PAL MegaDrive 2 after modding...

Started by DarkGlider, March 19, 2004, 11:46:58 PM

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I was wondering if there is any way of getting colour with the 60hz image without buying a SCART lead and a TV that has SCART input


In NTSC colour encoding mode the CXA1145 has pin 7 connected to +5v, and in PAL mode it's grounded.

Also, between 5 + 6 there's a clock crystal, 3.579545 for NTSC, 4.433619 for PAL.

Change those two things and you'll change the output; 50 or 60Hz is determined by the import jumper settings.

There's a catch tho, sometimes (but not always) the jumper that sets 50/60Hz is also connected to the CXA1145, so if you want to set PAL encoding, 60Hz make sure you can change these individually.  Cut and lift the leg on the encoder, or follow the trace and cut it somewhere on the PCB.

dum dum

when i got my japanese MD2 it was modified to give 60Hz pal (and retain the J setting) and it did have a 4.43MHz crystal added just like you have mentioned. so whats the point of me saying that? well that machine had a sony encoder in it.. I am in a pal country and all the pal MD2's i have opened have a fujitsu encoder and for some reason i have not been able to get this to work on them.

i can only conclude that the fujitsu chip is more fussy on what can be fed into its subcarrier pins (a simple crystal with or without the resistor/capacitor filter recommended by product spec. documents doesnt seem to do it).

so if you have a non sony encoder, it might not work with out some tinkering. or maybe  im always doing something wrong? anybody else had experience with non sony chips?

oh yeah, the resistor/capacitor filter as recommended by some spec. sheets can be found next to the encoder - my sony mod unit bypasses it and it seems to work well, expect certain conditions can bring on random colours which may or maynot be related to it (i'll have to verify this one day to makes sure its not just a dodgy system)   eg: sonic3d animated sega logo gets random colour at top half of screen as it zooms in.


Quoteall the pal MD2's i have opened have a fujitsu encoder
Interesting.  The WonderMega (And X'eye) systems use Fuji encoders as well.  The Fuji part is pin compatible with the CXA1645, a newer unit than the CXA1145.  It uses a different clock input than the NTSC MD2, so you won't be able to use the same clock...