Date   : Fri, 17 Aug 2007 10:53:59 +0100
From   : itonks@... (Ian Tonks)
Subject: Troubleshooting Techniques (was: Acquired Beeb with

This thread has got me thinking about a dead Master I've got lying around.
It appears to not boot because the 6502 is not starting because the reset is
being held high.

The problem I'm having is trying to identify where the problem is. On a BBC
BI can merrily pull chips until the line goes low, but the master is mostly
soldered in.

Has anyone got any troubleshooting tips that might help me work out what's
wrong (I did change the 555 timer because that's socketed, but no joy)

Cheers,

Ian

-snip- 
>
>See, that is strange. I'm not quite sure why removing the ADC would
>partially 
>fix it, as the ADC doesn't appear to generate interrupts anyway - it's
>purely 
>polled by the system.
>
>What was the figure above for no changes and FDC in? Or doesn't that make
>any 
>difference?
>
>If you've got a multimeter, checking that the +5V power rails are behaving 
>themselves is probably a good check; I've seen flakey power supplies do
>some 
>really weird things to systems before and it'd be an easy one to rule out
>(if 
>you have a meter!). The fact that pulling random chips seems to make a 
>difference just makes me wonder if it's not actually an interrupt problem 
>(although I'd agree with Sprow; that would have been my first assumption
>after 
>ruling out the PSU)
>
>cheers
>
>Jules
>
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