jjs@PRC.Unisys.COM (James Solderitsch) (05/09/91)
Monday:
I just got a new mac IIsi -- very neat --
much fun Monday night -- never used a color mac before -- played with the
microphone.
I bought the low-end 3mb + 40 meg HD to save money up front so I could
upgrade later.
Tuesday:
Well, I went and installed 4 1-meg 100ns ram (these are
a bit funny: only 2 chips on the simm card, but I was assured
they are OK) and booted the machine: sure enough now I had 5 megs.
I then installed my newly acquired nubus adapter card to get the
services of the FPU. The installation was smooth but on hitting the
power-on key on the keyboard, the machine would start to come up but
shut itself down a split-second later. Uh-Oh, says I -- better check
the installation. Took out the nubus adapter, powered up the machine
and voila -- up comes the desktop still showing its 5 megs. Machine off.
Went through the install of the nubus adapter again --
everything as it should be. Tried to power on -- same result: system
starts to come up for a split second, then shuts itself down -- no chimes,
no disk activity, just a split second of fan whirr. This time
I am more persistent -- check all cables, hit the power-on key several
times -- same result ... UNTIL, hit the power-on key -- NOTHING HAPPENS.
No flicker of activity, nada.
A big Uh-Oh. Take out the nubus card, and try to power-on again -- STILL
NOTHING.
Wednesday:
And that's where I sit today -- a very unhappy camper. Put back in the
original 512K simms, still nothing -- very dead IIsi.
So it went back to the dealer this morning -- preliminary diagnosis: bad
power supply. No other 3-40 si's in stock so I must wait for the next
delivery.
Some questions:
0. What was the machine doing when it would shut itself down? -- in
retrospect, it seems like it was protecting itself from some
kind of short or overload.
1. Guesses as to what went wrong: bad nubus adapter? bad motherboard?
too much load on the weak si power supply? (extra memory plus the
nubus), bad karma??
2. Is it really the power supply? I didn't see a fuse, is there a
servicible fuse? (The dealer had no IIsi power supplies either).
3. Presuming, I get a new or repaired machine, what should I do? I did
take the nubus card back (not the same dealer that sold me the
machine as they were out-of-stock) and got another one. These things
are supposed to be user-installable. Should I be wary of installing
it?
4. Could it be the memory in combination with the nubus adaptor? The
memory seemed to work fine when the nubus card was out.
My tentative plan is to try the nubus card with the original IIsi memory
configuration. If that works, I will then install the memory and the
nubus card and see. If things are fine at that point, I'll breathe a heavy
sigh of relief; if not, I will blame the memory I guess.
Should I be wary of adding a 105 meg low-profile drive too? That was going to
be the next upgrade.
Thanks for listening -- I feel better now.
Back to the Mac Plus for the time-being :-(
Jim Solderitsch
jjs@prc.unisys.comamanda@visix.com (Amanda Walker) (05/09/91)
In article <17544@burdvax.PRC.Unisys.COM> jjs@PRC.Unisys.COM (James Solderitsch) writes: 0. What was the machine doing when it would shut itself down? -- in retrospect, it seems like it was protecting itself from some kind of short or overload. Exactly. If the switching frequency of the power supply drops below a certain level (which would be caused by too heavy of a power draw), the power supply will shut down. I believe there is also a fuse, just in case it doesn't shut down fast enough. 1. Guesses as to what went wrong: bad nubus adapter? bad motherboard? Sounds to me like a short circuit in the NuBus adapter or connector. Just to reassure you, my IIsi has exactly the configuration you are trying to have (4MB of 3rd party memory and a NuBus adapter) and is working just fine :). If the same thing happens with a new NuBus adapter, I'd suspect the expansion connector on the motherboard. Should I be wary of adding a 105 meg low-profile drive too? That was going to be the next upgrade. The low-power Conner one should be OK, but I'd check the power requirements of anything else, especially if you plan to put a NuBus board in (as opposed to just using the adapter for its 68882). -- Amanda Walker amanda@visix.com Visix Software Inc. ...!uunet!visix!amanda -- X Windows: Putting new limits on productivity.