23 Aug
2011
23 Aug
'11
2:30 a.m.
-----Original Message-----
From: cctalk-bounces at classiccmp.org [mailto:cctalk-
bounces at classiccmp.org] On Behalf Of Pete Turnbull
Sent: 23 August 2011 01:19
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Cabling RQDX3 to M9058
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.
usually
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 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
Thanks very much for the information. I found the three pins which are
shorted together and the ribbon is connecting them correctly, it is just
that the ribbon is the wrong way round, with the red stripe on the high
numbered pins.
I now need to check if the ribbon itself or the RQDX3 or M9058 is faulty. I
have a spare RQDX3 to try with but no spare M9058, so lets "hope" it is the
RQDX3!
Regards
Rob