Powering up a 20-year old MicroVAX II - test-drb@ccmp.vtda.org

23 Feb 2009

They can often go down internally without the top going.
Some have vents that end up next to the PCB.

I did four years in a high voltage test lab.  

And.....

Yes they do pop and they can explode!

Rod Smallwood

-----Original Message-----
From: cctech-bounces at classiccmp.org
[mailto:cctech-bounces at classiccmp.org] On Behalf Of Gordon JC Pearce
Sent: 23 February 2009 10:25
To: On-Topic and Off-Topic Posts
Subject: Re: Powering up a 20-year old MicroVAX II

Rod Smallwood wrote:
...
  Hi
    Sounds like capacitors. 
 Alhough it's a switcher any high voltage/high value capacitors in the 
 PSU might well need reforming.
 Quite often you will see caps with a pair if incised lines on top. 
 This makes them go pop instead of bang.
 You would not want to see a PSU where they have gone bang. 
This is the only popped electrolytic I have ever seen, in damn near 30
years of fiddling with electronic stuff:

http://www.gjcp.net/~gordonjcp/blowncap.jpg

Gordon