schoschie
07-30-2008, 06:25 AM
Greetings!
I am experiencing a bizarre hardware problem on my 4.5 year old PowerBook G4 (15" aluminum, 1.25 GHz, FW800). It has occurred twice so far, the first time a couple of weeks ago, the last time today. Since it hasn't happened earlier, I assume it to be related to mechanical/electronic "wear and tear". I have no idea what causes this exactly and what to do about it, so I'm posting here in the hope that someone may recognize the issue and can offer some selp.
The problem starts with a soft hissing/whistling/crackling noise from inside the machine. I can't pinpoint it exactly, but it appears to come from either the power supply board on the left of the keyboard (next to the dc-in) or right from the center of the mainboard (below the keyboard). After some time (depending on system load), the noise gradually gets more prominent until finally the screen goes black after a few seconds of displaying some odd bitmap patterns that look like an interlaced or "broken" version of the normal display. I then force-power off the mac since I can't see anything anyway.
(The screen seems to be just fine, as there are no problems at all before it breaks down.)
If I then let the machine "cool down" for some time and then power it up again, it boots up normally, but the hissing is still there, and I expect it to break down again if I place it under load for some time.
The hissing/whistling appears to "echo" inputs from the keyboard and mouse, i.e. I can cause it to "whistle" rhythmically when pressing keys or using the scroll wheel.
I suspect the issue is provoked by thermal strain, i.e. when the machine has been running under high load for some time, and/or high ambient temperature (we had 32 °C here yesterday).
When I remove the power supply jack (then running on battery), the hissing/whistling goes away, so it appears to be related to the power supply. [On a side note, my battery is very old (it lasts for maybe 30 minutes when full), and it seems now that it's not getting properly recharged all the time: when the machine was off, the illuminated ring around the power-in jack was green, meaning that the battery was full (no longer being charged), but when I checked the battery's load status on the battery itself, it only showed two of four green lights.]
When the machine first broke down like this a couple of weeks ago, I opened it up to check for visible damage (I was suspecting to see a burst capacitor or something), but everything appeared fine, and after re-assembly it worked without any problems until yesterday.
If this sounds familiar to anyone, I would greatly appreciate any help.
Of course, the machine is really very old now, and sending it in for repair would likely exceed its value. Even a new battery would be too much of an investment now (if that would help at all)…
I am experiencing a bizarre hardware problem on my 4.5 year old PowerBook G4 (15" aluminum, 1.25 GHz, FW800). It has occurred twice so far, the first time a couple of weeks ago, the last time today. Since it hasn't happened earlier, I assume it to be related to mechanical/electronic "wear and tear". I have no idea what causes this exactly and what to do about it, so I'm posting here in the hope that someone may recognize the issue and can offer some selp.
The problem starts with a soft hissing/whistling/crackling noise from inside the machine. I can't pinpoint it exactly, but it appears to come from either the power supply board on the left of the keyboard (next to the dc-in) or right from the center of the mainboard (below the keyboard). After some time (depending on system load), the noise gradually gets more prominent until finally the screen goes black after a few seconds of displaying some odd bitmap patterns that look like an interlaced or "broken" version of the normal display. I then force-power off the mac since I can't see anything anyway.
(The screen seems to be just fine, as there are no problems at all before it breaks down.)
If I then let the machine "cool down" for some time and then power it up again, it boots up normally, but the hissing is still there, and I expect it to break down again if I place it under load for some time.
The hissing/whistling appears to "echo" inputs from the keyboard and mouse, i.e. I can cause it to "whistle" rhythmically when pressing keys or using the scroll wheel.
I suspect the issue is provoked by thermal strain, i.e. when the machine has been running under high load for some time, and/or high ambient temperature (we had 32 °C here yesterday).
When I remove the power supply jack (then running on battery), the hissing/whistling goes away, so it appears to be related to the power supply. [On a side note, my battery is very old (it lasts for maybe 30 minutes when full), and it seems now that it's not getting properly recharged all the time: when the machine was off, the illuminated ring around the power-in jack was green, meaning that the battery was full (no longer being charged), but when I checked the battery's load status on the battery itself, it only showed two of four green lights.]
When the machine first broke down like this a couple of weeks ago, I opened it up to check for visible damage (I was suspecting to see a burst capacitor or something), but everything appeared fine, and after re-assembly it worked without any problems until yesterday.
If this sounds familiar to anyone, I would greatly appreciate any help.
Of course, the machine is really very old now, and sending it in for repair would likely exceed its value. Even a new battery would be too much of an investment now (if that would help at all)…