I will state this: do not buy any other parts for the machine until you've
swapped or replaced ram. reason being, it took me to replacing a
motherboard, power supply, floppy drive, and hard drive in a Mac SE, and
several days of wasted time, just to one day discover that I had bad RAM in
my machine, and that was causing the floppy to act erratic, the hard drive
not to detect in hd setup, the computer would stall during OS install. sad
macs, from what i've seen, half the time are ram issues.
On Thu, Jun 18, 2009 at 10:46 AM, Brian Lanning <brianlanning at gmail.com>wrote:
On Thu, Jun 18, 2009 at 10:36 AM, Jeff Walther<trag
at io.com> wrote:
I would check along the lines that Doc suggested.
Some times Apple's
"bus
failure" means a SCSI bus failure.
Make sure that the SCSI chain is properly terminated. If you're using
internal and external devices, confirm that both ends are terminated
properly and neither end is double terminated. Check the SCSI IDs being
used by all devices on the chain.
Go ahead and just pull the SIMMs on the motherboard. There's 4 MB on the
logic board and that should be enough to boot from, or if it gets that
far, you'll get a message about lack of memory, which is further than
you're getting now. If that happens, hold down the shift key during boot
to not load extensions. That will often save enough memory to allow
booting in 4 MB.
I don't remember the beginning of this thread, but isn't there a
suspicion
that the internal hard drive is malfunctioning?
Disconnect the internal
hard drive completely, and only connect the CD-ROM drive. That will
simplify your SCSI chain, and eliminate electronic babbling from the hard
drive as a possibility.
So, basically, pull the RAM and all SCSI devices other than the CDROM,
make sure the CD-ROM drive is terminated and set to some ID other than 7
(SCSI ID 3 is traditional for CD-ROMs in a Mac) and try that. Also
double check the cable you're using and try a different one if the first
does not work.
Once you get a successful boot, you can try adding things back in.
Thanks, I'll give it a shot. I'm not sure about the internal
termination situation. This is just a jumper on the hard drive,
right? I think the 3.5" half height drives didn't use resistor packs.
I know there's no separate terminator on the ribbon cable inside.
I'll swap out the cable and terminator.
As far as I know, the hard drive is ok.
I ordered another OS cd which should be here shortly. This one is a
new one so it shouldn't be suspect.
I supposed it's possible that the cdrom drive could be bad. I ordered
it used from ebay. It's been behaving exactly as expected though so I
believe it's ok.
brian