Date : Sun, 27 Jul 2008 15:20:25 +0100
From : bbcmailinglist@... (Ian Wolstenholme)
Subject: BBC B+ Disc Fault
The DFS has never worked as long as I have had it, but I think the previous
owner thought it was working, so it may have become damaged in transit.
When I opened it up last night, it had two DFS ROMs, an original Acorn
DFS 2.0j in EPROM and DFS 2.22 which I programmed myself. I can't
remember if it came with DFS 2.0j, which doesn't have the SRAM utils,
so the Beeb reports itself as Acorn OS 64K when using this one, which
would appear to be a bit strange since the SRAM on the daughterboard
wouldn't be useable without third party utilities. It's also possible it had
no DFS in it and I put in DFS 2.0j from somewhere else.
Anyway, that's a side issue, I've tried it using each of the DFS ROMs
separately and the same thing happens.
Best wishes,
Ian
----- Original Message -----
From: Mark Haysman [mailto:jumbos.bazzar@...]
To: bbc-micro@...
Sent: Sun, 27 Jul 2008 15:03:32 +0100
Subject: Re: [BBC-Micro] BBC B+ Disc Fault
Hi.
Did it come to you in a non-working condition, or was it working one day,
then all of a sudden stopped? The reason I ask is if it came to you broken,
have you checked things like a bent or pushed in pin in the 34 way
connector? Is there other track damage around the broken VR1?
If it was working and suddenly stopped, check the EPROMs (and any other ICs
in sockets) have not come dislodged - reseat them a few times, and if
possible, verify the DFS rom to ensure it's not started to lose it's
program. Apart from that, it's get the scope out time, unless anyone else
has some suggestions. Myself, along with a few others in here I'm sure would
repair it for you if need be.
Mark.
----- Original Message -----
From: "Ian Wolstenholme" <bbcmailinglist@...>
To: <bbc-micro@...>
Sent: Sunday, July 27, 2008 2:52 PM
Subject: [BBC-Micro] BBC B+ Disc Fault
I have a BBC B+ 128K, complete with the 64K daughterboard and
1770 disc interface but unfortunately, the disc interface doesn't
seem to work.
DFS will attempt to access the disc for about two seconds and then
the drive light goes out and nothing else happens, the Beeb just waits
there and doesn't come back with an error message or anything.
I checked the disc interface against the fitting instructions in the
Service Manual and all the chips and link settings are present and
correct.
The only obvious damage to the motherboard is that variable
resistor VR1, just below the speech sockets, appears to be broken
but I don't think that's related to the disc interface.
It has had a replacement PSU at some point in its life, it is date
coded 8718, well after production of the B+ ended. I wonder if
the PSU blew and could have blown the disc interface chips?
Is there anything obvious I can try or check, such as checking
the disc chips for voltages?
Best wishes,
Ian
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