Bad disk capacitor?

I have been working on stuff for almost 50 years and I just had my first shorted disk capacitor. (those flat brown ceramic looking
things) This was a stereo amp blowing the fuse. I fairly quickly isolated it to the power supply section and knew it wasn't a diode or the transformer. That left me with 2 big electrolytics and 4 disks. I took out the electrolytics with no joy so I decided I would just 'smoke it out". I put in a 6a slow blow and ride the glow if the element in the fuse with the power switch until I saw one of the disks changing color and figured out it was an internal bolted fault.
The numbers on these were undecipherable so I just found one in my junk box about the same physical size and went with it .
Fixed another one.,
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote in message
I have been working on stuff for almost 50 years and I just had my first shorted disk capacitor. (those flat brown ceramic looking things) This was a stereo amp blowing the fuse. I fairly quickly isolated it to the power supply section and knew it wasn't a diode or the transformer. That left me with 2 big electrolytics and 4 disks. I took out the electrolytics with no joy so I decided I would just 'smoke it out". I put in a 6a slow blow and ride the glow if the element in the fuse with the power switch until I saw one of the disks changing color and figured out it was an internal bolted fault.
The numbers on these were undecipherable so I just found one in my junk box about the same physical size and went with it .
Fixed another one.,
That disk capacitor could have been a MOV (Metal Oxide Varistor) or a thermal fuse, or just a fuse. They all look very similar. Also the fact that the part number didn't make sense would lead me to believe that it could have not been a capacitor. Look them up on the net, there are subtle differences on color, shape, how the leads come out and of course part number.
Shaun
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 9/28/2013 1:36 PM, snipped-for-privacy@aol.com wrote:

Not intending to offend you but, you replaced an unknown part with something of similar size and shape?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Yup. To the other poster, I am sure this was a capacitor, an MOV would have been closer to the line and yes I just stuck one in. It was only there to decouple high frequency stuff in the power supply I am guessing and that is not a critical application.
This thing was about a minute from being on the curb anyway. That is why I did the smoke test. I can go down to goodwill and get another "no name" amp for $5 any time I want.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@aol.com wrote:

If you still have the removed part, you can chip away the cover and see what is underneath. Titanate disks look like silvery coated disks. You might even be able to find the short and measure capacitance of an unshorted piece of the disk. A pice of MOV might also look like ceramic. You should, however be able to measure some high resistace through an undamaged piece/
--

Sam

Conservatives are against Darwinism but for natural selection.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 01 Oct 2013 16:08:07 -0700, Salmon Egg

Thanks guys I was able to track down the numbers and it is a .01ut 250v cap. I think that is what I put in there. Even a blind pig gets an acorn every once in a while ;-)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.