Date   : Mon, 18 Jun 2001 14:03:24 +0100
From   : Andrew Chesterton <achester@...>
Subject: Re: Faulty Vicrovitec Monitors

Hi Mike,
       Thanks for the reply. I have included answers to your questions
after the relevant sections.
Like you, I have never seen a monitor display this fault before.

Thanks,
       Andrew.

-----Original Message-----
From: Mike Tomlinson [mailto:mike@...]
Sent: 15 June 2001 20:16
To: bbc-micro@...
Subject: Re: [BBC-Micro] Faulty Vicrovitec Monitors


In article <6D293A121957D4119899009027FCB5DE0482DB@...>, Andrew
Chesterton <achester@...> writes

>Can anybody help ?

I fixed BBC Microvitecs for seven years...

>When I power on my BBC the monitor displays about a dozen small horizontal
>lines about 1/3rd of the way down the screen. The lines roughly correspond
>with the first line of text that a BBC normally displays on bootup. From
>memory I think it is the type of DFS installed.

... but this is an unusual fault.  It sounds like a horizontal sync
problem.  Is the image static or rolling?  Flickering?

The image is static

Was this sudden?  Has the monitor previously worked?  Does it make any
odd noises?  Tried another BBC?  Beep out the RGB cable with a meter -
it should be pin-1-to-pin-1, through to pin-5-to-pin-5.  Pin 6 (the
centre pin) is not used.

In Order.
I turned the monitor on for the first time in about 6 months and it was
faulty.
It has worked previously.
It doesn't make any odd noises.
I have tried both a BBC B and a Master 128, both give the same results.
I have tried two known working RGB cables, again, both give the same results

The most common fault with Microvitec Cubs were in the power supply and
in the frame circuit (the frame chip is in the back right hand quarter
of the board, and has a heatsink on it, though failure normally results
in frame collapse - a bright horizontal line across the centre of the
screen.)

-- 
"Security-wise, NT is a server with a 'Kick me' sign taped to it."
                      - Peter Gutmann