC power via a Battery eliminator/DC power supply adapter {As a Heroic Amateur, you must have such power supplies lying around..."I A.M. therefore I Think..". :)}

I tried to reset the PMU but it does not take. The date and all other parameters remain the same.

...
I'm not sure but don't think PMU and Date are related - that'd be PRAM if anything.... I don't know how you'd determine that a PMU reset had occurred - worth a search here ... and a smart Google or two.


As for specs/HW Diagrams etc. I'm pretty sure that the only place you'll get them is from a friendly Mac dealer...- try using warm, well-modulated Tones (but Google anyway). I doubt Apple are going to countenance giving you access.

I'd also suggest that most of this stuff is sophisticated microcomponent, multilayer circuitboardary and is unlikely to be fixable manually - NOT a matter of skill, just the nature of the Board - Apple & Dealers 'fix' most things with a boardswap themselves.


BUT: I'd still bet you a beer it's the Battery.


Hope that helps somewatt,

🙂

regards from Oz,




Wayne T

Nick,
This is from the manual for 1 GHz.
"The battery won't charge
1. Remove any connected peripherals.
2. Try known-good power outlet.
3. Try known-good power adapter and power cord.
Note:
Verify that power adapter connector glows amber or green. If the power
adapter light is green, turn over the computer and press the battery button. The
battery lights should glow green and stay on if the power adapter is operating
correctly.
4. Try known-good battery.
5. Reset the power manager by pressing the key combination Control-Option-Shiftpower.
Warning: Make sure you do not hold down the "fn" key when resetting the
power manager.
Warning: Resetting the power manager will permanently remove a RAM disk, if
present, and all of its contents. You will also need to reset the date and time
(using the Date & Time control panel).
6. Replace battery transfer board.
7. Replace logic board."

I believe the PMU IC or a component leading to it, became defective.

Maybe but run through all those procedures especially "known good battery" as Wayne suggests since that's also been my experience.

2. Provide me with a schematic

Never seen one. Apple tech do repairs at the board replacement level. No one's going to run a business repairing SMT parts on logic boards.

3. identify where the PMU IC is located.

Don't know exactly where it is on the 1 GB but settings by held by a super cap, .22 Farads @ 5V. I can show you where I suspect it is on the 1.2 GHz. Often close revisions have similar board layouts. Obviously the super cap is easy to find. The good pic is from the 1.2 and the blowed up one is from a 500 G3.

It's a microprocessor that controls power, PRAM, Time and Date doesn't say it on the 1 GHz documentation but older stuff says:
"The PMU (Power Management Unit) is a micro controller chip that controls all power functions for the computer. The PMU is a computer within a computer. It has memory, software, firmware, I/O, two crystals, and a CPU. Its function is to:
• Tell the computer to turn on, turn off, sleep, wake, idle, etc.
• Manage system resets from various commands.
• Maintain parameter RAM (PRAM).
• Manage the real-time clock.
Important: The PMU is very sensitive and touching the circuitry on the logic board can cause the PMU to crash."
That sounds like CMOS eh?

Look at the pics in my post in the Forum : "Power, Battery and your iBook G3 (Dual USB)":iBook G3 800mhz powers & starts up, after a shutdown it won't power up Shimshak Studios

Email me if you need more.

Richard

Message was edited by: spudnuty

Nick

Addendum:
The chip that controls the power management is a PMU99 (Apple Designation). Googling that I found:
http://everything2.com/index.pl?node_id=1325401
Which says:
"The power management unit in Macintosh computers is an independent Mitsubishi M16C/62F microprocessor. The Apple name for the unit is the PMU99. This little low-power embedded microcontroller controls the parts of the Mac that have to operate while the CPU is turned off (or suspended).

Because it's also a convenient chip with lots of I/O pins, it's also often used to control blinkenlights and do odd jobs in the Mac's main package. On a PowerBook, the PMU99 provides an ADB interface to the internal trackpad and keyboard (those devices aren't USB), as well as controlling the caps lock, num lock, and sleep indicators. (Specialized circuitry is used to make the sleep indicator pulsate - if you know how to access this, please tell me!) It's also responsible for charging batteries and turning things on and off on the motherboard.

The PMU99 is especially interesting in Open Firmware because it controls so much. The methods wink and winks cutely blink the sleep indicator. It's also the interface to the backlight. Of course, being a power management unit, it also controls shutdowns and restarts, both manual (because it owns the power button) and timed automatic (because it is the real-time clock). Open Firmware knows the PMU99 as a node named "via-pmu." "

Wow!

Richard