turn computer on, no display, and fans full speed...

Question

guitar guy Author

Level 2

327 points

turn computer on, no display, and fans full speed...

Hello.

I have a Power PC G5 quad running 10.5

I have the old apple cinema display with the adc to dvi adapter.

It has been running fine until....

Today, i had to unplug the display, and remove all usb attachments from the G5 and move the computer to have my room painted.

I just put it all back together, correctly, and when I power up the G5, the display does nothing, and i hear the copmuter power up, but after about 30 seconds, the fans start running full speed and don't stop.

And so without any monitor, i have to force shut down the computer (or let the fans run full speed for eternity...)

When I push the power button on the display, the power light within the button lights up, but goes dim when I release the power button. And the display never turns on.

I'm wondering what went wrong.

Any thoughts?

Thank you all!!!

PowerMac, Mac OS X (10.5.8), quad core

Posted on May 23, 2012 3:59 PM

Reply

Answer 1

Best reply

japamac

Level 7

24,400 points

May 23, 2012 5:12 PM in response to guitar guy

Sounds like the machine doesn't get to logic; processor function.

Start with the basics.

1- Reset the PRAM

Resetting your Mac's PRAM and NVRAM

2-Reset the SMU

How to reset the SMU on a Power Mac G5 - Apple - Support

3-Inspect for coolant leaks

PowerMac G5 Coolant Leaks/Repairs

4-Reseat the RAM

PowerMac G5 Memory Installation - YouTube

5-Reseat the graphics card

Installing Power Mac G5 Graphics Card

Of note: any diagnostic LEDs lit?

About the Power Mac G5 (Late 2005) diagnostic LEDs

Reply

Answer 2

guitar guy Author

Level 2

327 points

May 23, 2012 5:35 PM in response to japamac

thanks japamac.

Step #1 fixed the problem.

All i did was reset the PRAM, and everything suddenly worked.

Thank you!!

I forgot how relevant resetting PRAM still is....

Reply

Answer 3

japamac

Level 7

24,400 points

May 23, 2012 5:41 PM in response to guitar guy

I'm glad that it was easy.

This likely indicates that it is past time to replace the PRAM battery on your logic board.

Might pick up a new one.

Reply

Answer 4

guitar guy Author

Level 2

327 points

May 23, 2012 6:16 PM in response to japamac

hmm...ok.

is that easy to do?

I'll look it up online..... thanks again!

Reply

Answer 5

japamac

Level 7

24,400 points

May 23, 2012 6:36 PM in response to guitar guy

It's easy.

Look for the button battery on the board. note which side is up and replace it with one of these:

http://eshop.macsales.com/item/Newer%20Technology/CR2032/

Reply

Answer 6

guitar guy Author

Level 2

327 points

Jul 5, 2012 6:25 PM in response to japamac

hey japamac, it has happened again, and now, the PRAM won't reset. The fans go full speed, monitor doesn't turn on, and i have to force shut down. When I re-boot, the HD sounds as if it just waking up from sleep, not as if it's being re-booted. The Apple tone never sounds, and again, no monitor, and after 30 secs, the fans go full speed again. Anyway, i guess it's time to look at the PRAM battery........?

Reply

Answer 7

japamac

Level 7

24,400 points

Jul 6, 2012 2:47 AM in response to guitar guy

i guess it's time to look at the PRAM battery........?

Start there so as to eliminate the source of many evil gremlins......

You can reset the logic board by shutting down and disconnecting power to the tower (and monitor) for 15 minutes.

Reconnect power and try starting.

Reply

Answer 8

guitar guy Author

Level 2

327 points

Jul 11, 2012 12:06 PM in response to japamac

...so I reset the logic board and it didn't help, but hours later, it booted up and its been fine for 4 days now. Of course, the computer has been on that long. We haven't shut it down yet.

Reply

Answer 9

guitar guy Author

Level 2

327 points

Jan 28, 2013 9:47 PM in response to japamac

hmm...its doing it again. And the pram battery is only 6 months old.

I tried all your diagnostic steps (except for the battery) and nothing helped.

Reply

Answer 10

japamac

Level 7

24,400 points

Jan 29, 2013 2:33 AM in response to guitar guy

Boot to the OS X install disc (if possible).

In the window after selecting the language, from the Menu Bar/Utilities select Disk Utility.

Run "Repair Disk" on your startup drive.

Make note of any errors (if present).

If errors are repaired, run the repair again, then restart normally.

If the machine won't boot to the OS install disc, one would want tom try the AHT (Apple Hardware Test) from the original software install discs. Running the full battery of tests (extended) would be desirable.

Reply

Answer 11

guitar guy Author

Level 2

327 points

Jan 29, 2013 4:20 AM in response to japamac

Thanks jap but I have no monitor. The monitor doesn't turn on

Reply

Answer 12

japamac

Level 7

24,400 points

Jan 29, 2013 6:08 AM in response to guitar guy

The monitor doesn't turn on

Booting to the OS X Install disc?

How about the AHT? Do you have it?

Can you borrow a DVI monitor? That can help rule out the adapter....

Reply

Answer 13

guitar guy Author

Level 2

327 points

Feb 1, 2013 9:29 AM in response to japamac

jap, i can't get thge DVD drive door open. So i can't boot from the install disk. I boot the computer up and hold the eject button down on the keyboard, but nothing happens.

I also can't zap the PRAM like I did the first time i had this problem, and that had temporarily fixed the issue.

But now, I hold down command+option+P+R, and nothing happens. No "chime" sound (is that what we call it?). The fans go full speed after 30 seconds, and the monitor doesn't turn on.

I also can't boot into open firmware.

So the keyboard seems unresponsive.

I reset the SMU.

Is there a way to manually get that DVD drive door open?

Not sure if I can borrow a DVI monitor. I'll ask around....

I don't have AHT, but without being able to open the drive door, not sure what i would do...

Reply

Answer 14

japamac

Level 7

24,400 points

Feb 1, 2013 4:06 PM in response to guitar guy

guit, the drive door can be opened during startup by holding a mouse click.

Manually, pull the tower drive door cover open using a peice of tape and look for a smal hole to the bottom right of the tray. Using a straightened paper clip, insert the wire into the hole and once contacting the opening mechanism inside, push.

Once you have pushed the tray out a bit,,pull it open with your fingers.

Reply

Answer 15

guitar guy Author

Level 2

327 points

Feb 19, 2013 8:28 AM in response to japamac

it just started working again. Can't explain it, but i can't afford any repairs now anyway, so i'm just going to cross my fingers.

I should add that when i replaced the PRAM battery last year, i noticed that the clip that holds the battery in was not that tight on the battery. It was a little loose, so I might look at that should the computer start acting up again.

Thanks for your help everyone!

Reply