Date   : Mon, 01 Nov 1999 12:11:24 +0100
From   : "Mark Usher" <marku@...>
Subject: Re: Further investigation 

A singed finger tip, and a stiff neck later...

> You should get fairly good results just checking them in circuit
> without doing
> anything special.  But yeah, I'd look for dry joints first.

Checked round and everything seems to be fine.
Did a some multi meter tests... and did them again after disconnecting the
econet lead...

                             bad bbc       good bbc
IC95 pin 5 - IC94 pin 5      66.2Kohms     72.6Kohms
IC95 pin 5 - IC95 pin 10     86.4Kohms     87.4Kohms
IC95 pin 7 - R61             996           1011
IC95 pin 12 - R61            996           1011
IC95 pin 9 - R64             29.88K        33.0K
IC95 pin 4 - R64             29.88K        32.7K

IC94 pin 4 - R41             99.6K         98.9K
IC94 pin 5 - R40             99.4K         99.5K
IC94 pin 4 - IC94 pin 12     10.53K        10.76K
IC94 pin 5 - IC94 pin 12     10.00K        10.8K
IC94 pin 12 - R46            1000          996
IC89 pin 3  - R46            1000          996

IC91 pin 5 - R61             997           1011
IC93 pin 12 - IC94 pin 4     99.2K         98.9K

This seems to suggest that the connections are ok, as are the components.
I also tested the DFS just to make sure, and that seems to be working OK.

So, the machine hangs when 8271 is fitted, and boots OK when it is removed.
The machine hangs when S2 is removed (the Econet NMI) but boots when fitted
(disabled).
When booting without the econet enabled the DFS functions as expected.

Time for another look through the circuit diagram.

Mark