PAL Video Modification  -  Brian Parker
               ---------------------------------------

ED. NOTE: We have to make the normal disclaimer about this piece - ie, if
you decide to do the modification mentioned, you do so at your own risk,
and we can't be held responsible for any unforeseen glitches. All due care
has been taken in the description, however, and it works!

         For further information about this topic, have a look at the
"ExpanBlues2" article on this disk.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


       This article describes a hardware modification to version 1.3 Amigas
(which have a PAL AGNUS chip but NTSC composite video circuitry) which will
give full PAL composite video. This is most useful for recording the Amiga
output on video, since the output when you dump to video from a 1.3 machine
is black and white.

PARTS LIST- 33pF, 56pF, 10pF and two 220pF ceramic capacitors.
            .001uF greencap.
            9.8-60pF trimmer capacitor (or anything around 30pF).
            47K 1/4 watt resistor.
            4.433619 MHz PAL xtal.
            (optionally, a 28.37516 MHz oscillator from a Commodore repair
            centre).

PROCEDURE-
       Disassemble the machine. Locate the MC1377 chip at the top left corner
(looking from the front). Cut the tracks leading to pins 1 and 17 on the
underside of the board, and disconnect pin 20 from earth by cutting the
tracks on the component side of the board. (N.B. It is connected to earth on
both the inside and outside of the pin. Cut the inner track by levering a
small screwdriver across it several times).
       Replace C45 with the 33pF ceramic, and replace C54 with the 56pF.
       Now connect the other components as follows-
1)     A 220 pF across pins 17 & 18.
2)     A 220 pF    "     "  15 & 18.
3)     A 47K resistor across pins 1 & 16.
4)     A .001 uF greencap from pin 1 to the adjacent earth plane.
5)     Solder the 10 pF ceramic across the trimmer capacitor then solder one
       end of the trimmer to pin 15.
6)     Solder the crystal from pin 17 to the other end of the trimmer.
7)     Solder a wire from the can of the xtal to a nearby earth.

       When doing the above, try to keep the component lead lengths as short
as possible. If you are not into free-form modern sculpture, you could
probably desolder the MC1377 and mount the whole lot on a bit of vero board,
with connections to the original IC position.
       Once this is completed, partially reassemble the machine- leaving the
top shield off. Turn it on, connected via a suitable cable to the composite
input of your monitor. Let the machine warm up, then adjust the trimmer until
the interference lines (seen most prominently at the border of orange and
blue) are stationary and minimized. Then complete reassembly.
       One last modification is needed to bring the machine up to full PAL
standard. This is to replace the main oscillator with a 28.37516 MHz version.
As this is only 1% different to the NTSC clock, it would probably only need
to be changed if something like genlock was used.


~~~~~~~~~~~~~~~~~~~~~~~~~~~ END OF PAL1.3TO1.4.mod ~~~~~~~~~~~~~~~~~~~~~~~~