Re: Modifying SX-64 from NTSC to PAL

From: Nicolas Welte (
Date: 2001-05-03 11:00:54

Marko Mäkelä wrote:
> > So it gets more complicated than a normal C64...
> As I don't have an SX-64 or the schematics for this subboard, I'm passing
> a copy of this message to the cbm-hackers mailing list.  If there are no
> PAL SX-64 owners on the list who could help you, you could try to
> construct some sort of a schematic diagram for the subboard (even just the
> part numbers would help a lot).

I have both a PAL and NTSC SX-64, and I think that just the two crystals on
the sub-board have to be swapped, because there is a dedicated crystal for
both color and dot clock. The problem will be to get a matching dot clock
crystal for the PAL mode, because it is something like 7.88MHz. This is much
harder to get than the color clock crystal with 17.734 MHz, which also is not
that easy to get. I would rather build a new oscillator sub-board from
scratch, based on the C64B clock circuit that needs just the 8701 chip and a
single (color clock) crystal.

The other problem is the built-in display: It also is a different version and
will not display color if you convert the C64 board to PAL. From what I've
seen both displays use the same boards, but the NTSC board lacks some
components, but other components will probably be of a different type. I do
have a very bad copy of the PAL CRT schematics, but none of the NTSC type.
Converting the display as well is not an option I fear.

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