Date   : Sun, 14 Aug 2011 22:57:19 +0100 (WET-DST)
From   : BBCMICRO@... (Peter Coghlan)
Subject: Advice on restoring a dead Beeb?

>
>Power on.  I'll establish what the behaviour is with a break-induced reset.
>(All I recall from when I tried it without a logic probe to watch was "nothing
happens" so
>I'll need to do that again just a little more rigourously.)
>

Ok. So when you power on, you get the usual random drone noise which stops
after the
usual second or so and you don't get the expected beep afterwards, just silence?

And when you press break or control-break you just get silence, no beep?

>
>I have  British Beeb here, and an old NZ portable TV given to me by a colleague
with
>some muttered warning about how the UHF spectrum here is different to that
in the UK.
>I did, of course attempt tune the TV in (after disconnecting speaker to
get rid of that
>hideous droning noise and the best I could do was a black and white (yeah!)
barbershop
>pole type display.  More black than white, could have been a flash cursor.
 Or next
>week's winning lottery numbers, who knows.
>

Do you mean the noise is coming from the speaker in the Beeb or the speaker
in the TV?
Noise from the TV speaker is expected as the Beeb does not include sound
on the TV
output so it is a good idea to turn down or disable the sound output from the TV.
A continuous drone from the Beeb speaker indicates that the sound IC is not
getting
reset at power on.

Other than the channel/tuning issues and differences in the sound frequency
which is
not used by the Beeb, the NZ and British TV systems are very compatible.

A British Beeb TV output would normally be on UHF channel 36. As far as I
can tell
from google, NZ UHF channel 36 is the same as UK channel 36 (591.25 MHz).
Can your TV
tune to that channel/frequency? If the TV only does VHF then it may not be
suitable.
Some TVs do not display the signal from a Beeb well, even when they do cover the
required channel.

If the TV has a composite video input, you could connect that to the BNC
socket labelled
"video out" on the back of the Beeb and avoid any tuning problems and get
a much more
useful (although monochrome) picture for less hassle. Another alternative
would be using
a closed circuit TV monitor.

>
>Wait up -- I took a picture the very first time I opened it.  Mobile phone,
poor quality,
>but I'll dig it out.  Here:
>
>http://jessies.org/~car/misc/20110815-bbcmicro/IMG_0994.jpg
>
>There are two identical ROMs (in appearance) in the bank of five, and I
foolishly pulled
>all three ROMs (one labelled DFS) when I did my reseatathon.  I couldn't
determine which
>of the two doppelgangers was which, but my fuzzy knowledge and a paw through
some manual
>(yet to be identified) they must be MOS and BASIC, no?
>

The DFS is in a reasonable position. The OS ROM socket is also occupied -
this is also good.
The two similar ROMs should have slight variations in what is printed on
them giving clues
as to which is which. However, I can't make out the numbers from the photo.

>
>And getting "further" by flashing lights diagnosis, I assumed that they're
now in the right order.
>

Maybe :-)

>
>please accept my apologies for not quite keeping up with this after asking
the question --
>I was waiting for a lull and some matching spare time.  Still waiting for
that spare time.
>

No bother. It took me as long to reply to the initial question :-)

Regards,
Peter Coghlan.