22 Aug
2011
22 Aug
'11
5:18 p.m.
On 22/08/2011 23:20, Rob Jarratt wrote:
I am a bit confused about this. I have an MicroVAX II
in a BA123 enclosure
with an RQDX3 which has a problem with not seeing the disks (which I know to
work), when I try to boot from a disk I get DEVINACT. I am beginning to
suspect a fault in either the RQDX3 or the M9058. I decided to make sure
that the cable between them was the right way round as the cable I have does
not have keyed connectors. Here is where I get confused.
Can anyone confirm that I have the cable oriented
correctly in the BA123? In
other words pin 1 at the bottom of the connector on the RQDX3 itself when
installed in its slot, and on the M9058 pin 1 on the left of the card when
viewed component side with J12 at the top (ie at the top again when the
M9058 is mounted in its slot)?
Looking at the drawings I made of the M9058 many years ago, that looks
correct, but my drawing of the layout just shows the arrows that are
usually marked on the connectors. I no longer have an M9058 so can't
check directly. Fortunately, there's an easy way to tell which end of
the J12 connector is which, if you have a ohmmeter.
On the M9058 J12, pins 1, 2, 3, 4 and 50 are (different) signal pins.
Pins 45, 47, and 49 are all ground. Remember that all the odd-numbered
pins are one row and all the even-numbered pins are the other row. So
find three pins at one end that are all connected together and you've
found pins 45/47/49, and therefore can determine that the pin in the
same row but at the opposite end is pin 1. Ditto for the RQDX3 itself.
BTW, all the odd-numbered pins on J1, J2, J3, J4, J9 and J11 are
ground as well.
The relevant diagram is at
http://www.dunnington.u-net.com/public/RQDX/M9058_schematic.pdf
and the other files in the same directory are some other relvant
diagrams and pin descriptions.
--
Pete Peter Turnbull
Network Manager
University of York