'not well' Osborne 1 mk 2

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Sun Jan 18 17:15:43 2004

>
> > > They are indeed 4116s, my comment on the glue gun was there
> > because 3/4 of
> >
> > In which case you can check the +5V, +12V and -5V rails at pins on the
> > RAM chips.
>
> All check out fine on multiple random tests, though I have to admit I'm
> sitting amongst the smell of singed plastic since it seems the interior of
> the machine has been metallised somewhat :-/ It didn't do that yesterday! Oh

Err, what????

> well, I'm still with the same problem.....fortunately I saw smoke before
> anything nasty happened!

And from where did this (magic) smoke come? You do, of course, realise
that it's smoke that makes electronic devices work -- when the smoke
comes out they stop working.

>
> > rails. In other words, you only need to check the voltages at one of the
> > RAM chips (assuming there are no cracked tracks on the mainboard, but I
> > wouldn't worry abnot that yet!).
>
> OK, so far we have +5V, clock signal and active address and data lines, or

Did you check the other voltages at the RAM chips (-5V on pin 1, +12V on
pin 8, +5V on pin 9, ground on pin 16)?

> at least my probe makes the expected noises once I found somewhere to get a
> good 5V supply from, so I'd say the CPU is running and I have a problem
> after that. Normally at this point I'd go for video RAM, but the only
> obvious culprits for that are a pair of 6116s that live on the other

6116s are normally darn reliable.

If those _are_ the video RAMs, are you getting activity on their address
and data lines? In other words, is the video timing chain running.

What, if anything, do you get on the screen?

-tony
Received on Sun Jan 18 2004 - 17:15:43 GMT