2 Jul
2004
2 Jul
'04
11:33 a.m.
Dan Kolb <dankolb(a)ox.compsoc.net> wrote:
I decided to power on my MicroVAX 3800, after it's
been idling for a couple of
years (unfortunately due to lack of time on my part), only to find that it's
not booting properly. The LED display on the cover/patch panel sits saying 'F'
(apparently "Waiting for CDOK"); nothing else happens. Anyone got any ideas as
to what may be wrong, or if it's fixable?
First of all, it's DCOK, not "CDOK". Second, the problem may not be in
the CPU board, it may be the PSU. E.g., it's out of tolerance and does
not assert the DCOK signal. Follow Tony's advice: check the PSU voltages
and the state of the DCOK signal before randomly swapping parts (and
certainly before rushing out to eBay to buy a new KA655 board).
MS
2 Jul
2 Jul
1:47 p.m.
--- Michael Sokolov <msokolov(a)ivan.harhan.org> wrote:
Dan Kolb <dankolb(a)ox.compsoc.net> wrote:
Agree. I have a VAX3900
<http://www.geocities.com/mscpscsi/VAX3900.html>. My
guess is that you have kind of 'minimal' system such
that all your boards are on the right half of the
backplane. Since no board is drawing power from the
leftside PSU it is unhappy. Solution is to add any
board for the left side PSU as I did. I used a M9060
load board.
vax, 3900
I decided to power on my MicroVAX 3800, after
it's
been idling for a couple of
years (unfortunately due to lack of time on my
part), only to find that it's
not booting properly. The LED display on the
cover/patch panel sits saying 'F'
(apparently "Waiting for CDOK");
nothing else
happens. Anyone got any ideas as
to what may be wrong, or if it's fixable?
First of all, it's DCOK, not "CDOK". Second, the
problem may not be in
the CPU board, it may be the PSU. E.g., it's out of
tolerance and does
not assert the DCOK signal. Follow Tony's advice: check the PSU voltages
and the state of the DCOK signal before randomly
swapping parts (and
certainly before rushing out to eBay to buy a new
KA655 board).
MS
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4 Jul
4 Jul
3:51 a.m.
On Fri, 2 Jul 2004, SHAUN RIPLEY wrote:
Agree. I have a VAX3900
<http://www.geocities.com/mscpscsi/VAX3900.html>. My
guess is that you have kind of 'minimal' system such
that all your boards are on the right half of the
backplane. Since no board is drawing power from the
leftside PSU it is unhappy. Solution is to add any
board for the left side PSU as I did. I used a M9060
load board.
I'd like to know if there is anything different about the BA213 backplanes
which came with the eariler? DECserver 500's. They have only a plug on
the backplane for the right power supply.
I wonder if this backplane would work on a lightly loaded VAX which makes
me wonder if there is something different about the board which allows
DCOK to work with only one H7868 power supply.
4:09 a.m.
On Fri, Jul 02, 2004 at 04:33:23PM -0700, Michael Sokolov wrote:
Dan Kolb <dankolb(a)ox.compsoc.net> wrote:
Oops. My bad. Well, bad of the website I got the info from :)
I decided to power on my MicroVAX 3800, after
it's been idling for a couple of
years (unfortunately due to lack of time on my part), only to find that it's
not booting properly. The LED display on the cover/patch panel sits saying 'F'
(apparently "Waiting for CDOK"); nothing else happens. Anyone got any ideas as
to what may be wrong, or if it's fixable?
First of all, it's DCOK, not "CDOK". Second, the problem may not be in
the CPU board, it may be the PSU. E.g., it's out
of tolerance and does
not assert the DCOK signal. Follow Tony's advice: check the PSU voltages
and the state of the DCOK signal before randomly swapping parts (and
certainly before rushing out to eBay to buy a new KA655 board).
Interestingly, having moved the CPU boards to the left-hand side of the chassis
(it was originally on the right-hand side) allows the machine to start up about
10-20% of the time, whereas before it wasn't starting at all. Would each side of
the backplane be connected to a separate power supply? Would it be at all possible
to run the machine (BA213 chassis) with only one of the power supplies (I think
it's likely that the right-hand supply is slightly dodgy)?
Dan
--
I am more bored than you could ever possibly be. Go back to work.
4:37 a.m.
Interestingly, having moved the CPU boards to the
left-hand
side of the chassis
(it was originally on the right-hand side) allows the machine
to start up about
10-20% of the time, whereas before it wasn't starting at all.
Would each side of
the backplane be connected to a separate power supply? Would
it be at all possible
to run the machine (BA213 chassis) with only one of the power
supplies (I think
it's likely that the right-hand supply is slightly dodgy)?
I don't have the IPBs in front of me but I do
think that each half is normally powered by
its own supply. There is some connection between
the two halves, however, since if the LH PSU blows,
the whole machine fails to start. Similarly, if you
have insufficient load on the LH PSU it will not
come up (SMPSU I presume) and that also stops
the machine from working (hence the need for
a load board in some configs).
I don't think I have any schematics for
this range of machines, but it sounds like
you need to fix the dead PSU.
The BA214 (or whatever the smaller cab config
was) would almost certainly have been half
the backplane of a BA213, so it might be possible
to reconfigure the existing box to run with
one PSU and half a backplane while you fix
the broken PSU. Head on over to Manx and pull
a few IPBs to see what you can do (if anything).
Antonio
--
---------------
Antonio Carlini arcarlini(a)iee.org
5:02 a.m.
On Sunday 04 July 2004 11:09, Dan Kolb wrote:
On Fri, Jul 02, 2004 at 04:33:23PM -0700, Michael
Sokolov wrote:
You could remove one power supply and then either crimp together a
splitter cable for one power supply, or just solder the connectors
together on the backplane...
Also, the power supplies, being switching supplies, need a minimum load.
Do you have boards on both halves (left/right) of the backplane? DEC
sold a "dummy load" board, which was a board with a bunch of resistors
on it, in systems that were "lightly" configured (didn't use most or
all of the left half of the backplane).
I'd recommending taking out a voltmeter and seeing if the system
voltages are "in tolerance" (within about 5% of their rating...
4.8-5.1V for 5V rail, 11.6-12.2V for the 12V rail, etc.)
Pat
--
Purdue University ITAP/RCS --- http://www.itap.purdue.edu/rcs/
The Computer Refuge --- http://computer-refuge.org
the CPU board, it may be the PSU. E.g., it's
out of tolerance and
does not assert the DCOK signal. Follow Tony's advice: check the
PSU voltages and the state of the DCOK signal before randomly
swapping parts (and certainly before rushing out to eBay to buy a
new KA655 board).
Interestingly, having moved the CPU boards to the left-hand side of
the chassis (it was originally on the right-hand side) allows the
machine to start up about 10-20% of the time, whereas before it
wasn't starting at all. Would each side of the backplane be connected
to a separate power supply? Would it be at all possible to run the
machine (BA213 chassis) with only one of the power supplies (I think
it's likely that the right-hand supply is slightly dodgy)?
7476
days inactive
7478
days old
5 comments
6 participants
participants (6)
-
a.carlini＠ntlworld.com -
dankolb＠ox.compsoc.net -
msokolov＠ivan.Harhan.ORG -
pat＠computer-refuge.org -
thompson＠new.rr.com -
vax3900＠yahoo.com