12 Dec
2002
12 Dec
'02
8:40 p.m.
On Dec 12, 19:43, Joe wrote:
Nope, all the RAMS are soldered directly to the
board and no solder
flux. I'm sure it was built with 32K and that appears to
agree with the US
model number.
Yes, I'm sure it is, I was just pointing out that in the general case,
amount of memory is not a good way to tell. AFAIK, Acorn sold only Model
Bs in the States.
It's not running at the moment but when it was
it said soemthing
like:
"Acron version 2.1
DFS OS
BASIC OS"
There's also a EPROM that says "DFS OS" in it so I think it's
supposed
to say that.
I've not seen a US model start up, but I expect Acorn removed the "BBC
Microcomputer" part for trademark reasons (in many countries outside the
UK, BBC is a trademark of Brown Boveri & Cie, and anyway it wouldn't mean
the same in the States). Presumably they changed the other strings too.
How many (EP)ROMs are in it? Do they have any numbers on them?
OK thanks for the pointers. I searched the net but
found so many
sites that I haven't had time to go throught them all.
If you're looking for repair information, the ones I listed are good places
to start. You might also consider joining the BBC mailing list. If you
want to, send a message with "subscribe bbc-micro" in the body, to
majordomo at cloud9.co.uk.
Nope, that's not what I got. It didn't say
anything about BBC or
Microcomputer or the amount of memory and it definitely said
"OS" twice. I
did get the beep then the speaker had a slight buzzing in it. (Possible due
the the failing capacitor in the PSU). I was in the process of checking
the PSU outputs for noise when the cap blew. It was quite noticeable!
Maybe they changed the banners more than I thought.
Actually I didn't get a cursor. I wasn't
sure if it was supposed to
have one or not.
Yes, you should.
Thanks for the description. That's about what I
expected. Sounds like
I need to find a VIA. I need one for my spares anyway. There
are two
mylar(?) ribbon cables that connect the keyboard to the main circuit board.
Is the wide one the column inputs and the narrow one the row outputs?
(Keeping my fingers crossed that it's that simple!)
I doubt if it's that simple. UK models don't use mylar ribbons, they use a
single 17-way notched IDT cable with a 0.1" pitch, and with a single-row
Molex IDT header at each end. If the cable is damaged you can use ordinary
34-way cable with 34-way 2-row IDC headers; just ignore the second row.
Download the service manual; it has the keyboard diagram, with pinouts.
Fix the PSU first, obviously. The Beeb is a bit choosy about power
regulation, and if the 5V and 0V connectors (of which there are three
pairs) don't all make good connections to the board, you can get strange
faults because the voltage may be too low at some points on the board. The
red and black wires are +5V and 0V respectively. There's a purple wire for
-5V, but this is only used for the serial port and audio amp. There's a
+12V output but only on the AMP connector at the front, as it's only needed
for peripherals.
--
Pete Peter Turnbull
Network Manager
University of York