At 17:07 -0500 12/12/2005, Alan Roberts wrote:
On Dec 12, 2005, at 2:09 PM, Jeff Walther wrote:
If the other excellent suggestions you have received do not solve the
problem, it may be that your power supply has expired from old age.
Jeff Walther
Very good point. That's probably the simplest thing to test as well. Turn the
computer on and listen for the fans. If you're getting any power those will
always come on, even if nothing else works. If no fans, not even the power
supply's internal fan comes on then power supply is dead; if the
fans do start
running, then go ahead and check everything else.
While non-running fans does mean that the PS is bad, unfortunately
running fans do not mean that a power supply is good. It means that
some voltage is appearing on the 12V supply lines. If the hard
drives are spinning up then the 12V supply is somewhere in the
neighborhood of 12V, but that still doesn't mean that the power
supply is good. The 5V and/or 3.3V lines can be bad even if the 12V
is more or less working. The motherboard and CPU card will not
start up correctly without good 5V and 3.3V, so spinning fans and
hard drives with no start up chime is a possible symptom of a bad
power supply.
As far as I can tell, a PPC604/150 (no 'E') card will start up an
S900 even if the 3.3V is bad or missing. At least it will chime. It
really shouldn't output video as the PCI bus clock generator runs on
3.3V, but I think I've seen video without 3.3V connected. so a bit of
weirdness no one is ever likely to care about. :-)
Anyway, if one has a really old CPU card (150 MHz or slower) and the
machine starts up with that, then the 5V is probably good, but the
3.3V could still be bad.
BTW, if anyone is throwing away a bad PS, I would appreciate the
favor of snipping off the leads and mailing them to me. I would, of
course, pay postage. With the leads off of bad PSs I can build ATX
to S900 adapters fairly cheaply.
Jeff Walther
--
SuperMacs is sponsored by <http://lowendmac.com/> and...
Small Dog Electronics http://www.smalldog.com | Refurbished Drives |
Service & Replacement Parts [EMAIL PROTECTED] | & CDRWs on Sale! |
Support Low End Mac <http://lowendmac.com/lists/support.html>
SuperMacs list info: <http://lowendmac.com/supermacs/list.shtml>
--> AOL users, remove "mailto:";
Send list messages to: <mailto:supermacs@mail.maclaunch.com>
To unsubscribe, email: <mailto:[EMAIL PROTECTED]>
For digest mode, email: <mailto:[EMAIL PROTECTED]>
Subscription questions: <mailto:[EMAIL PROTECTED]>
Archive: <http://www.mail-archive.com/supermacs%40mail.maclaunch.com/>
---------------------------------------------------------------
iPod Accessories for Less
at 1-800-iPOD.COM
Fast Delivery, Low Price, Good Deal
www.1800ipod.com
---------------------------------------------------------------
