Date   : Sun, 11 Apr 2010 21:38:55 +0100
From   : dominic@... (Dominic Beesley)
Subject: Dead beeb - easy tests

Thanks Chris, Mark,

Cigar goes to Mark - tried S25 and BRrr-beep

Now...how to track down which chip is at fault is it possible to access them
when the machine's running in 16k mode?

Dom

> -----Original Message-----
> From: bbc-micro-bounces+dominic=brahms.demon.co.uk@...
> [mailto:bbc-micro-
> bounces+dominic=brahms.demon.co.uk@...] On Behalf Of
> Mark Haysman
> Sent: 11 April 2010 19:33
> To: bbc-micro@...
> Subject: Re: [BBC-Micro] Dead beeb - easy tests
> 
> > My London based beeb has decided to pack in this weekend. Symptoms
> are
> > continuous beep at switch on, Caps lock on from start shift lock
> comes on
> > after 1/2 second.
> >
> > Tried swapping 6522s no difference.
> >
> > No cursor on screen but I think the processor is doing something as
> the
> > shift lock ceases to come on if 6502 or LS245 are removed.
> >
> > Any ideas of simple tests without any test gear...if not it will have
> to
> > come back to civilisation where I can show it to a scope...
> 
> Swapover the link at S25, that changes it to 16K, and swaps the RAM
> bank
> used for zero page, sometimes that shows up a RAM fault. Removing the
> LS245
> will make it a-la-dodo, as it needs that to interface to the RAM, so
> try
> swapping that out if the 1MHz bus one is socketed.
> 
> Mark.
> 
> 
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