On Wed, Feb 15, 2006 at 11:51:53AM +0800, Chen Xiao Fan wrote:
 
> Check the specification of those Schottky diodes. Often they can not
> withstand high reverse voltage. I think this could well be the
> reason of failure for your diodes.

Good point, I noticed in the specs that there are two Vr's... One at
15V,  saying Tj = 100C and another one listed as Vrwm, Tj = 125C, at
5V...

So does that mean that Vr decreases to 5V when the junction temperature
is 125C?


Note that when the diodes failed the first thing I did was check how hot
they were, and they were only slightly above room temperature, a little
warm, but nothing more. That's after 30 minutes, so I don't think the
heat just hadn't reached the case or something.

> Do you have Varistors before the diode bridge? This might help as well.

No I don't. I'll look into those.

-- 
pete@petertodd.ca http://www.petertodd.ca
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist