Power lights on G4 AGP is continuously on

Discussion in 'PowerPC Macs' started by hasanito, Jun 4, 2010.

  1. macrumors newbie

    hasanito

    Joined:
    Oct 8, 2004
    Location:
    Perth, Australia
    #1
    G'day
    I've just picked up a G4 (450MHz) AGP from a friend and trying to get it to work. However I need a bid of a help to even start :confused:

    I've went through the usual battery reset procedure word by word, as listed at apple support page.

    The problem is, as soon as I connect the power cable, the power lights on comes on and stays on. This is before even pressing or turning anything on.
    If I press on the power lights, still nothing happens, no fan, no noise nothing... just the power lights are continuously on...

    any help or suggestions?
     
  2. thread starter macrumors newbie

    hasanito

    Joined:
    Oct 8, 2004
    Location:
    Perth, Australia
    #2
    I've tested the PSU and it's working, following the suggestions at apple support forum. Replaced the front power-on unit with an another spare one and this time power light didn't light up at all.... so I'm not sure if this an indication of another problem or just that the spare power on unit is the faulty one...!!!
    I will now remove the PRAM battery for overnight and see what happens in the morning.
     
  3. macrumors 68020

    zen.state

    Joined:
    Mar 13, 2005
    #3
    Good news about the light no longer staying lit when off. You certainly don't need to leave the battery out all night. 15 minutes is plenty. After that press the reset button right by the battery but be sure to press it just once.
     
  4. thread starter macrumors newbie

    hasanito

    Joined:
    Oct 8, 2004
    Location:
    Perth, Australia
    #4
    I've pulled the Pram batter overnight and still no luck!
    I've got two Pram batteries in my hand and they may both be dead!!

    If Pram batteries are low or just plain dead, what would be the actual symptoms?
    Could that be the cause of nothing happening with the G4?
    Is there another way to fault finding on G4?
     
  5. macrumors 68020

    zen.state

    Joined:
    Mar 13, 2005
    #5
    The bettery could very well be the cause. I'm pretty sure that the only Mac tower in the last 10-12 years that will boot without the battery is the B&W G3. You need one on yours.

    Another thing to keep in mind is if you press the board reset button more than once within 2-3 seconds it can drain the battery.
     
  6. thread starter macrumors newbie

    hasanito

    Joined:
    Oct 8, 2004
    Location:
    Perth, Australia
    #6
    could they be recharged? or just needs to be replaced?

    I'll try to beg/barrow/steal a multimeter to see how much charge in them, I think their max charge level is 3.7v...
    at what charge level they'd be useless?
     
  7. macrumors 68020

    zen.state

    Joined:
    Mar 13, 2005
  8. macrumors 65816

    CubeHacker

    Joined:
    Apr 22, 2003
    #8
    The battery does not need to work at all for the computer to boot. The only issue with a dead battery is that the computer will lose clock settings if unplugged from the outlet. I have an iMac G3 who's battery is dead and i'm just too lazy to replace it. The machine works fine, but will lose clock settings if unplugged.
     
  9. macrumors 68020

    zen.state

    Joined:
    Mar 13, 2005
  10. macrumors 68040

    666sheep

    Joined:
    Dec 7, 2009
    Location:
    Poland
    #10
    With all respect to you - As a PPC geek, you should know, that it's completely false ;). Every G4 and G5 will boot without battery just fine, even better than with dead (or almost dead) one. I can tell it from my personal experience with G4 and G5 that i owned or repaired (total amount near to 200+).
    CubeHacker is right.
     
  11. macrumors 68020

    zen.state

    Joined:
    Mar 13, 2005
    #11
    I was simply speaking from personal experience from owning 3 sawtooth, 2 gigabit eth, 1 quicksilver and 2 MDD. The digital audio is the only tower I have never owned. None of them booted without batteries. The MDD seems the most reliant on the battery of all the towers.

    Not sure what we are doing differently but in my world what I said is true.
     
  12. macrumors 68020

    zen.state

    Joined:
    Mar 13, 2005
    #12
    Well what do you know.. I just tried booting my sawtooth without battery and boom! It booted?

    I guess in the past whenever I was dealing with the battery (which wasn't often) there was something else stopping it from booting.

    I humbly stand corrected. The geek torch goes to cubehacker and 666sheep on this one. :)
     
  13. macrumors 68040

    666sheep

    Joined:
    Dec 7, 2009
    Location:
    Poland
    #13
    Edited: it was hard to believe to me... THX for the torch :D

    Back to the OP problem:
    - how did you checked PSU (link goes to nowhere)?
    - double checked all cables inside?
    - when you open case and push power btn is there red light on logic board?
    - is fan completely not run or is it tries to spin and stops?

