Date   : Sun, 06 Jan 2008 23:07:41 -0000
From   : C.J.Thornley@... (Chris Thornley)
Subject: Technomatic Disaster

Hi,
On inspection of there board are there any raised / domed or leaky
electrolytic capacitors?

Chris


               />      Christopher J. Thornley is cjt@...
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-----Original Message-----
From: bbc-micro-bounces+c.j.thornley=coolrose.fsnet.co.uk@...
[mailto:bbc-micro-bounces+c.j.thornley=coolrose.fsnet.co.uk@...
uk] On Behalf Of Andrew Benham
Sent: 06 January 2008 14:07
To: Ian Wolstenholme
Cc: bbc-micro@...
Subject: Re: [BBC-Micro] 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"

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