10 Mar
2016
10 Mar
'16
8:50 a.m.
On Thu, 10 Mar 2016 14:23:34 +0100, Peter Coghlan
<cctalk at beyondthepale.ie> wrote:
Hi Peter,
I've already reworked that pin, but to no avail. :^(
I've converted the pic to grayscale for better contrast and highlighted
the pin in red:
https://www.dropbox.com/s/ss76hldqxziazyc/ka-675-1.png?dl=0
For comparison, here's a thermograph of the 2nd KA-675 with the dead DSSI
controller:
https://www.dropbox.com/s/8twvrytrr60mrb9/ka-675-2.jpg?dl=0
The artefact doesn't show up on the 2nd board. Might be a long shot tho.
I'm not sure a chip failure would even show here. This was more of a lame
experiment, since we have the thermal tracer in the lab anyway (and the
pix look cool).
--GT
--
"END OF LINE" [MCP, 1982]
"... nowhere in the standards is it specified that 'programs that use a
lot of memory may randomly crash at any time for no apparent reason'"
[Stackoverflow forum, 2012]
FWIW, here's a thermography (hope the link works) of the B-cache
section of the KA-675 after being powered up for ca. 30 mins:
https://www.dropbox.com/s/2nsx1dfngp1jfq5/TH710065.BMP?dl=0
Note that the rightmost chip just below the CPU heatsink has a pin
that's ca. 2 degrees warmer than the others. I don't know if that says
anything, but it *is* reproducible. Maybe I should start with that one.
I can't really make it out on the image but if it is just one pin that is
hot, maybe there is nothing more complicated wrong than a bad solder
joint
at that pin, particularly if it is a power or ground pin. 
