Date   : Fri, 08 Feb 2002 22:31:54 GMT
From   : pete@... (Pete Turnbull)
Subject: Re: Master Compact Service Manual

On Feb 8,  8:19, Chris Richardson wrote:
> Hi all
> Does anyone have, or have access to, or know where there is a copy of the
> Master Compact Service Manual? It would be very handy to have a scan of
> this.
>
> Gerry Rigby wants to know what chips are required for the RS232 upgrade
for
> the Compact.

I have one.  I might be persuaded to lend it to some responsible party for
scanning, but I'd need to be sure I got it back safely.

To answer the specific serial port question:

I used to do this quite a lot (used to run one of Acorn's Service Centres).
 It's quite easy, no soldering.  BTW, all the Service Manual says about it
is "The serial interface is not fitted as standard.  The modification to
fit the serial interface only requires the insertion of the relevant ICs
into their sockets."  That's it!

Parts required:

IC5  MAX232
IC9  74ALS169
IC13 Serial Processor (same as used on late-model BBC B and Master 128)
     Acorn Part No. 0201,648
IC14 6850 ACIA

Ensure power is OFF.  Fit the four ICs in the appropriate sockets.  Turn
power on.  Test the voltage at TP1, it should be between -10 and -8 volts.
 The value is not critical, but if it deviates much from that, there may be
a fault.  Test the voltage at TP2, it should be between +8 and +10 volts.
 The value is not critical, but if it deviates much from that, there may be
a fault.

-- 
Pete                                           Peter Turnbull
                                               Network Manager
                                               University of York