[aix thinkpad] anyone still out there?

[Trevor Cordes]

On 2018-04-18 Cameron Kaiser wrote:
> 
> I just want to find the fuse to begin with. If nothing else I can
> bypass it and restore the original hard disk, since I know that was
> within spec. The 850 HMM implies it's a SCSI circuit breaker, but if
> it is on the 800 as well, it certainly is not resetting
> automatically. Until that's done it won't boot from *any* SCSI device.

Welcome to the list Cameron!

If it's a fuse, it can be quite small and surface-mounted.  It can look
very similar to a SMT resistor.  Google "surface mount fuse" and click
Images to see some examples.  You should be able to tell fuses from
resistors by the fact that there should be an order of magnitude less
of them on the board.  You can lookup their codes online if you can
read them with a magnifying glass (be sure not to smudge the print
off!).

SMT repair is a bit tricky but doable at home, or find a local pro.

If it's a breaker, I have no idea what it would look like!  Perhaps
it's not really a single circuit breaker but some sort of board logic.
Perhaps resetting the whole CMOS/BIOS/whatever if possible might
"clear" it back into working.  But that's pure speculation.

> I found a couple likely suspects, but they were closed and conducting
> power, so I don't think they're the cause.

While still on-board, testing a fuse can give strange results.  There
may be power leaks and circuit cycles that will make a fuse appear to
be ok when it is not.  The only way to be sure is remove it completely.

Any fuses on the board should be standard ones you can buy replacements
for at places like digikey.

> > I don't even have my TP860 anymore.  I doubt many people do, since
> > the highest version of AIX it can run is 4.1.5 (using the internal
> > graphics card) and 4.2.1 (with a serial terminal attached).  

I think most people still listening are interested for historical /
curiosity reasons.  The PowerSeries still represents a pivotal point in
UNIX hardware development.

Now, a better question would be: are these boxes immune to Spectre? :-)