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Possible bad Genesis mod?

Started by madmalkav, February 04, 2004, 06:49:52 AM

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Ok. I modded my genesis with the region and 50/60hz switch. When I put it to 60hz in my european tv, I get black and white image, but it's not stable, the image flicks and move and does extrange things. With my other mods/original ntsc systems I get black and white image, but it's stable. So I want to know if I did something wrong so I can correct it before I test the rgb cable I'm ading and think it's cable failure.

Thanks a lot.


The Genesis models aren't all the same, some of them have a single point that controls both 50/60Hz as well as the PAL/NTSC colour encoding, some have two points.  It sounds like your TV is syncing to the 60Hz but is choking on the colour data (which seems to be NTSC,  not PAL).  The datasheet for the Sony encoder is on somewhere, you want to check the NTSC/PAL pin.


Ok, so in the CXA1145 -shit, I was sure it was 1135- I have to send +5V to pin7 for NTSC and ground for PAL. Just two silly questions:

(Just curiosity question)
What is the part of the console determining if the system works 50/60hz?

(I'm fucked question)
I made the RGB cable. It won't work. Only display green channel, and still the choking. The thing is, I tested continuity in all the connectors and the cable give the correct measures... it's really odd.

Thanks again for all your help.


Make sure you haven't got the pinout reversed right to left, that'll cause some trouble I assure you!

There's a pin on one of the chips that determines 50/60Hz, but there's quite a few revisions of the system, so it's hard to say which chip and which pin.  Part numbers changed a lot...  You can try tracing the point back from where you adjusted the voltage and see where it goes.  Use your multimeter's continuity check and drag the second probe across the legs of the chips until you find it.  


I was already warned about the pimout thing. It's a X File.

UPDATE: I soldered pin 7 to ground to made it output pal color always, but seems like system just ignore my mod. Will continue investigating, more news as soon as I get some time.


Connecting pin 7 to ground is correct but the color subcarrier frequency
changes when you switch between 50/60hz.

You have to lift pin 6 (I think?) and insert a 4.43 Mhz clock signal for
PAL tv's or a 3.58 Mhz for NTSC tv's.


Thanks for your reply.

From the component manual:

PIN 6 -> XO IN.

For external oscillation, input to pin 6 through a coupling capacitor.

My question is, can I get the 4.43mhz signal from anywhere in the system or I have to use and external component? In that case, what component? What they refer to coupling capacitor?

Sorry for this basic questions, I'm a total nerd in electronics, and having all the docs in a foreign language don't help.



Wow, yeah, will try it as soon as I can go to the electronics parts shop.

The only think I dunno what is is that marked as "30".

Thanks a lot for your help.


the 30 thing is a type of capacitor, i think
Why are you reading this?


there is a MUICH easier mod you can do for a 50/60hz switch..........i can give you the link if you really want.  it only requires a SPDT switch and a simple trace cut and solder job.  took me under half an hour to do.



As I state in the first post in this thread, I already did that. This is aditional work for pal TVs that dislikes ntsc colour enconding.


i belief the 30 thing is a 30farod ceramic capaciter, should be available from maplin, rs components, farnell etc or ( outside of the uk )

there are probably other online sites that are available. for people in germany


QuoteAs I state in the first post in this thread, I already did that. This is aditional work for pal TVs that dislikes ntsc colour enconding.
No offence but woulden't hooking the MD up via RGB sold the entire PAL / NTSC colour encoding mallarky?
Formerly 'butter_pat_head'


the RGB cable will solve the black and white problem, i have built and tested the cable, unfortunatley my mega drive has broken :( but the cable scheme works 100% the picture looks so much better than the dodgy RF Unit you normally get..

here are a few schematics for RGB cables for MD an RGB mod for SMS