16 May
2007
16 May
'07
5:23 p.m.
Pierre,
since you're on web.de, i assume you are in Germany (or close...).
I'm located in Reutlingen, so: Would it help if i sent you a known
working KA660 CPU-Board to try it out?
At least you could rule out other failures this way.
Alternatively, i could "press" your CPU in my VAX 4200 to see what
happens....
Greetings
Michael (ms)
Pierre Gebhardt wrote:
Hello Tim,
--
Michael Schneider email: ms at vaxcluster.de
Germany http://www.vaxcluster.de
"Man muss nicht immer alles glauben was stimmt"
What you write is "not inconsistent"
with failing to get DCOK from the
power supplies. DCOK is a signal indicating that the power supplies
are all up and operating. The CPU refuses to even begin its self test
until DCOK is asserted.
Thanks alot for pointing out several things I forgot to mention. My VAX is housed in a
BA430 enclosure.
So there is only one power supply which provides the power to the system. Normally, when
the green
"DC OK" LED turns on, the DC voltages should be available and lie within the
necessary voltage range for the CPU
to work correctly. Now I don't know how reliable the control circuit is, regarding
the detection of voltages lying outside of
the specified range. Could it be possible that the DCOK LED lits while a voltage is not
within the required tolerance ?
BA213's (a popular cabinet for your CPU) have
two supplies and the light
has to be on on both of them. Otherwise you see exactly the symptom
you have (CPU stuck at "F").
It's not impossible for a CPU board to fail and get stuck at "F", but
in my experience, 99 times out of 100 it's because there's no DCOK on the
backplane. And 9 times out of 10 it's because the power supply is
failing. They often go flaky and are hard to start, or go flaky and
fail after getting warm, etc.
Ok, in my case, having a BA430 chassis, both tested power supplies would have the same
failure then. I tested both, and only
one fits in the chassis at a time.
On both supplies, the DCOK-LED turns on after powering up the VAX. But just to be sure,
I should measure the
voltages of the supply at the backplane.
It's also true that the power supplies need a
certain minimum load...
you may have had some boards in your backplane that had nothing except
for resistors on them to provide the minimum load. Putting those
back in won't hurt. Of course, spare KDA50 sets are just fine for
sucking up DC power too!
A total of seven boards were plugged in, so I guess that the minimum load should be
given.
Thanks alot for your precious hints, Tim !
Regards,
Pierre
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