Capacitors on M8722 Board

Jon Elson elson at
Sat Sep 4 10:40:31 CDT 2021

On 9/4/21 4:34 AM, Rob Jarratt via cctalk wrote:
> I have a PDP 11/24 which I hope to power up soon. The last time it had power
> I noticed a bit of a burning smell which I failed to track down. However, I
> did notice one capacitor on a memory board has a strange appearance, almost
> as if there is some corrosion under the surface, it doesn't seem to be
> bulging though, except along the top, but if it is bulging it is very bumpy.
> I have a picture of it here:
> It is marked 47uF 30V, but it is also marked 20v as can be seen in the
> picture.

Voltage is not critical, as long as it is above the supply 
on that bus.  But, that aluminum electrolytic cap certainly 
looks like it is ready to fail, possibly catastrophically.


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