    Post more details about what you do and what you get.
     
  14. macrumors 68020

    zen.state

    Joined:
    Mar 13, 2005
    #14
    I'm not American my fellow PowerPC loving friend. Canadian.

    In all those Macs I don't think I had to deal with batteries in each one. The only thing I can think of is there was something else stopping the booting. One of the times it turned out to be the psu not having a fan plugged in to it's 2 pin connector. I replaced the psu fan in my sawtooth and first tried to run it on molex with the wire sticking out and running down the side. Once I plugged the fan into thew 2 pin it booted fine. I went with molex first as I thought 2 pin might not alwats run the fan at max. It's a very good double ball bearing fan meant for constant high rpm.
     
  15. macrumors 68040

    666sheep

    Joined:
    Dec 7, 2009
    Location:
    Poland
    #15
    Yes, yes, edited it completely, see above :) BTW, i meant America (North one precisely) as continent, not States ;) ofc.
     
  16. thread starter macrumors newbie

    hasanito

    Joined:
    Oct 8, 2004
    Location:
    Perth, Australia
    #16
    uhm... the link is dead.. dunno what happened there but...
    I've basically unplugged the psu from motherboard and connected the green cable o/p with one of the black (earth) o/p cable and connected the power. The psu worked and fan was fanning away :)... thus psu works -tick!

    I've checked the cables inside as much as I could and they all seem to be connected.

    After the power button pushed, there is no red light on the logic board either.

    The fan does not run at all, in fact nothing in the G4 does any kind of sound!!
     
  17. macrumors 6502

    Joined:
    Mar 16, 2007
    #17
    Check for bad resistors or diodes near the PSU connection on the board, you'll see black smoke marks around them. If it's a 0 ohm resistor, you're in luck because you'll you can just bridge the two pads. It won't hurt to check the voltage regulators, they're labeled SC2602S. Also, check mosfets or capacitors for a bulge.
     
  18. macrumors 68040

    666sheep

    Joined:
    Dec 7, 2009
    Location:
    Poland
    #18
    PSU seems to be OK then. It will be difficult do diagnose without working parts.
    Inspect all possible parts for visual damages (like kbfr08 said), including those both front panel modules. Also open PSU and inspect it's capacitors (unplugged ofc ;)). It might work without load but when it must produce some power, it fails (just a guess).
     
  19. thread starter macrumors newbie

    hasanito

    Joined:
    Oct 8, 2004
    Location:
    Perth, Australia
    #19
    thanks
    I've replaced the Pram battery with a new one and it didn't make any difference.
    I may try inspecting PSU as suggested but what am I looking for? just if there is any burned damaged capacitors??

    I found this link
    http://www.scribd.com/doc/21536787/...ad-2-5-Dual-2-0-2-3-Ghz-Service-Repair-Manual
    to use as a guide to check the m'board.

    I'll also take apart few parts PSU/front power panel/ram/videocard etc... to a friends place and test them on his G4
     
  20. thread starter macrumors newbie

    hasanito

    Joined:
    Oct 8, 2004
    Location:
    Perth, Australia
    #20
    After going through all the peripherals and parts on a friends G4, I traced the problem to the faulty front power control panel.
    The one and the spare are both seem to be faulty!!

    Now I have to find a working one from somewhere!!
     
  21. macrumors 68040

    666sheep

    Joined:
    Dec 7, 2009
    Location:
    Poland
  22. thread starter macrumors newbie

    hasanito

    Joined:
    Oct 8, 2004
    Location:
    Perth, Australia
    #22
    One more Mac saved from oblivion and put to good use!!
    I found a part for the front power panel and it works like a charm..
    Already installed Tiger and thinking about using it as a second computer and file server...:D
     
  23. macrumors 68040

    666sheep

    Joined:
    Dec 7, 2009
    Location:
    Poland
    #23
    Good to hear it's up and running.
    Regards for mactalk.com.au ;) (blacksheep)
     
  24. macrumors 68020

    zen.state

    Joined:
    Mar 13, 2005
    #24
    Good news! The power button panel is a strange part to stop working.

    I'm sure you will get years out of it as a file server which I think is a great use for it if you don't want to upgrade it. These Sawtooth towers are the most reliable Macs that Apple ever made in my experiences.
     
  25. thread starter macrumors newbie

    hasanito

    Joined:
    Oct 8, 2004
    Location:
    Perth, Australia
    #25
    just one question...
    a hdd I had bought much earlier, 10.3.9 Panther-Server installed on it already.
    I'm not sure upgrading whether to 10.4.8 Tiger or leave it as it is.
    Which one is better, Panther-Server or Tiger on Sawtooth?
     

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