28 May 2005

Today's Link...

...is one from before...

http://topicdrift.blogspot.com

...repeated as the last couple of posts have been brilliant, IMO. I'd offer to bear her children, were it for a certain biological escape clause :-)

3 comments:

Anonymous said...

I didn't see a better place to put this but you have some errors on one of your pages regarding bad capacitors, the second picture of the inside of a power supply you note failure of the capacitors, these capacitors look fine and they just have hot glue on them to connect them together or to other components to improve vibration tolerance and to prevent rubbing and shorting to other components, the last picture of a video card also has no defect that I can see, I only see some black epoxy on the sides of the inductors labeled 6R8 and 2R2, thought you might want to know since you are supposed to be a tech guy!

Chris Quirke said...

Interesting assertions... let's have a look at that http://cquirke.mvps.org/badcaps.htm page (I assume that's the one you mean)... ah yes.

You're looking at the wrong thing, where the PSU caps are concerned. The badness isn't the glue, but the bulging of the middle of the three caps; the other two caps in the detail photo are OK.

Same thing on the SVGA card; the top two caps are OK, but the bottom one has started to bulge.

Eventually these bulging caps may vent goo and be obviously bad, but the bulge is enough to know that gas release has started. Often mobos that won't POST have this bulging, with no venting, and work when the bulging caps are replaced.

You raise a good point about glue, though, as this can look like base leakage, especially on the big caps inside PSUs. I've been seeing that sign since before the capacitor crisis, on working PSUs I was dusting out, and assumed it to be innocuous. Now that I'm aware of bad caps, I wonder whether all the brown the goo I see at the base of these big caps is glue, or whether some are actual leakage; generally, unless I see something else, I assume it's glue.

I've only seen rampany electrolyte leakage once, and that was when a PSU saw 220V when it was set to 115V. The bottom of the case was sopping with light blue fluid,quite different from the denatured brown dried gunge that you see when a cap has gassed, bulged, vented, and baked.

In summary: Look for bulging, don't wait for venting.

Chris Quirke said...

Interesting recent comments, in that they appear to be from spambots (or spam humans), and that they are to such an old post.

Presumably it's the generic blog item subject line that attracts them, or that there are already comments to this article, and thus presumably readers?