Date   : Fri, 27 Jul 2001 10:18:01 +0100 (GMT+01:00)
From   : Chris Thornley <c.j.thornley@...>
Subject: Re: Help with BBC B fault

Hi,
Have you tried replacing the keyboard connector? try reversing it to see
if the fault shifts.
Are all jumpers correctly set on board? Was anything like a swr module removed

Chris

----- Original Message -----
From: "mikef@..." <mikef@...>
To: <bbc-micro@...>
Sent: Fri, 27 Jul 2001 05:22:49 +0100 (GMT+01:00)
Subject: [BBC-Micro] Help with BBC B fault

> Hi,
> 
> I've been given a BBC B which I'm trying to get working again. It's suffering
from the dreaded single 
> continous beep fault. I know this symptom is quite common when the B fails
and I have tried all the 
> normal fixes I can find. It is a standard Issue 7 board with 8271 upgrade.
So far I have tried:
> 
> replacing the keyboard
> replacing the power supply
> replacing all the socketed chips (6502, 6522, Video ULA, OS ROM etc.)
> changing the memory bank jumper (25) to all 3 combinations
> 
> I don't have an oscilliscope or a logic probe, just a multi-meter, so it's
difficult for me to test the 
> circuit board directly. I did notice that the current from the jumpered
pins of PL25 to the unjumpered 
> pin was oscillating quite noticably, if that means anything.
> 
> Can anyone suggest other things to try that may solve or narrow down the
problem? Could it be a faulty 
> SA5050? Also, what happens between the machine issuing the first and second
beeps?
> 
> Thank you,
> 
> Mike.
> 
> __________________________________________________________
> Message sent by MyMail http://www.mymail.com.au/




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