Date   : Sun, 06 Jan 2008 14:06:46 +0000
From   : adsb@... (Andrew Benham)
Subject: Technomatic Disaster

Ian Wolstenholme wrote:
> I've established that it's the host adapter which is faulty.  The Technomatic
> drive and Adaptec board work fine when connected up to another host
> adapter.

Hmm, there's nothing on the host adaptor to go wrong...

> Is there any way I can test the host adapter further?  All the ICs are
> registering 5V, some of the resistors are and some of them aren't, that
> might be something to do with it.  There's no obvious damage to the
> board and nothing happened that I know of to cause it to fail suddenly.

I'd check for dry joints as a first pass.

I've come across plastic-packages 74 series TTL suffering from internal
rot if not used for many years (I guess the plastic package isn't
perfectly sealed), but I understand this board failed whilst it was in
use.  So we can discount that.

If the board doesn't have any dry joints (and these can take years to
announce themselves), I'd put a scope on the address decode logic on
the host adaptor and run a tight machine-code loop first reading and
then writing from the 4 addresses (FC40 - FC43) in turn - WITHOUT the
Adaptec board connected (just in case).

If all the address decode logic is OK, it's more or less down to the
various buffers.

-- 
Andrew Benham         adsb@...       
Southgate, London N14, United Kingdom

The gates in my computer are AND OR and NOT, not "Bill"