Thread

Powerbook G4 VGA not powering up

· Hardware · 10 posts · Feb 12, 2009 — Feb 23, 2009 View original thread ↗

#1 Thu, 12 Feb 2009 - 16:16

I had an instructor bring me a Powerbook G4 that won't power up. I tried resetting the PMU and taking the battery out, as well as re-seating the RAM.

The charger light in the back is always amber...

Any ideas?

#2 Thu, 12 Feb 2009 - 19:31

If it's always on "I'm charging!" amber, then it sounds like something might be really wonky with the PMU. Do you have another TiBook that you can try the battery and/or power cord out with, just to make sure it's not either of those?

#3 Thu, 12 Feb 2009 - 19:43

if you need parts, I happen to have a TiBook VGA bottom that I can let go for $50 w/ shipping in the USA. All it's missing is the screen and HDD, but if you want, I can ship it out to you.

I got it along with a TiBook 1Ghz that needs a screen.

The board in the VGA is fine, it's just the hinges broke a while ago on it, and the screen doesn't work.

#4 Thu, 12 Feb 2009 - 20:02

I have another power brick at home, so I'll try that. The verbage was "If you can get this running, great. If not no big deal..."

#5 Thu, 12 Feb 2009 - 21:02

This is likely an easy fault to fix.

Simply remove the bottom case, move the DVDROM drive, and disconnect the PRAM battery (3-wire connector) from the PMU. Reassemble, and the machine should work just fine, aside from no longer keeping date/time when the battery and AC are removed.

#6 Thu, 12 Feb 2009 - 22:51

no go on that either - still solid amber on the power plug w/ no battery

#7 Fri, 13 Feb 2009 - 22:01

Well then, that's not good. With any luck, it may just be a bad PMU; they were replaceable on those models, unlike the DVIs and later.

Or it could be a random logic board failure. I had a 500MHz model that was working fine, then it started to lock up hard before refusing to boot. The only working solution was replacing the logic board.

#8 Mon, 16 Feb 2009 - 15:53

One other point... Does the PB G4 need a PRAM battery to run? I found a replacement at OWC, but I want to be sure that it needs a good PRAM battery in order to start

#9 Thu, 19 Feb 2009 - 00:50

One other point... Does the PB G4 need a PRAM battery to run? I found a replacement at OWC, but I want to be sure that it needs a good PRAM battery in order to start

No. I recently acquired a Titanium PowerBook G4/400 that wouldn't boot, and the problem was a dead PRAM battery. I disconnected it, closed the PowerBook, pressed the power button and it booted just fine. So now it's running with the PRAM battery disconnected and there are no issues, apart from the fact that when left without power (no AC adapter, no battery), it doesn't keep the right date/time -- but since I keep it always connected to the Internet, it doesn't matter.

By the way, the other day out of curiosity I opened the other TiBook I have (a 500 MHz model) and I found out that the previous owner had removed the PRAM battery entirely. Hah.

HTH,

Rick

#10 Mon, 23 Feb 2009 - 15:08

Looks like completely disconnecting the pMU did wonders! It boots now!