SUMMARY: sparc1+ hanging

From: Upkar Singh Kohli (
Date: Thu Dec 10 1992 - 18:09:15 CST

Original question:
> I had an external harddrive go down recently on a sparc1+. After I
> removed the disk from the machine, the sun won't even start the
> "testing" procedure... it just hangs, and accepts nothing from the
> keyboard. I powercycled the machine few times with no effect.
> The external disk was a Micropolis in a shoebox. The sparc1+ has an
> internal disk with OS4.1.1. The testing goes through ok if I connect
> the external drive, but I don't want to do that!

Quick check from one expert:
   switch the ethernet fuse with the scsi fuse and see if the system boots

Answer from the experts:
   The SCSI fuse was blown.
   Part: Littlefuse 273002 (2A Microfuse subminiature 125V).

Analysis from some experts:
   - It works with the external drive attached because the drive is supplying
   terminator power back to the internal terminators in the SPARCstation.

   - To verify that it is the fuse, supply power to an external terminator from
   an external device (eg. set the appropriate jumper on your disk). The machine
   should boot up fine.

   - Take the cover off and check both internal fuses with an ohmmeter.

   I got the fuse from a local electronics store ($2.10 for a pack of 2).
   But one response pointed to:
     Littelfuse (708) 824 1188, street address:
     800E, North west Highway, Des Plaines, Ill.
   One of many responses:
     open up the machine, look on the motherboard close(ish) to the SCSI plug,
     for a SCSI fuse (it looks like a small rod, 3mm diameter, one end
     clear, the other end black, with two leads coming out of the black
     end. Ground yourself, pull it out. Then go find/buy/borrow/steal
     a replacement. I suggest if you can, get a couple of spare ones.

     Note that when you have a blown SCSI fuse, even L1-A won't work,
     and like you say you can't run diagnostics. Bummer.

Suggestion from the experts:
   Never unhook any device before turning it off
     (I think I did exactly that!)

Some other sugestions:
   - try terminating the SCSI port
   - motherboard might need to be replaced
   - try scsi-probe [not possible, as original question states]

Thanks to the following experts for their great responses:
"John D. Barlow" <> (Peter Gross)
Peter Samuel <>
Peter Shipley <shipley@tfs.COM>
zeke@mpl.UCSD.EDU (Rob Scott)
Wilson N G <> (Toby) (Birger A. Wathne) (Geert Jan) (Hans Baumeister)
rick%pgt1@Princeton.EDU (Rick Mott) (Russ Poffenberger)
Paul Rundans <> (LDC - Raul Silvera)
TS@CS-IND.Prime.COM (Ted Schafer)
trdlnk!mike@uunet.UU.NET (Michael Sullivan)
John DiMarco <>

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