Date   : Thu, 12 Mar 2009 09:30:57 -0000
From   : michael.firth@... (michael.firth@...)
Subject: Composite colour mod for Master 128

> -----Original Message-----
> From: 
> bbc-micro-bounces+michael.firth=bt.com@... 
> [mailto:bbc-micro-bounces+michael.firth=bt.com@...
> .uk] On Behalf Of bbc
> Sent: 12 March 2009 09:01
> To: bbc-micro@...
> Subject: [BBC-Micro] Composite colour mod for Master 128
> 
> Apologies if this has been covered before.
> 
> I found a doc that indicates how to do the composite colour 
> modification for a Master 128, which I want to complete. It 
> states 2 methods for 2 different issue boards.
> 
> Issue 1 Board - 470pF cap (assume a ceramic cap is okay) 
> across east leg of R137 and east leg of R153.
> Issue 2 Board - Link LK11
> 
> A few quick questions, I hope somebody may be able to help with.
> 
> a) what is the easiest way of working out which issue board I 
> have (I found some marking like "ISS.1", I'm guessing this 
> means Issue 1 board?
> b) The resistors cover the Rxxx markings, making it difficult 
> to locate the correct ones to solder to. I haven't been able 
> to locate a board layout diagram. Could someone point out 
> which are the two correct resistors to solder the cap across?
> c) *IF* I have an issue 2 board, where is LK11? I did a 
> manual search across the board, but I couldn't find it 
> (probably looking straight over it knowing my luck!!)
> 
> Thank you for the assistance.
> 
> Steve.
> 
There's a detailed explanation (with pictures) of how to do the Master colour
mod on Ian W's BeebMaster pages here:

http://www.beebmaster.co.uk/CompColour.html

I guess that R137 and R153 must be connecting on to the emitter of Q12 and
the base of Q13, which makes the mode effectively the same.

If your Master is issue one you won't have LK11, which is why you won't be
able to find it!

Regards

Michael