proskater123 Posted May 19, 2012 Share Posted May 19, 2012 So I am working on a mac g5. I have not worked on very many so my knowledge is limited. So here is the issues and steps I have taken to try and fix the issue. When the mac was brought in it would: Chime the mac boot up sound Not show any video fans will start normally but after awhile would spin up to full rpm What I have tried: Reseting the pram Reseting the pdu checked the onboard battery for 3.5 volts started without the battery tried new ram After some more diagnosing, the Mac will start once out of every 10 times it starts. (This is just a rough estimate. Not actual) Even when it does boot after about ten minutes it will freeze, and fans will be at top rpm. Then when I try to reset it, sometimes it will not boot with no mac chime, not boot with mac chime, or boot with mac chime. It is very random. I am very clueless as I have not had many times to work on a mac. What would you say is the problem? The logic board, cpu, pdu or something else? I have disconnected both hard drives and still received the same issue. Quote Link to comment Share on other sites More sharing options...
digip Posted May 19, 2012 Share Posted May 19, 2012 When is the last time the cmos batter was changed on the device? Can you boot off external media? Like a live linux disc or mac install disc? Just curious is it still has the same problem off live media. If so, something definitely hardware wise is out of whack. Quote Link to comment Share on other sites More sharing options...
proskater123 Posted May 20, 2012 Author Share Posted May 20, 2012 When it does boot it will boot to what I select. But it will not even show a picture most of the time. I checked the cmos battery and it had a full charge of 3.5 volts. Quote Link to comment Share on other sites More sharing options...
Infiltrator Posted May 20, 2012 Share Posted May 20, 2012 (edited) It sounds like you may have some hardware problem. 1) Is the power supply overheating at all? 2) Make sure the CPU Fan is sitting properly. 3) Make sure all cables are clean and in good condition! 4) If else fails, it could well be the CPU or Mobo, that's causing the lockups/freezes Edited May 20, 2012 by Infiltrator Quote Link to comment Share on other sites More sharing options...
proskater123 Posted May 20, 2012 Author Share Posted May 20, 2012 it does not seem to be heat because it will do the same thing right away when i turn it on. I could leave it running when it does not show anything then i will restart it and at times it will show something. Other times when I start it right away it will work. I can not find a pattern as to when it does work correctly. Quote Link to comment Share on other sites More sharing options...
digip Posted May 20, 2012 Share Posted May 20, 2012 (edited) But it does this even when trying to boot off other media, or only when booting from the HDD? What happens when booting while HDD unplugged from board? (Obviously no OS to boot, but wondering you get a blank screen still) Edited May 20, 2012 by digip Quote Link to comment Share on other sites More sharing options...
proskater123 Posted May 20, 2012 Author Share Posted May 20, 2012 Yeah. I still get a blank screen. When it will work after about ten minutes the fans will gradually reach top rpm and then the computer will freeze. Quote Link to comment Share on other sites More sharing options...
01000010 Posted May 20, 2012 Share Posted May 20, 2012 (edited) I would get one of the power supply tests that are like 5 bucks or sneak up to the computer shop and use theirs to make sure the power supply is good when you say no video does it show up on the network? If it does not show up on the network I would start checking the motherboard. If its on the network then you are just having a video card issue which goes back to testing that and the powersupply. Edited May 20, 2012 by leapole Quote Link to comment Share on other sites More sharing options...
proskater123 Posted May 21, 2012 Author Share Posted May 21, 2012 I personally would not think it was the video card because at times the mac would play the start up chime with no video, other times it would not play the start up chime both without video Quote Link to comment Share on other sites More sharing options...
digip Posted May 21, 2012 Share Posted May 21, 2012 I personally would not think it was the video card because at times the mac would play the start up chime with no video, other times it would not play the start up chime both without video So how does that rule out the GPU? Worth a shot looking into. Any hardware failure on boot, generally causes some sort of beeps. No beeps is usually worse than no post at all. But MACs are a little different than a pc, and I don't have enough experience with them. I've never owned one or taken one apart, but would gather, basics are still the same. Does this machine allow you to put a different GPU in? Quote Link to comment Share on other sites More sharing options...
barry99705 Posted May 25, 2012 Share Posted May 25, 2012 Which model G5 is it? Here's the troubleshooting steps for the June 2004 and Early 2005 models. Power-on LED illuminates when power button is pressed, fans spin, and boot tone chimes, but there is no video Reseat video card. (Make sure video card is fully inserted in connector and end of card is secured by the connector latch.) Reset PRAM (restart computer while holding down Command-Option-P-R keys until second boot tone chimes) Replace video card Reset logic board. Refer to “Resetting the PMU on the Logic Board” in this chapter. Replace logic board Resetting the PMU on the Logic Board The PMU (Power Management Unit) is a microcontroller chip that controls all power functions for this computer. The PMU is a computer within a computer. 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: Be very careful when handling the logic board. The PMU is very sensitive and touching the circuitry on the logic board can cause the PMU to crash. If the PMU crashes and is not reset, the battery life goes from about five years to about two days. Note: For the location of the PMU reset button, see “Logic Board Diagram” in the Views chapter. Many system problems can be resolved by resetting the PMU chip. When you have a computer that fails to power up, follow this procedure before replacing any modules: 1. Disconnect the power cord and check the battery in the battery holder. The battery should read 3.3 to 3.7 volts. If the battery is bad, replace it, wait ten seconds, and then proceed to step 2. If the battery is good, go directly to step 2. Press the PMU reset button once and then proceed to step 3. Do not press the PMU reset button a second time because it could crash the PMU chip. Wait ten seconds before connecting the power cord and powering on the computer. If the computer does not power on, there is something else wrong with it; refer to the “Startup Failures” section of “Symptom Charts” in this chapter. Quote Link to comment Share on other sites More sharing options...
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