VAXstation/MicroVAX 2000 CPU/FPU overheating? - test-drb@ccmp.vtda.org

25 Feb 2008

...

Subject: VAXstation/MicroVAX 2000 CPU/FPU overheating?
   From: "Dave Dunfield" <dave06a at dunfield.com>
   Date: Sun, 24 Feb 2008 22:50:56 -0500
     To: cctalk at classiccmp.org

Hi Guys,

I've just acquired a VAXstation 2000 (thanks Mouse!) which exhibits what appears
to be an overheating issue.

Powered up ir runs for about 10 mins or so (just sitting at the console prompt
doing things like TEST 50 to display the configuration, pressing ENTER to get
another '>>>' etc.). After about 10 mins (give or take) it fails,
sometimes
appears to reset, hangs etc.

Firt thing I noticed is that the two surface mount chips with the round heatsinks
affixed to them get *HOT* ... Hot enough that you wounldn't want to keep your finger
on either of them for very long.

I believe these are the CPU and FPU chip? - Is this normal for them to run this
hot? They don't heat up alarmingly quickly, but after a few minutes they are
hotter than I'd think normal. 
Yes, CPU and FPU.  They do get hot.

Makes sure then fan is running and there is airflow.

...
 Aside from the eventual failure, it seems to run
correctly - the self tests
(including the FPU test) pass (except for those which don't have hardware installed,
loopback connectors etc.

When I got the system, it was jam packed with cards, including the main board,
color frame buffer, double-sided memory expansion and an ethernet interface. 
A maxed out machime.

...
 During my testing, I've removed all of these except
for the main board, and am
running the system as a MicroVAX. I do have the resistor/loading card installed
as is recommended when running the system lightly loaded.

Power rails all look good - There is a 9V supply which the technial manual
describes as "for loading" which has a separate supply and return. Relative
to ground I measure about +5.6v on the supply and about -3.3 on the return,
which I'm assuming is normal (?) 
Makes sure the 5V line(s) is good and really at 5V.

...
 Anyone know where I can obtain anything resembling a
schematic? Other technical
information (I have a PDF of the technical manual, however it's mostly "system
information" from an operational point of view). Any known issues etc.? 
One of the signals from the PS is power good.  Makes sure that line isn't 
bouncing.  I think it's an orange or white lead it's been a while since Ive
been in one.

Allison

...
 Regards,
Dave

--
dave06a (at)    Dave Dunfield
dunfield (dot)  Firmware development services & tools: www.dunfield.com
com             Collector of vintage computing equipment:
                http://www.classiccmp.org/dunfield/index.html 