17 Jan
2004
17 Jan
'04
5:36 p.m.
-----Original Message-----
From: cctalk-bounces(a)classiccmp.org
[mailto:cctalk-bounces@classiccmp.org]On Behalf Of Tony Duell
Sent: 17 January 2004 22:54
To: cctalk(a)classiccmp.org
Subject: Re: 'not well' Osborne 1 mk 2
Yes, that's what I'd do. Check the 5V line at a known chip (CPU, or a TTL
device). In a machine of this type, there'll only be one 5V line (unlike
in my 11/45 where there are several, from separate PSU bricks...).
I don't know what the RAMs used are, but if they're 3-rail types, like
4116s, you should check the other supplies there too.
They are indeed 4116s, my comment on the glue gun was there because 3/4 of
the RAM is obscured by (I'd guess) the floppy drive connector board that is
sat in mountings glued to the motherboard. Still, I don't need to remove
it....yet....
If the PSU lines look good, then check that the CPU is
getting a clock
signal. Look also for activity (changing singals) on the address and data
lines from the CPU.
That was next on the list :) I must advance plans to sell things to let me
get a good bench PSU and 'scope - watching an electronics pro work on a
machine the other day showed just how important they are!
cheers
--
Adrian/Witchy
www.binarydinosaurs.co.uk - possibly the UK's biggest online computer museum
www.snakebiteandblack.co.uk - ex-monthly gothic shenanigans :o(