NOTE: This is a bit general, and I might yet find the answers I'm
looking for in the archives. Feel free to ignore me if the topic has
already been covered exhaustively there.
Yes, they are, but they are fair questions.
Questions:
1. How specific is the power supply to a certain Power Mac G4 or
indeed to any Apple desktop computer made since?
VERY specific, mechanically AND electrically.
The PSUs for Power Mac G4s, at least those up to the Quicksilvers, are,
for the most part, a generic 300+ watt PSU, WITH THE FOLLOWING
DIFFERENCES:
1) the external fasteners are M3.5-0.6, which is Apple's internal standard
for a 6-32 UNC-sized fastener; Apple adopted the M3.5-0.6 fastener for
all its products which required a 6-32 UNC-sized fastener with the very
first Macintosh in 1984; however, the metric countries decided to make
this size archaic very shortly after Apple's adoption, also in 1984,
thereby making Apple perhaps the ONLY user of this fastener; not
withstanding, Apple continues to favor the M3.5-0.6 fastener as there is
no metric fastener with the same shear strength between the standard
M3-0.5 and the M4-0.7.
2) the external connectors are Apple-standard, and vary from
model-to-model, with 20 pin, 22 pin and 24 pin external connections, among
other differences.
3) some models also provide monitor power.
2. Is finding a replacement a matter of very specific model numbers
(I found a lot of replacements online quickly, ranging in price from
$60 to $180, but had no idea how trustworthy any of them might be and
remained iffy on whether the removal and reinstallation was work I
should undertake myself) or looking for certain specs?
The usual suspect Mac parts suppliers should be able to fix you up,
using a good PSU harvested from a Mac with other problems.
3. Before even considering replacement, is there something a dummy
can do to look at and into the power supply and evaluate the
situation, something as simple as oh, it's the fuse or oh, that
there cable has come loose?
There IS a fuse, but it is in the 325 volt converter section, and is
intended to protect the off-the-line section of the PSU from catastrophic
failure.
If the PSU's fuse is indeed blown, there is almost nothing which can be
done to resurrect the PSU, save an expensive component lever repair.
Besides which, that 325 volts is enough to kill you!
4. Is there such a thing as a normal or typical lifespan for a power
supply?
The PSU should last the lifetime of the machine.
Certainly, it should last the economic lifetime of the machine, which has
been over for G-series Macs for a long time now.
I get the impression that replacing a power supply isn't that big a
deal. Maybe something I could figure out myself if I had to. But
knowing everything about what to look for in a replacement isn't
something I can figure out myself. I'd like to forearm myself with
some knowledge. This new Sawtooth is older than what I traded for
it, after all, and the power supply might be as well.
It IS possible to use a generic PSU of about 300+ watts with the following
changes, which are probably WAY beyond most end-users:
1) change the 6-32-UNC fasteners to M3.5-0.6 by the simple expedient of
running an M3.5-0.6 taper tap through the 6-32 UNC holes; the basic
diameters of the two fasteners are nearly identical, so this expedient
works in 99.44 percent of the cases; or, you can acquire new 6-32 UNC
fasteners, but they probably won't be satin-finished stainless steel, like
the Apple fasteners.
2) completely disassemble the new PSU; remove its internal PCB; remove its
external cables by unsoldering them; harvest the external cables from the
failed Apple PSU and connect these to the corresponding points within the
new PSU by soldering them; reassemble the new PSU.
3) test, and pray that you didn't make even one mistake when connecting
the donor cables.
--
You received this message because you are a member of G-Group, a group for
those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs.
The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette
guide is at http://www.lowendmac.com/lists/netiquette.shtml
To post to this group, send email to g3-5-list@googlegroups.com
For more options, visit this group at http://groups.google.com/group/g3-5-list
