johnm@phoenix.Princeton.EDU (01/26/91)
HELP! Calling all network Mac wizards. I would be incredibly grateful if
someone out there can give me some advice on the following serious problem with
my Macintosh SE.
*** Description of the problem: ***
- I turn on the power to the computer, and hear the normal startup beep sound
for the SE.
- Immediately the screen comes up with a black-and-white checkerboard pattern.
At no time does the normal medium-gray screen appear. The checkerboard display
is composed of 1 cm by 3 cm rectangles, alternating either black or white, that
fill the entire screen.
- After about one to two seconds the happy Mac icon appears in the center of
the checkerboard screen. This icon looks exactly the same as it should under
normal startup circumstances. No numbers or other symbols accompany this icon.
- The hard drive sounds like it is spinning up as usual. Soon, however, the
drive falls silent and makes no further noise.
- The display remains locked showing only the black-and-white checkerboard
screen with the happy Mac icon in the center.
*** Background information: ***
Until recently, this Mac SE had a Quantum ProDrive 80 and 4Mb of memory. Both
the drive and RAM were moved into a Mac IIsi. The IIsi contained a Conner 40Mb
hard drive and 4 256Kb SIMMs, and these were put into the Mac SE.
All this equipment was correctly installed. The IIsi works fine. The Mac
SE now contains the hard drive and memory from the IIsi, with every device,
SIMM, and cable in its place.
Now, I have a few ideas what might be wrong here, and I'd like to see if anyone
on the net can confirm or deny, or make other suggestions.
- The SE had a resistor clipped to allow it to access the 4Mb of upgraded RAM.
(As one of the original run of SEs, this machine has a resistor rather than a
jumper that required clipping to increase RAM.) Now of course it is back to
4x256Kb SIMMs or 1Mb of RAM.
Could the clipped resistor be responsible for the bizzare startup error?
The screen seems to show up so immediately upon startup that its seems unlikely
the memory was actually being checked before the error occurs.
- The SIMMs installed in the SE are from the IIsi, so they have a rated speed
of 70ns.
Could it be that the IIsi SIMMs are too fast for the SE? I was under the
impression that you couldn't go wrong by installing faster than required SIMMs
in any machine (except that you might have to pay more for them).
This is as much as I know about this problem. I am under some time pressure to
get the Mac SE back up and running. If the problem is in the SIMMs/resistor,
then as far as I am concerned the best solution would be getting my hands on
some new 1Mb SIMMs fast.
Thanks in advance for anyone going to the trouble of helping me out.
John Mitchell johnm@phoenix.Princeton.EDU
Princeton Universityjeffe@eniac.seas.upenn.edu (George Jefferson ) (01/28/91)
: Could the clipped resistor be responsible for the bizzare startup error? :The screen seems to show up so immediately upon startup that its seems unlikely Hmm. Having the resistor in place indicates 'all 256' I always wondered if you really needed to reconect the resistor when going back to all 256's. (I am not so curious as to take my machine apart to try it..) : Could it be that the IIsi SIMMs are too fast for the SE? I was under the :impression that you couldn't go wrong by installing faster than required SIMMs :in any machine (except that you might have to pay more for them). : It could never hurt for the simms to be 'too' fast : :This is as much as I know about this problem. I am under some time pressure to :get the Mac SE back up and running. If the problem is in the SIMMs/resistor, :then as far as I am concerned the best solution would be getting my hands on :some new 1Mb SIMMs fast. : It should be no big deal to reconnect the resistor. At least when I cut mine I made sure to cut the lead right in the center so that it would be easy the re-connect. I assume that anyone who knew what they were doing would do the same. Apple dealers probably remove the resistor all together... :-)( -- -george george@mech.seas.upenn.edu
russotto@eng.umd.edu (Matthew T. Russotto) (01/28/91)
In article <5712@idunno.Princeton.EDU> johnm@phoenix.Princeton.EDU writes: >*** Description of the problem: *** > >- I turn on the power to the computer, and hear the normal startup beep sound >for the SE. > >- Immediately the screen comes up with a black-and-white checkerboard pattern. >At no time does the normal medium-gray screen appear. The checkerboard display >is composed of 1 cm by 3 cm rectangles, alternating either black or white, that >fill the entire screen. > >- The SE had a resistor clipped to allow it to access the 4Mb of upgraded RAM. >(As one of the original run of SEs, this machine has a resistor rather than a >jumper that required clipping to increase RAM.) Now of course it is back to >4x256Kb SIMMs or 1Mb of RAM. > Could the clipped resistor be responsible for the bizzare startup error? >The screen seems to show up so immediately upon startup that its seems unlikely >the memory was actually being checked before the error occurs. This is it-- the Mac thinks the screen is at one location, when it is actually at another (no, I don't know why the happy mac shows up in both locations, but it always does) -- Matthew T. Russotto russotto@eng.umd.edu russotto@wam.umd.edu .sig under construction, like the rest of this campus.