PDP-8/A transformer hum

[Anders Nelson]

Related question: Is there any reason, other than historical accuracy and
cost, to not replace the power supplies in vintage computers with modern
switching power supplies?

--
Anders Nelson


On Tue, Jun 9, 2020 at 10:19 AM Paul Koning via cctalk <
cctalk at classiccmp.org> wrote:

>
>
> > On Jun 9, 2020, at 2:59 AM, Josh Dersch via cctalk <
> cctalk at classiccmp.org> wrote:
> >
> > Hi all --
> >
> > I'm working on a PDP-8/A I picked up at VCF West last summer.  After a
> lot
> > of cleaning and some power supply repair it's showing signs of life (CPU
> > seems to be at least minimally functional, core memory is going to need
> > some debugging.)
> >
> > The transformer in the power supply is humming quite loudly, however, and
> > I'm curious if this is normal for the 8/A (or is typical for an 8/A of
> this
> > vintage).  I'm used to the supplies in various other DEC machines not
> being
> > exactly silent but this is a rather severe 60Hz buzz that you can clearly
> > hear over the fans when the machine is in operation.
>
> Assuming these are traditional transformers with laminated sheet iron
> cores, check if the rivets or screws holding the laminations together are
> loose.  If yes, tighten or replace the fastener.
>
>         paul
>
>