12 Jan
2022
12 Jan
'22
3:39 p.m.
On Wed, 12 Jan 2022 at 19:30:58 +0000, Peter Coghlan via cctalk wrote:
On Wed, 12 Jan 2022 at 11:02:47 -0600 Jon Elson via
cctalk wrote:
I looked around some more with the magnifying glass and found the tiniest
crack in the body of one of the smaller orange components, the vertical one
in the middle of the picture. I desoldered it and measured it. It was
9.73uF and had 35.7 kOhms leakage (the 47uF one had no measurable leakage).
It is not one of the three I suspected initially and it has 12V across it
in operation, possibly associated with the nearby AUI connector. I presume
it is a 10uF unit and despite having released some magic smoke, it seems to
be continuing to function reasonably well.
I guess failure of these sort of capacitors is probably not anything to do
with the cache failures I am getting then.
Time to get back to the power supply I think.
Regards,
Peter.
On 1/11/22 5:17 PM, Peter Coghlan via cctalk
wrote:
Thanks again Jon.
They do have spikes of solder sticking out from the positive ends
which can be seen in the picture. There are no circuit references on
the I/O board where the picture was taken. However there are markings
on the system board including little + signs at the same ends as the
solder spikes on similar capacitors on that board.
I managed to desolder one of them from the middle of the picture using
two soldering irons. I am not very good at this surface mount stuff :-(
It came out ok though. I must have got lucky and picked a good one
because it measured 47uF on the capacitance range on my multimeter.
Thanks Jon.
Here is a badly focused picture of the suspect components:
http://www.beyondthepale.ie/cctech/p1010198.jpg
WOW, I don't know what those are!? They look like big
ceramic caps to me, but if they don't have any polarity
marking, then they can't be Tantalum.? Big multilayer
ceramics are prone to cracking due to board flexing, and
that can cause catastrophic failure, too.
Jon