Date   : Sat, 30 Oct 1999 17:32:12 +0200
From   : "Mark Usher" <marku@...>
Subject: Re: Further investigation 

> Did you say you had swapped the LM319 chips for those in another
> machine?  If not, give that a go.
Yes, all have been swapped.

> I guess IC91 might also be faulty.
> Assuming the '319s
> are socketed, pull out IC55 and check that you now get 5V on IC91 pin 5.
er IC 95. Yes, pulling that out gives me 5v on IC 91 pin 5.

> Also, do you know if the Econet interface has ever worked in this
> machine?
Yes it did for a few weeks.

> If not, it could be that the upgrade was botched.
I did the upgrade so you could well be right.

> The 2% resistors in the
> analogue side are quite critical; some machines had 10% tolerance
> parts fitted which are no good.
All resistors that are fitted are 1% high tolerance resistors. What I'm
going to do is first re-solder all the resistors and then if that doesn't
work, remove them and check that they're ok with the multi meter. Or is
there a way to check them in situe ?

Mark