People with capacitor problems may be interested in this article in
The New York Times. Link provided: http://www.nytimes.com/2010/06/29/
technology/29dell.html?pagewanted=1&ref=general&src=me
On Jun 29, 2010, at 12:47 PM, Jim Scott wrote:
On Jun 26, 2010, at 3:16 PM, Elliott Price wrote:
I inherited a G5, 20" iMac. It had bulging capacitors, and upon
power on, it worked, but had spasmatic video artifacting. After
replacing some, then all the capacitors, the problem still
persisted, although it was much better.
Then, I got hold of a spare power supply that was a working pull,
and it works almost perfectly; but the video artifacts show up
occasionally while booting when it's still on the grey Apple
loading screen. While in Target Disk Mode, the artifacting is
HORRIBLE. Once it boots, however, it runs fine, and ran for almost
two days straight with no problems.
So my question is, does anyone know why this is still happening?
Should we try getting a new power supply?
I'm going to use it as it is, but it irks me to know that it could
fail anytime... hmm...
Any isights would be appreciated!
I also know it's not the RAM, HD or whatever. It's definitely
related to either the caps on the motherboard, or the power supply.
It's probably the quality of the resolder job. I've got a similar
situation with a 20-inch pre-ALS G5 iMac. I replaced the caps in
both the power supply and on the logic board. For a few days it ran
OK, then started throwing random kernel panics, triple beeps/
flashes on startup, weird intermittent artifacts. Then it ran OK
for a couple of days, then started doing stuff again. I could
induce artifacts by simply gripping the case tightly, so that led
me to remove the logic board and double-check all my caps' solder
joints. I found several that showed just the slightest bit of
movement on one or both legs when I wiggled the can. So I
resoldered those caps, and all was well for a couple of months,
then it started again. I suspected RAM (2 1 GB sticks), and
determined which stick worked in which slot. Then I resoldered.
This time I removed all the logic board caps, cleaned up as best I
could, and resoldered. My theory is that because I was using a
different solder than the original lead-free solder Apple used, the
bond between solders wasn't good and tended to loosen with heat/
cool cycles as the iMac was used. The resoldering seemed to work. I
used the bejeebers out of that iMac for a week or so this past
March. Some days it ran as a jukebox; others I used it to watch DVD
movies. I ran endless ASD Open Firmware and OS loops. I ran Apple
Hardware Tests, AppleJack and Memtest until I couldn't stand the
full-throttle fan noise any more. I thrashed the hard drive with
Drive Genius 3 tests. Verified the PRAM battery was 3+ volts.
Swapped out the optical drive with another known-good one. Ran it
with just the mouse and keyboard. Nada. Nary an artifact or kernel
panic or RAM beep/flash. I set it aside during April and May as my
workbench filled with a constant stream of Macs.
I brought it back to my workbench and plugged it in a week or so
ago. It immediately chimed (it's always chimed), then started with
the three beeps/flashes again. I removed the original suspect RAM
stick and it booted and ran flawlessly. I put both RAM sticks in an
eMac and ran Memtest for a whole night. Not a problem. Put them
back in their original slots, and beep, beep, beep. Rats. Removed
the stick from the suspect slot, and it ran OK.
So don't feel like the Lone Ranger. It could be we've got one or
more weak solder joints lurking. It could be that the logic boards
suffered some internal damage before we replaced the caps. Or it
could be -- and this is my current thesis -- that PG&E is sending
voodoo signals to G5 iMacs, and only G5 iMacs, in neighborhoods
where Russian spies have been living undetected.
-- Jim Scott
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