Date   : Sun, 27 Jul 2008 15:06:31 +0100
From   : bbcmailinglist@... (Ian Wolstenholme)
Subject: BBC B+ Disc Fault

The PSU just popped whilst I was sending this message!

Then it was dead for a few minutes, continuous tone only, but
now it's back.  For the time being at least!

Best wishes,


Ian
----- Original Message -----
From: Ian Wolstenholme [mailto:bbcmailinglist@...]
To: bbc-micro@...
Sent: Sun, 27 Jul 2008 14:52:31 +0100
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