[onlyone-jc]

Hi.

A friend of mine has a last-gen 17" Powerbook, and it has been acting up a little.

It started to automatically boot up in to Open Firmware when it was switched off, but would boot as normal once 'mac-boot' was entered in to the prompt.

However, recently it has stopped switching on, and so I've been reading around on the subject for them.

Do you think it could be that the PRAM battery has gone flat?

If so, where can they purchase one (in the UK, or from someone who ships to the UK fast)?

I've been looking on ifixit.com, and it seems easy enough to fit it, so it's just a question of getting hold of a new one. Any ideas?

Thanks.

[rehoot]

If the "PRAM battery" dies and the computer is unplugged, I think the main indicator is that the system date is reset to the default value. Is this happening?

When you say "open firmware" do you mean that you are being asked to select the boot volume? If that is the case, be sure that you have all the files archived on an external volume, then try System Preferences->Startup Disk and select the startup disk to reset any problem that might have arisen.

From what I know of 17" PowerBook PRAM batteries (by listening to the guy ahead of me in line at the Apple store) is that the PRAM batteries very rarely die. If it is dead, it almost always means that the main battery has not been fully charged. The solution is to plug the computer in to charge the batter for a long time (overnight or maybe a full day?) with the computer off to be sure that the main battery has had a chance to be fully charged. If this cures the problem, then the issue was lack of sufficient charging of the main battery. If this doesn't cure the problem, the maybe there is another problem or there is a slight chance that the "PRAM battery" has failed.

[onlyone-jc]

Originally Posted by rehoot 

If the "PRAM battery" dies and the computer is unplugged, I think the main indicator is that the system date is reset to the default value. Is this happening?

Yes, this has happened. However, as I stated above, it won't turn on now. I opened it up just before, re-seated the PRAM ribbon cable in to both slots (the one on the PRAM circuit itself, and the one on the Logic Board), put it back together, re-seated the keyboard/trackpad ribbon cable, and then re-seated the RAM, and it started working again. Then, once I had shut it down, it wouldn't turn back on again.

It's quite strange, but this is what has lead me to start doubting the PRAM Battery.

Originally Posted by rehoot 

When you say "open firmware" do you mean that you are being asked to select the boot volume? If that is the case, be sure that you have all the files archived on an external volume, then try System Preferences->Startup Disk and select the startup disk to reset any problem that might have arisen.

No, it's not asking to select the boot volume. It just shows the Open Firmware prompt, and states to type 'mac-boot' to boot as normal, or to type 'shut-down' to shut it down.

I tried 'reset-nvram', and 'reset-all', but it doesn't seem to have made a difference.

Originally Posted by rehoot 

From what I know of 17" PowerBook PRAM batteries (by listening to the guy ahead of me in line at the Apple store) is that the PRAM batteries very rarely die. If it is dead, it almost always means that the main battery has not been fully charged. The solution is to plug the computer in to charge the batter for a long time (overnight or maybe a full day?) with the computer off to be sure that the main battery has had a chance to be fully charged. If this cures the problem, then the issue was lack of sufficient charging of the main battery. If this doesn't cure the problem, the maybe there is another problem or there is a slight chance that the "PRAM battery" has failed.

The main battery is fully charged, and I'm fairly sure that once charged, leaving the mains adapter plugged in makes no difference to its charge. However, maybe leaving the mains adapter in continues to keep the PRAM battery charged? I'll leave it in for a while, and give it a go.

Maybe the reason it has been automatically booting up in to Open Firmware (even with the lid closed) is because all of a sudden, the PRAM battery gets enough charge to regain some form of settings, due to mains power being present?

Thanks.

[onlyone-jc]

Originally Posted by onlyone-jc 

The main battery is fully charged, and I'm fairly sure that once charged, leaving the mains adapter plugged in makes no difference to its charge. However, maybe leaving the mains adapter in continues to keep the PRAM battery charged? I'll leave it in for a while, and give it a go.

Maybe the reason it has been automatically booting up in to Open Firmware (even with the lid closed) is because all of a sudden, the PRAM battery gets enough charge to regain some form of settings, due to mains power being present?

Well, I've left the power adapter in for most of the day now, and it still won't come on. However, the main battery lost a little charge overnight, and when I plugged the power adapter in this morning, it began to charge the main battery for around twenty minutes or less.

I'll try re-seating the ribbon cables and RAM again later, and see if it decides to come back on again, like it did yesterday.

Any other ideas?

Thanks.

[onlyone-jc]

Okay, so it just decided to come on again (all by itself, with the lid closed). It started up with a loud tone and the fans at full speed. I opened the lid quickly, and it presented me with the Open Firmware. I typed in 'mac-boot', and it booted in to OS X and operated as normal. However, after a few minutes, I was presented with the shutdown dialog that you get when you press the power button. I canceled it, and decided to press the power button just to see if it was okay, and it didn't work. I opened TextEdit and tested every key on the keyboard, and they all worked fine. The trackpad also works just fine. I then shut down the computer (via the Apple menu), and was unable to turn it back on. So, it seems the power button has become faulty, rather than the PRAM battery, maybe?

