[unix-pc.general] Interesting Backplane

roger@banzai.UUCP (Roger Florkowski) (04/24/89)

Ok netlanders, here is a picture describing something unique about
my 3b1.  There I was installing a new motherboard,  and I noticed
something about the back metal plane that I hadn't seen on any
other 3b1 I had taken apart.  The back plane was extended across
on the right hand side (underneath the floppy drive), and it
contained a large cut out.  Normally the back plane drops down
as I show on the left side.  Now, this cut out cannot be seen
when the cover is on because the fan grate covers it.  Has anyone
else seen anything like this?  

The machine has a 67 meg drive and a high serial number. 
Under the cover there is writing dated April 1986,  so that
puts it towards the end of the production run of these machines.

A funny coincidence is that I was planning on adding a second hard
drive this summer.  All that I have to do for cabling is cut away 
the fan grate and drop in a socket!


                       phone       parallel     serial        UNKNOWN
                screw  jacks         port        port  screw  CUTOUT!!
                 |--------------------------------------------------------
 ________________| o [_][_][_]  [____________] [_______] o  [__________] |
|                                                                        |
--------------------------------------------------------------------------
|    Expansion #1       |      Expansion #2       |    Expansion #3      |
|                       |                         |                      |
--------------------------------------------------------------------------


-- 
Roger Florkowski	       		{uunet!uvm-gen, attmail}!banzai!roger
The People's Computer Company			  `Revolutionary Programming'

thad@cup.portal.com (Thad P Floryan) (04/26/89)

In re: Roger Florkowski's comments about a cutout in his 3B1 ...

Mine has the same thing.  It is EXACTLY the correct size for a 50-pin
Centronics SCSI connector!  :-)  Even has the slots for the two screws.

Since the 3B1 doesn't have a fan in that location, it would seem that the
International cover would be the thing to get.  In fact, looking at the
drawing of the back of the International section of the UNIXPC Reference
Manual, there is a metal plate there with two screws fastening the plate
to hide the cutout.  The cutout is immediately to the right of the TTY000
RS-232-C port connector and the rightmost (of the two rear plastic cover
screws) fastens right smack dab between the RS-232 and the "other" cutouts.

That cutout is just NOT documented.  But it's there.  A perfect location for
a SCSI connector.  Now, just to locate "International" covers.  :-)

If anyone (in N.Calif) wants to bring their 3b1 to the May meeting of the
Bay Area AT&T Computers Users' Group, we can open it up.  I intend replacing
the clock battery in one member's 7300 with a socket and replacement battery
right there in the meeting (takes about 20 minutes), so we can open up
UNIXPCs "just to see what's there" while I talk about uucp and the UNIXPC.

Thad Floryan [thad@cup.portal.com (OR) ..!sun!portal!cup.portal.com!thad]