24 Nov
2014
24 Nov
'14
9:13 p.m.
On 2014-11-24 19:46, Jon Elson wrote:
On 11/24/2014 02:28 PM, Johnny Billquist wrote:
That it is huge and linear I know. I have actually replaced that
fricking thing in a KL10. It was no fun. It is seriously heavy, for
obvious reasons. (Although it's only the power for the memory system
that is this heavy linear thing, unless I remember wrong.)
What I wasn't aware of was that the power supply system actually
depended on/needed 3-phase power, as opposed to just, say, grabbing the
power between two phases (ie. getting 400V for Europe), or just use each
phase separately, but use all of them to reduce the load on individual
supplies.
Johnny
I wasn't aware that the KL needs 3-phase, but it might just be that
the power supplies are large enough, and complicated enough, that you
can't just rewire them.
The KL10B had an immense 3-phase transformer, star rectifier and capacitor
bank, which produced about 12 V DC. This was fed to a massive linear
regulator
on a huge round heat sink. Compuserve ran a LOT of KL10B's, and
designed their
own switching power supplies to save power and air conditioning costs.
They never
got DEC to pick up on that, so had to retrofit all the machines as they
came in.