Date   : Sun, 29 Jul 2001 16:43:18 +1200
From   : Michael Foot <mikef@...>
Subject: Re: Help with BBC B fault

In message <7qzdunCEZsY7Ewwb@...>
          Mike Tomlinson <mike@...> wrote:

> In article <20010727042234.MNMQ18810.mta01.mail.mel.aone.net.au@...>,
> mikef@... <mikef@...> writes
> 
> In order:
> 
> Take out the user 6522 (this is below the 6502 and provides the user and
> printer ports)
> 

[snip]

> Check IC14, 74LS245 - to the right of the 6502.  If this is socketed,
> try replacing it.  It's a common failure point.  Do not use a substitute
> - e.g. 74HC245, 74ALS245.

Thanks for the suggestion. I've tried what you suggested, but it did not
change anything. I even tried closing link 9 (disable NMI) and replaing IC14
but things are still the same.
I guess it's either some unsocketed IC, or another component such as a resister
or capacitor which has failed. If it is, it's going to be very hard to hunt down.

> Was the machine known to be working previously?

Yes. In fact it's condition is (was) mint and it still has the original packaging.

Mike.

-- 
Michael Foot <mikef@...          >
http://www.voyager.co.nz/~mikef