on 7/5/00 12:31 AM, tk97el12.technis.syh@technis.syh.fi at
tk97el12.technis.syh@technis.syh.fi wrote something like:

> Hi,
> 
> After a closer look at the components on the pwr-supply's board and
> I noticed that a capacitor had leaked, there was some brown stuff on
> the board around it ... I replaced the damaged capacitor but it had
> no effect, maybe some other components that looked affected by the
> brown stuff need replacements. The brown stuff must have been some
> kind of acid, because it seems to have "eaten" a bit of solder!

    Hmm well lets just say that washing your hands/PC boards with
electrolyte is NOT a good idea ;-) I don't recall exactly what they put in
Electrolytic caps, but it's not good to have around anywhere. I haven't
opened a DEC PS before so I wouldn't be able to help you without a
schematic.

> The potentially dangerous big capacitors on the board are well
> marked with big flash-marks. (cool detail DEC!)

    LOL

> I checked the fans by feeding them individually with 12V DC each,
> they seemed fine so I rewired power from the hdd connector; the fans
> blow now at full speed all the time.

    Better than no fans, my 5000/200 would meltdown if the fans stopped
working.
 
> About the DS's overheating sensor: I got a message on the console
> running ultrix, something like this:  "system overheating,
> shutdown recommended" I don't remember the exact words. The machine
> had been running for perhaps half an hour (without fans!)

    Well that would seem to imply that the temperature sensor in the CPU is
still working, so your fan issues are most likely still inside the power
supply with a transistor/SCR/{DIAC/TRIAC}.

> Is this warning-feature implemented in netbsd?

    I do not believe it is, albeit a very good idea to add! I know on some
very large VAXen, they had airflow sensors in the power supply, so if there
was no circulation the power supply would turn the computer off. (The kind
of VAXen that need 3 phase 400 amp service of their own) I seem to remember
one of the 9000 series I think that sucked down like 30kW (dual CPU's,
cooling blowers, multiple cab's, etc.) talk about meltdown!


    Chris