Date : Sat, 10 Dec 2005 15:43:22 +0000
From : "Ian Wolstenholme" <BBCMailingList@...>
Subject: Re: BBC B+ with faulty disc interface
I have found that the disc interface is not totally dead. If I move the drive
head along then *. will move the head back to track 0 but then nothing
else happens. The drive light goes off after about 2 seconds and there is
no response from the Beeb.
According to the service manual, links S3 & S4 should be made South for
5.25" disc interface. There is a track connecting the 2 southmost pins
on the solder side of the board for each of these links but on the
component side the links have also been made south with the
insulated wire. Could this be confusing the disc controller?
This B+ has the 64K sideways RAM board fitted. Does anybody know of a
conflict between that and the disc interface?
Best wishes,
Ian
----- Original Message -----
From: Greg Cook
To: bbc-micro@...
Sent: Tue, 6 Dec 2005 20:10:13 +0000 (GMT)
Subject: Re: [BBC-Micro] Re: BBC B+ with faulty disc interface
On Tue, 6 Dec 2005 00:49:55 +0000, Ian Wolstenholme
<BBCMailingList@...> wrote:
> Yes, I am using a known good drive and a formatted disc. There is
> not
> even a disc error, nothing happens until you press ESCAPE.
>
> I suspect it may be a botched job of a disc upgrade as links S3 and
> S8
> are made with a bit of insulated wire rather than a jumper or a
> solder track and the 1770 itself does feel ever so slightly loose.
> (It's not
> socketed).
Perhaps the connection to the NMI line hasn't been made or it's broken,
causing the controller to sulk because of late register service. (This
also happens if the controller raises more NMIs than the filing system
is expecting.) It may just be a matter of re-soldering a dry joint(s)
on the 1770 as all other mods have most likely been done.
Also IMHO using wire to make links (soldered or wirewrapped) is
legitimate and recommended, provided the wire is as short as possible.
Greg Cook
debounce@...
http://homepages.tesco.net/~rainstorm/
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