megadrive (gennesis) 50/60 switch

[phreak97]

firstly, yes, i did the mod correctly..
its a pal megadrive, and when switched to 60hz, there is no colour..
anyone got any solutions?
i have tried on both pal and ntsc modes on my tv

[NFG]

Changing the mode of the system does not magically replace the colour encoding frequency to the chroma encoder, you'll usually need to install a new crystal for this purpose.  Normally PAL users have NTSC-capable TVs - or at least TVs that will run fine using PAL colour encoding in 60Hz.

Use an RGB cable and you'll be fine.

[phreak97]

ok.. i dont have an rgb compatable monitor at all anywhere..
i put in a new crystal.. its working now. and my tv does support ntsc.

[phreak97]

heres instructions, the guy said i could post them:

you will need:
Crystal (4.433619MHz for PAL or 3.579545MHz for NTSC)
50pF variable capacitor (trimmer)
15k resistor
30pF capacitor

and pasted from my AIM logs (looking at the CXA-1145 or CXA-1145P Chip) :
Now, using good RF construction practices (keep cables as short and direct as possible, and solder as much to the board as you can), solder one end of the 30pf cap to pin 5. Solder the other end to the crystal. Solder the other end of the crystal to pin 6. Then solder the resistor from ground (pin 1) to pin 5. Then the variable capacitor or fixed capacitor substitute from ground (pin 1) to pin 6.

check the resistance of pin 7 to ground with a multimeter.. if it's 0 ohms it is easyer to connect the variable capacitor between pins 6 and 7 than between pins 6 and 1. im not sure what condition the pin is normally in, as i already played around with it then linked it to pin 1 to put ground back to it afterwards.

after all that, play with the variable cap with something non-metallic until you get a clean picture.

done

note: i have no idea what happens if you put a 3.579545MHz crystal in a pal machine or a 4.433619MHz crystal in an ntsc machine.. it may work or may not.. try it yourself, the crystals seem common enough, i found two of the pal ones on a couple of old pcb's in my spare junk box, i wasnt looking for the ntsc ones.

this works in megadrive 1/gennesis 1.. the same colour problem occurs in the md2/genesis 2 but i cant say if the chip (the one closest to the av out on the md2/genesis2) is the same.. the pinout is similar, but it is made by fujitsu instead of sony, so the frequency required could be diff.. let me know if you try it.

lawrence, might you want to note this in the import mods section of gamesx?

[phreak97]

ok, so this is an old post, but whatever.
i have since learned a bit more about colour carriers and such, and the frequency for the fujitsu chip will either be the same, or a multiple of that number. i tried with the same, and it didnt work for me, but dont learn from my experience, as theres a good chance i made a mistake, the thing is stuffed from resoldering alot, if i ever work on it again, the pins will almost certainly break.

[simonbelmont2]

Here is the site with RGB cable: http://www.mmmonkey.co.uk/console/sega/ms-md-scart.htm
I was having your problem with no colour but now I have full screen, 60 speed, full color and quality image when I switch to NTSC.
Good luck!