Who's rewired their house for this hobby?

Johnny Billquist bqt at update.uu.se
Mon Nov 24 23:13:53 CST 2014

On 2014-11-24 19:46, Jon Elson wrote:
> On 11/24/2014 02:28 PM, Johnny Billquist wrote:
>> 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.

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 


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