Date   : Thu, 25 Jun 2009 21:48:30 +0100
From   : dm.hunt@... (David Hunt)
Subject: Only one beep

>Hi all,
>
>New member here... I'm trying to get my old model B working - it's my
>original one from the early 80s that I've recently got out of storage.
>It's not working reliably so I'm hoping to get some troubleshooting tips.
>
>A coulpe of months ago, I switched it on and it started up fine, showing
>the usual welcome notes and command prompt.  I had barely had time to type
>'10 PRINT "HELLO" 20 GOTO 10' before it froze up and would not reboot.  I
>suspected a loose connection going bad as the machine heated up, but since
>then it has refused to start up even from cold.
>
>The current syptoms are that, on switching on, I get the first low beep but
>not the second higher beep - does that indicate a specific fault?  The caps
>lock LED coms on, and toggles as expected when I press the CAPS LOCK key.
>The video displays nothing but a grey smudge at the top of the screen.  I
>can hear the usual faint buzz from the speaker that I remember was always
>present.
>
>I've checked the PSU outputs with a multimeter, getting +4.8 volts on the
>+5 lines and -5.7ish volts on the -5 line - are these voltages within
>limits?  I don't have an oscilloscope so can't check any timing signals
>etc.
>
>Any pointers would be gratefully received.  The machine has a debugger ROM
>in it which may prove historically interesting if I can ever get the thing
>working!
>
>Cheers,
>
>Chris.

I'd push down on all the IC's in sockets, they work themselves loose over
time. Reseat the keyboard connector too. Check out Sprow's page at;

<http://www.sprow.co.uk/bbc/doctor.htm>

It has some handy tips to get you going.

Cheers

Dave