16 May
2007
16 May
'07
3:24 a.m.
Hi all,
my first VAX ever - died, unfortunately. During the last months, I experienced that the
CPU just got stuck at some time, but I could not reproduce this error.
Sometimes, it froze during or directly after the initialisation procedure, or later on
after half an hour or an hour of work with VMS.
A friend of mine thought of instable voltages caused by the power supply, so I swapped it
with another one in order to check, if the supply was to blame.
But it wasn't the case. I took out all the boards and left the CPU and some memory
only, but it didn't get any better. After getting stuck, the CPU could only be reset
switching the supply off and on again.
And now, since last week, the CPU doesn't come up at all anymore. After switching on
the power supply, the seven segment display shows an "F",
nothing is printed on the terminal, and the halt-button has no function anymore (which was
always the case when it got stuck). So I guess that my VAX died...
Needless to say that these boards can't be repaired. As far as I know, no schematics
were ever published and these big chips on the board are horrible to unsolder and solder,
even
if spare ones could be obtained (supposed that one knows, where the "problem
is").
Did anybody on this list make similar experiences regarding VAXen dying that way (at
least, I'm pretty sure that she's dead) ?
Is there anything else I could check in order to save my VAX ?
Thanks for any help.
Regards,
Pierre
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16 May
16 May
6:23 a.m.
Pierre Gebhardt <cheri-post at web.de> wrote:
my first VAX ever - died, unfortunately. During the
last months, I experienced that the CPU just got stuck at some time, but I could not
reproduce this error.
Sometimes, it froze during or directly after the initialisation procedure, or later on
after half an hour or an hour of work with VMS.
A friend of mine thought of instable voltages caused by the power supply, so I swapped it
with another one in order to check, if the supply was to blame.
But it wasn't the case. I took out all the boards and left the CPU and some memory
only, but it didn't get any better. After getting stuck, the CPU could only be reset
switching the supply off and on again.
And now, since last week, the CPU doesn't come up at all anymore. After switching on
the power supply, the seven segment display shows an "F",
nothing is printed on the terminal, and the halt-button has no function anymore (which
was always the case when it got stuck). So I guess that my VAX died...
Needless to say that these boards can't be repaired. As far as I know, no schematics
were ever published and these big chips on the board are horrible to unsolder and solder,
even
if spare ones could be obtained (supposed that one knows, where the "problem
is").
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.
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.
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!
Tim.
10 a.m.
On 5/16/07, Pierre Gebhardt <cheri-post at web.de> wrote:
Hi all,
my first VAX ever - died, unfortunately. During the last months, I
experienced that the CPU just got stuck at some time, but I could not
reproduce this error.
Sometimes, it froze during or directly after the initialisation procedure,
or later on after half an hour or an hour of work with VMS.
A friend of mine thought of instable voltages caused by the power supply,
so I swapped it with another one in order to check, if the supply was to
blame.
But it wasn't the case. I took out all the boards and left the CPU and
some memory only, but it didn't get any better. After getting stuck, the CPU
could only be reset
switching the supply off and on again.
And now, since last week, the CPU doesn't come up at all anymore. After
switching on the power supply, the seven segment display shows an "F",
nothing is printed on the terminal, and the halt-button has no function
anymore (which was always the case when it got stuck). So I guess that my
VAX died...
Needless to say that these boards can't be repaired. As far as I know, no
schematics were ever published and these big chips on the board are horrible
to unsolder and solder, even
if spare ones could be obtained (supposed that one knows, where the
"problem is").
Did anybody on this list make similar experiences regarding VAXen dying
that way (at least, I'm pretty sure that she's dead) ?
Is there anything else I could check in order to save my VAX ?
My vax 3900 randomly gave me "machine check 10" errors. Finally I bought
another vax 3900 and swapped the CPU board, and the problem was fixed.
vax, 9000
Thanks for any help.
Regards,
Pierre
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5:15 p.m.
Hi all,
my first VAX ever - died, unfortunately. During the last months, I experi=
enced that the CPU just got stuck at some time, but I could not reproduce=
this error.=20
Sometimes, it froze during or directly after the initialisation procedure=
, or later on after half an hour or an hour of work with VMS.
A friend of mine thought of instable voltages caused by the power supply,=
so I swapped it with another one in order to check, if the supply was to=
blame.=20
Have you actually _measured_ the power supply voltages? Or for that
matter checked the ACLO/DCLO (Power OK) signals that I assume are
genereated by the power supply.
[...]
And now, since last week, the CPU doesn't come up
at all anymore. After s=
witching on the power supply, the seven segment display shows an "F",=20
If this is like other DEC machines (PDP11s and VAXen), all bits of the
LED output port are effectively set in hardware on a reset (giving you
the 'F'). The processor then writes other values to said port. Given that
you never get aything but the 'F', it would appear tht the processor
isn't doing anything. But that doesn't necessarily mean one of the custom
chiops has failed.
[..]
Needless to say that these boards can't be
repaired. As far as I know, no=
schematics were ever published and these big chips on the board are horr=
ible to unsolder and solder, even
if spare ones could be obtained (supposed that one knows, where the "pro=
blem is").
If it is a custom chip that's died, then (de)soldering it is the easy
part of the repair ;-)
But before you assume that, I really would check all the power supply
voltages. And amke sure the ACLO/DCLO signals aren't atuck asserted. Can
you trace out bits of the CPU board circuit to identify the clock source
and reast? If so, it'd be worth checking those next.
-tony
6272
days inactive
6272
days old
3 comments
4 participants
participants (4)
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ard＠p850ug1.demon.co.uk -
cheri-post＠web.de -
shoppa_classiccmp＠trailing-edge.com -
vax9000＠gmail.com