13 Aug
2013
13 Aug
'13
2:33 p.m.
On 8/13/2013 2:19 PM, Dave wrote:
On 13/08/2013 21:45, Robert Ollerton wrote:
This is still routinely done even today on most high end equipment. We
have software control of all power supply set points, and routinely
margin the supplies +/-5% during diagnostic testing (as well as
stressing them from 0'C to 55'C ambient in thermal chambers at the same
time).
There are no twisty knobs on the front panel but the function is there
none the less.
Don
I know on the SDS Sigma, margins were adjustable
in a step up or down
from
normal via a 3 position switch on the control panel/ This signal was
chained thru all the core memory power supplies. circa 1969 and before.
On Tue, Aug 13, 2013 at 11:06 AM, John Wilson <wilson at dbit.com> wrote:
> On Tue, Aug 13, 2013 at 06:15:41AM -0500, Chris Elmquist wrote:
>> Interesting pictures. I am curious why machines of this era often
>> have
>> a "VOLTAGE" adjustment on the front panel? Was it really neccessary
>> for an operator to adjust some voltage setting as the machine ran thus
>> requiring that adjustment to be easily accessible on the front panel?
> I dimly remember (probably from the Gordon Bell book?) that KO+crowd
> were weirdly obsessed (or maybe normally obsessed given the known
> failure
> modes of the time) with marginal testing. So they liked to crank
> things
> up to the high and low limits every so often to find parts that were
> about
> to stop working at the nominal voltages. So I think that's what
> that is...
>
> John Wilso
> D Bit
>
On the Honeywell L66 and similar (so possible the Multics Machines as
well) the engineers diagnostic software could vary the voltages on the
PSUs so it could check it worked "on Margins". A far as I remember we
did this routinely. I believe the Ferranti Pegasus from 1953? also had
adjutable supplies. This was a valve machine ...
Dave
G4UGM