SUMMARY: Please help: IPC == "no keyboard" warning!

From: Rachel Polanskis (
Date: Mon Jul 08 1996 - 20:54:25 CDT


First a big thankyou for:

All helpful messages (mostly)

The original problem was due to my hacking my mouse cable -
which I neglected to mention was a *mechanical* Logitech Mouse.

This resulted in blowing the keyboard fuse
and subsequently my losing access to the console keyboard,
and locking me out of the machine.

A reboot showed I had no keyboard attached,
even though this was (technically) untrue...

A Sun IPC however will not boot if there is no keyboard

I could then only get the machine to boot by connecting a
Wyse terminal.

Many answers blamed the original mouse problem on my having
the mouse pad oriented incorrectly, but on a mechanical mouse
it of course makes no difference.

The mouse problem was indeed caused by a broken cable inside.
However in replacing the cable, I did not take into account the impedance
of the replacement cable - thereby blowing the keyboard fuse.

The general consensus was that I had blown this fuse - which upon receiving
a nice shiney new second hand *optical* mouse, and getting my hands
on a replacement fuse I found to be the case.

I promise on a stack of man pages never to hack my
peripheral hardware again with the power on.

It is a good thing that Sun provided a fuse for such ports as the keyboard, the SCSI
bus and the like, as it stops foolish people from sticking things in ports
that might otherwise blow the motherboard.

It turns out these fuses are hard to come by - but I have managed
to source some replacements.

Since the keyboard fuse is the same as the SCSI one (and I believe ethernet as well)
it would be wise to have a collection of these handy for future emergencies.

The fuse is easy to replace - and it looks like a little capsule.
The SCSI and Ethernet fuses are together near the side of IPC mainboard
that carries the power supply.

The keyboard fuse is located near the B serial port.

According to the Sun Hardware FAQ:

        Additional features of interest: the boot PROM is in the middle
        left edge at location U0902. The NVRAM/TOD/ID chip is nearer
        than the boot PROM, at location U0901. At the far edge, from
        left to right, are the power, floppy, speaker, and internal SCSI
        connectors. The Ethernet (F0802) and SCSI (F0801) fuses are in
        the near left corner, P/N 150-1174. (150-1974 and 150-1162
        repsectively may also work?) The keyboard fuse F0901 is by
        serial port B, P/N 150-1174 (150-1162?).

Many thanks to all who advised me of the problem.
I was quite unaware that there was a fuse for the keyboard -
although I was aware of the SCSI and ethernet ones...


Rachel Polanskis                 Kingswood, Greater Western Sydney, Australia      
                Witty comment revoked due to funding cuts

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