Subject: Re: Sun 3/280
To: Hakan Thorngren <>
From: Greg A. Woods <>
List: port-sun3
Date: 07/16/1997 11:59:45
[ On Wed, July 16, 1997 at 13:53:21 (GMT), Adam Kropelin wrote: ]
> Subject: Re: Sun 3/280
> Hakan Thorngren wrote:
> > 
> > There is a possibility that I can obtain a Sun 3/280, but I do not know
> > how complete the machine is.  I had a look at it yesterday and if I
> > describe it, maybe someone who are familiar with it can enlight me?
> I'm not as much of an expert as some folks on this list, but I'll give
> it a shot...

I'm (effectively) typing this message to a Sun 3/280 w/ 128 MB RAM
running SunOS-4.1.1_U1.  Just a couple of weeks ago the chassis that
surrounded this machine was a Sun 3/260, but I needed some more floor
space and wanted better cooling for all that memory so I've mounted the
same hardware in a 3/280 and then into a spare Digital PDP11 19" cabinet
with an extra blower in the top to increase the air flow....

I've also got a 3/60C motherboard plugged into the last two slots of the
same chassis to share mounting hardware and the power supply.

The beauty of the rack cabinet is of course I've now got everything
(almost) securely mounted in one cabinet with filtered air and all!
I still need to buy a rack-mount disk chassis for the tapes and disks,
etc. as the 280 chassis only really has the ability to mount the 60MB
tape and controller (or some other 5.25" full-height device).

My only complaint about the 3/280 chassis is that it doesn't have normal
standard slide rail mounting, but rather sits on two custom angle-iron
rails that I'm missing, so I had to just use the front vertical rail
mounting and that's a bit tricky if you want to access the backplane
jumpers (and the tape chassis, etc. but still want to have the solid
metal inner plate for protection.  Sun assumed you would configure,
install, and seal up the machine and never touch it once it's running
unless you take a major maintenance downtime to rip it all appart.

I'm thinking of bolting on rails anyway or making my own angle-iron
rails because I'd really like to have ability to remove the inside front

> > The machine appears to be "naked" without disks and tape.
> Just makes it more fun!

Aye!  But without the tape chassis you'll definitely need to resort to
externally mounted peripherals (unless you just net-boot it....)

> > 3. Is it possible to buy a memory board for it today at a reasonable price?
> I've never tried. A good place to buy used Sun stuff is the Sun 'wanted'
> newsgroup: comp.sys.sun.wanted.

I paid about $500CDN for the four surplus 32MB boards that give me the
maximum 128MB configuration....

> > 5. How should the front be attached?
> If you're referring to the plastic faceplate, mine just snaps on.

My cosmetic faceplate is actually metal, but yes it just snaps on.

> > 7. There are SCSI In/Out connectors on the back, what are they for?
> I'm not sure about this. I don't think I've ever seen a SCSI board with
> IN and OUT connectors. Are you certain this is a SCSI board?

Those IN/OUT connectors are actually for the tape chassis, so I guess
you do have a tape chassis and maybe even a drive.

The SCSI host adapter would be in slot 7 with a single DD-50 connector.

> > 8. Is it very power hungry?  I do not want my elctricity bill to sky-rocket...
> I don't know. Someone else have an idea?

Yes, they can be.  The power supply is about 850W max., though according
to the config guide they're only rated for 690W continuous load because
of cooling restraints.  I don't think this is as true for the 3/280, but
is definitely true for the 3/260.

A pair of 3/260's and a 3/60 effectively doubled our monthly bill.

Note that when you see the DC power cables and rails on the backplane
you should be afraid of them -- that power supply can deliver 120A at
5VDC.  That's probably enough to melt a medium screwdriver if you short
the two main terminals (though hopefully it shuts itself down with a
current-limiter in a full-short condition -- they appear to be well
designed switching power supplies).

The CPU board alone draws 22.5A @5VDC (115.6W total), and the memory
boards of various capacities average about 70W total.  A CG2 colour
board (if you have one) draws 107W total.  The SCSI card a mere 24W.

With all that power the machine radiates as much as 3000 BTUs/hr, which
compares to about half the capacity of a normal small window air cond.

There are NO fans for the 3/280 chassis itself (the powersupply contains
its own fan but that doesn't in any way cool the cards) and it MUST have
adequate cooling. In comparison the 3/260 chassis has six fans in a tray
that suck air down through the card slots from the already pressurised
(by two more top-rear mounted fans) top compartment.  With my cabinet
config I've two full 10" fans blowing filtered air down through my
chassis and the rest of the rack.

I've seen these machines (3/260's actually) run A-OK for many months in
rooms with ambient temperatures approaching 90 d. Fahrenheit, but they
would have melted internally without the air convection keeping
everything the same even temperature.  Modern silicon electronics *can*
run at high temperatures, but most of this commercial gear was probably
designed to run at ambient temperatures of about 65 F. with lots of air
convection for adequate heat transfer.  Sun claims the operating
temparature range for most of their equipment is 0 C. to +40 C though
even I don't operate at +40 C! :-)

Note that even a 3/260 chassis is very noisy with all those fans too
(and the power supply fan is often the most noisy).  You probably don't
want one next to your desk unless there's a lot of noise already in your
environment, and you certainly don't want one in your bedroom!  (When I
had a 3/260 for a workstation in the office next to the bedroom I had to
close the office door every night!)

							Greg A. Woods

+1 416 443-1734      VE3TCP      <>      <robohack!woods>
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