Date : Mon, 14 Sep 2009 13:26:48 +0100
From : dominic@... (Dominic Beesley)
Subject: Mouldy beebs!
Thanks to everyone for the tips on cleaning, I think I've cleaned and dried
this one about as thoroughly as I can - though there will still be some
stuff lurking under a couple of the components I should think.
What I really could do with help with is tracking down problems areas and
getting it to work again! I've got a scope(s) and a multimeter and until
Friday - well at least until I have to tidy up when the missus gets back...
I got a scope out last night and the reset appears to work and there is a
reasonable looking clock on the right pins.
After a cold start the lights (and sound) are a bit random sometimes a loud
beep, sometimes a cacophony of other noises and the LEDs are random too
though it tends to be only cassette motor or caps lock that are on and they
usually go out fairly soon
no change when break is pressed though when I scope the reset or any of the
data / address lines it is obvious that it is trying to reset.
Most times if I scope a high address line there looks to be a pattern so it
appears to me that it is getting into a loop of some sort. Though it is not
always the same loop after a reset.
These machines are all fitted with Watford DDFS and Econet. Would it be
worth butting these back to a base setup?
Scoping the composite video output and modulator there is nothing but noise
which shows up on a telly as a black background with a fair bit of noise.
Supply voltages are about spot on (4.97V) and steady, none of the chips gets
hot but the 6502 gets to just below body temp and the video processor gets
warm.
Dom
-----Original Message-----
From: bbc-micro-bounces+dominic=brahms.demon.co.uk@...
[mailto:bbc-micro-bounces+dominic=brahms.demon.co.uk@...] On
Behalf Of Rick Murray
Sent: 14 September 2009 01:09
To: BBC MailList
Subject: Re: [BBC-Micro] Mouldy beebs!
Pete Turnbull wrote:
> liquid and use a soft(ish) washing-up brush. In extreme cases a
> dishwasher does a good job (but try to avoid the very hot drying cycle
> at the end of the normal wash process).
!!!! A Beeb in a dishwasher?!? Well, don't that just beat all....
As for the beeeeeeeeeeeeeeeeeee..., possible fault in the reset
circuitry (starting at the area around the itty-bitty 555 timer)? Is
there any other observation (anything on-screen, LEDs)? Perhaps also
there is gunk stopping the crystal oscillator from clocking the machine
correctly/at all?
Best wishes,
Rick.
--
Rick Murray, eeePC901 & ADSL WiFI'd into it, all ETLAs!
BBC B: DNFS, 2 x 5.25" floppies, EPROM prog, Acorn TTX
E01S FileStore, A3000/A5000/RiscPC/various PCs/blahblah...
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