vax thermostat?

[scw at ucla-locus]

From:  Steve Woods <cepu!scw at ucla-locus>


		We went a bit further than that in terms of monitoring
	.
	.
	.
	"overtemp" stuff on the VAX power supplies is purportedly low
	enough to avoid a fire, but high enough to fry your VAX real
	good.

I used to work on an 11/40 that got fried when the Air-conditioning
people turned off the chilled water in our wing of the building; the
machine devloped wierd flakey intermentent problems after a few months,
such as hanging for 20-30 min then continuing (the only way you could
tell [if no one was on it] was the system date/time would be *WRONG*),
DEC Field service worked on the thing for 3 weeks and they couldn't fix
it until they went and replaced **EVERY** board in the CPU.  It seems
that what happened was: each board had at least 2 chips that got
moved out to the end of their life span by being cooked.


Moral: it is a *****VERY***** good idea to have a thermal shutoff
switch/circut in you power supply.