Blower/airflow sensor needed for BA32

Ethan Dicks ethan.dicks at
Thu Mar 16 01:17:49 CST 2006

On 3/16/06, Robert Armstrong <bob at> wrote:
>   The BA32 is the baby VAX BI chassis used in the 8200/8250/8300/8350
> systems - I have an 8250 (it'd be an 8350 if I could find another CPU :-)

Mine's an 8300 because I don't have any 8250 CPUs.

> that has some problem with the cooling.  The blower speed seems to vary all
> the time it's running, and it's constantly speeding up and slowing down.
> The system wil run for about an hour and then trips itself off, presumably
> either because of airflow or overtemp.
>   Can anybody tell me if the blower speed is supposed to vary like that?

Hmm... I don't remember the fan speed varying on mine, and the airflow
sensor is pretty sensitive - if you leave the lid off, it should trip
the box in well under a minute.  We had to make a cardboard sheild
when I did VAXBI board production - to let us have our analyzer pods
and ROM emulator pod stick out.

> Does anybody have any maintenance prints for the BA32 blower control?
> Anybody got any spare parts they're willing to sell?

Unfortunately, I have no prints and no spares.

>   I spent a long time putting it back together after it'd been stripped by a
> scrap yard, and I've actually got it to the point where it will boot VMS
> now, so I'd really like to fix this last problem.  Besides, it's a really
> cute little system

I certainly like mine. I wish I could figure out why the DWBUA won't
pass onboard diagnostics - perhaps I have 3 dead UET cards (Unibus
Exerciser/Terminator - it has to be present and functional for the
DWBUA to report 'all clear').

If you just want to play with BI machines, it's a fun little box.  The
two most common ways I know of adding disks are either the KDB50 MSCP
controller or stick it on an HSC50 and use clusterable disks.  There
_are_ VAXBI SCSI cards, but back in the day, they were like $10,000. 
I've never held one.

> ... I believe it's the smallest VAX BI box around.

That and the VAXstation 8000.  No other machines that I know of are
100% VAXBI - the 85xx/87xx/88xx are Nautilus Bus based with a BI
adapter, similar for the 6xxx series (XMI w/bus adapter).  I used to
have an 8550, but it didn't survive a move 13 years ago.  The 8300 was
easy to stick in the back of my VW microbus (and is in my basement
now, hooked up and powered down).


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