sanders.parc@xerox.com (12/12/90)
Todays Macintosh support headache: Mac IIfx, System 6.05, 120 Mb Seagate HD, Microtek color scanner, 3 foot SCSI cable, black (IIfx) terminator between cable & scanner. Suddenly, Mac has trouble booting from hard disk. Starts to boot, get error tones, Sad Mac, codes 0000000F 00007FFF. Reformat HD many times. Can't re-install system software from locked Apple floppies. Can boot from floppies and use HD. Spend many hours trying to figure out what's wrong. Give up, send Mac out to Apple dealer. Dealer says: nothing wrong. Bring Mac back, hook everything up, same troubles. Get dealer tech on-site ($$$). Spends hours trying many things. Won't boot from new HD, etc. Brainstorm: whats different between office and dealer? No scanner at dealer. Trying turning scanner off or on - same problem. Finally unplug SCSI cable at Mac end - sudden success. Suspect SCSI address conflict. (Try to avoid changing the SCSI address on a Microtek color scanner - 15 minute operation!) Anyway, that did not solve problem. Called Microtek 800 number. Oops, sales, not tech support. However, they must have heard this problem before. They say: remove the SCSI terminator Now, theoretically we have 2 SCSI devices and only one (Mac internal) terminator. Heresy! But we tried it, and it worked. Don't try this at home, kids. Unterminated SCSI chains on other Macs I've known (and sworn at) have scrambled the internal HD. Morals: SCSI is a *very* dark art. Even simple setups ain't so simple. -- Rex
russotto@eng.umd.edu (Matthew T. Russotto) (12/13/90)
In article <14862@arisia.Xerox.COM> sanders.parc@xerox.com writes: >Todays Macintosh support headache: > >Mac IIfx, System 6.05, 120 Mb Seagate HD, Microtek color scanner, > 3 foot SCSI cable, black (IIfx) terminator between cable & scanner. > >Suddenly, Mac has trouble booting from hard disk. Starts to boot, >get error tones, Sad Mac, codes 0000000F 00007FFF. Love to know what that one means... not in any of my lists. >Brainstorm: whats different between office and dealer? No scanner at >dealer. Trying turning scanner off or on - same problem. Finally >unplug SCSI cable at Mac end - sudden success. > >Suspect SCSI address conflict. (Try to avoid changing the SCSI >address on a Microtek color scanner - 15 minute operation!) Anyway, >that did not solve problem. > >Called Microtek 800 number. Oops, sales, not tech support. However, >they must have heard this problem before. They say: > > remove the SCSI terminator > >Now, theoretically we have 2 SCSI devices and only one (Mac internal) >terminator. Heresy! But we tried it, and it worked. Sounds like the scanner is internally terminated. That is bad. Also, most Seagate drives come internally terminated-- three to four terminators is also bad. I guess I'm blessed-- I've connected my system with from anywhere from 1 (mac only) to 3 (Mac, Imprimis, external) SCSI terminators, and EVERY CONFIGURATION has worked. Wanna trade my Mac II for your IIfx :-). -- Matthew T. Russotto russotto@eng.umd.edu russotto@wam.umd.edu .sig under construction, like the rest of this campus.
ra@world.std.com (Chetty Ramanathan) (12/13/90)
>Called Microtek 800 number. Oops, sales, not tech support. However, >they must have heard this problem before. They say: > > remove the SCSI terminator > >Now, theoretically we have 2 SCSI devices and only one (Mac internal) >terminator. Heresy! But we tried it, and it worked. > >Don't try this at home, kids. Unterminated SCSI chains on other >Macs I've known (and sworn at) have scrambled the internal HD. The Microtek scanner is probably internally terminated. I have a similar setup IIfx, Internal HD, External HD, CD ROM, TapeBackup & Microtek scanner (SCSI port is a separate box) . I use the black terminator to terminate my chain and I've have not had any problems booting. -- -ra ------------------------------------------------------------------------------- C.Ramanathan, Software Tool & Die | ra@world.std.com 1330 Beacon St, Brookline, MA 02146,(617)739-0202 |{xylogics,uunet}world!ra
macman@wpi.WPI.EDU (Chris Silverberg) (12/13/90)
In article <14862@arisia.Xerox.COM> sanders.parc@xerox.com writes: >Brainstorm: whats different between office and dealer? No scanner at >dealer. Trying turning scanner off or on - same problem. Finally >unplug SCSI cable at Mac end - sudden success. >Called Microtek 800 number. Oops, sales, not tech support. However, >they must have heard this problem before. They say: > > remove the SCSI terminator > >Now, theoretically we have 2 SCSI devices and only one (Mac internal) >terminator. Heresy! But we tried it, and it worked. There are a couple things i've learned aobut scsi chains.... 1) Always put the scanner last 2) Scanners don't always have to be terminated. Is there a possibility that the scanner is already internally terminated? >Morals: > SCSI is a *very* dark art. Even simple setups ain't so simple. Agreed. =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Chris Silverberg INTERNET: macman@wpi.wpi.edu Worcester Polytechnic Institute Main Street USA 508-832-7725 (sysop) America Online: Silverberg WMUG BBS 508-832-5844 (sysop) "Ask me about TeleFinder... A Macintosh BBS with a Macintosh interface"
kaufman@Neon.Stanford.EDU (Marc T. Kaufman) (12/13/90)
In article <1990Dec12.161846.6240@eng.umd.edu> russotto@eng.umd.edu (Matthew T. Russotto) writes: >In article <14862@arisia.Xerox.COM> sanders.parc@xerox.com writes: ->Todays Macintosh support headache: ->Mac IIfx, System 6.05, 120 Mb Seagate HD, Microtek color scanner, -> 3 foot SCSI cable, black (IIfx) terminator between cable & scanner. ... -> remove the SCSI terminator >Sounds like the scanner is internally terminated. That is bad. Also, >most Seagate drives come internally terminated-- three to four terminators is >also bad. I know that Apple says to remove internal terminators... but: The black terminator is just a regular 220/330 ohm terminator with additional capacitance to stabilize the +5 at the terminator, so that crosstalk between SCSI signal lines is minimized. Most internal terminators are powered locally, so that the +5 is already stable (due to the low impedence and filtering in the internal wiring). Furthermore, the internal terminators can be placed MUCH closer to the SCSI controller, thus minimizing the stub length. Does anyone know the rationale for suggesting that internal terminators be removed? Marc Kaufman (kaufman@Neon.stanford.edu)