Does anybody have any ideas what may be causing this?

Also, what would cause it to start up with a loud tone and the fans at full speed, then present Open Firmware?

Thanks.

[onlyone-jc]

Right, so I think I've finally figured it out. The power button wasn't working, so I began to wonder why. I wondered whether it thought the lid was closed, so I decided to repeatedly push the clasp lid button (on the front) to see if it was some sort of contact stuck inside; then hey presto, it came on as normal, no Open Firmware or anything. However, after shutting it down, I had to do the same in order to get it to start up again.

What can I do to the clasp mechanism inside in order to make it operate as normal? Any ideas?

Thanks.

Edit: I just tried the same method a few more times, and it seems to work, however it started up with the same tone and the fans spinning then went in to Open Firmware, then upon typing 'mac-boot' and booting in to OS X, the clock/date had been reset. Any ideas?

Thanks.

[rehoot]

Originally Posted by onlyone-jc 

Right, so I think I've finally figured it out. The power button wasn't working, so I began to wonder why. I wondered whether it thought the lid was closed, so I decided to repeatedly push the clasp lid button (on the front) to see if it was some sort of contact stuck inside; then hey presto, it came on as normal, no Open Firmware or anything. However, after shutting it down, I had to do the same in order to get it to start up again.

What can I do to the clasp mechanism inside in order to make it operate as normal? Any ideas?

The reset date would usually mean a bad PRAM battery, but the spontaneous booting is a mystery. You mentioned a bad power button, but the mechanical button itself shouldn't affect PRAM unless it powers on in the middle of the night (while unplugged) and drains the main battery and thereby lets the PRAM battery die. I'm wondering if you have some other type of problem in the power supply between the button and the logic board--and maybe multiple problems. The theory about the computer detecting the full charge initiating a boot might not be exactly right, but it might be in the ball park.

You could try to tweak the power save option to avoid sleeping when the lid is shut or when the power button is pressed. First review all the settings in System Preferences->Energy Saver. You can also review the settings in pmset from a Terminal window (Terminal is in Applications/Utilities). Read about the options for pmset using the Terminal command:
man pmset

Look at the pmset options for lidwake, powerbutton, acwake (wakes the machine when power source changes).



I would take it for service at this point if you can't fix it.

[onlyone-jc]

Is it safe to disconnect the PRAM battery internally, and run the machine without it? Just to see if everything works fine, and then at least we can either rule it out, or confirm that it's the culprit.

Thanks.

[rehoot]

Originally Posted by onlyone-jc 

Is it safe to disconnect the PRAM battery internally, and run the machine without it? Just to see if everything works fine, and then at least we can either rule it out, or confirm that it's the culprit.

Thanks.

I would guess so. I have run computers with dead PRAM batteries (one PC and one G3). There might be minor problems from the date being reset all the time (when the main battery also dies??). If you leave it plugged in, there should be no impact as far as I know.

We suspect that there is some power-related issue, To be extra super cautious (i.e. paranoid), it might be a good idea to treat the computer as a fire risk until it is fixed.

[onlyone-jc]

Do you think the computer will give a kernel panic? Since, disconnecting the PRAM circuit will also disconnect the right USB port.

Thanks.

[onlyone-jc]

It's the clasp, or latch, whatever you want to call it, as I previously suspected.

There's a small piece of metal that acts as a spring that sits behind the button that opens the lid. There's two contacts along the bottom edge of the main battery, with two spring-loaded rounded contacts that touch the contacts on the battery. If logic is telling me right, those contacts need to touch the battery in order for the circuit to made complete; power, or no power adapter. Since the button to open the lid touches one of the two spring mechanisms that hold these contacts in place each time it is pushed it and then released again, it seems that it may have worn the tension out of the right one (of which is the only one the button touches when pushed in). I used a small tool to push the spring-loaded metal contact back towards the battery compartment, in order to retain more tension in that direction, and thus a firmer connection to the contacts on the bottom edge of the battery, put it all back together, and everything now works absolutely fine. The power button works again, it seems as normal, and I haven't seen Open Firmware again.

I ruled the PRAM battery out by sleeping the Powerbook and removing the main battery. The sleep indicator light on the front remained lit and I was able to put the main battery back in and wake it back up to the state I left it in. The clock also kept its settings.

I've shut it down, have disconnected the mains adapter and closed the lid. I'll give it a few hours and see if it comes on by itself. If all goes well, it seems like it was indeed a power issue, and was an intermittent connection between the right contact and the battery.

Can anyone explain what the two contacts along the bottom edge of the main battery are? Are they the negative contacts? Or, maybe the earth contacts?

Thanks.