Powering up a 20-year old MicroVAX II

[Tony Duell]

> 
> > If it was plugged in but not switched on and something popped, it'll be
> > the mains filter cap.  They *do* fail, and they're easy to replace.
> 
> In seeing photos of this in the process of dealing with it offlist,  it looks 

I really do wish I'd got all the information...

> exactly like that's what it was.  When I asked about the markings on the 
> failed parts I was told that they included "250V",  which is way inadequate 
> for UK mains voltages...

Not necessarily. Some mains filter capacitors used over here are rated at 
250VAC working. In other words they are designed to work on 250V (or 
less) AC mains.The DC rating is a lot higher.

There are also several 'classes' of mains filter capacitors (X2, Y2, 
etc). One of them (I forget which, but I would check before replacing 
anything) is designed so it can't fail short-circuit. That is the type to 
use between either side of the mains and the case/dafety earth. The one 
across the mains is less critical safety-wise.

-tony