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Sega Mega Drive 60Hz colour fix - Completed!! Need a little help with a MD2


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Hi everyone,

 

Well I got my hands on some crystal oscillators from Hy-Q in Melbourne and decided to do the crystal colour correction mod on my Mega Drive 1.

Thanks to MangledLeg's excellent blog entry (and quite funny also :lol) I was able to pull this off no sweat. I just changed the design a little and grabbed ground and 5v right near the resistor that I needed to feed the cyrstal to (Sorry Mangledleg:) ). The picture is perfect in 60Hz and VIA S-Video looks pretty damn good.

Anyway I am planning on doing it to a couple of MD2's I have here. Just need some advice. Hewitson mentioned that I can feed the signal directly into the pin 6 of the MB3514 chip. This of course is after i cut the trace that runs from pin 6.

 

Is that all that is needed?

Thanks everyone!

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Thanks for the props mamejay, glad you enjoyed the tute :) No worries with where you pulled the +5v/GND, in the mods I've done since then I've grabbed them from other spots as well, it's whatever's easiest to grab, and the shorter the lines, the better. I'm actually planning on making one amendment to the tute, and that is to install a switch to select either the new 4.43mhz oscillator or the original signal. Reason being is that when outputting via RGB, the colours randomly flicker between normal and washed-out. I thought it might have been my Mega Drive, but I have another here with the same mod, same problem. Installed the switch, works fine now regardless of which video output I'm using. There'll be updates to the blog once I've written it.

 

RE the MD2, I'll have a tute up on that one in a couple of weeks hopefully, but Hewitson's theory sounds about right - I was doing some research on it myself since I'm planning on doing an ultra-mod to a SMD2 I have around the place (RCA composite AV, S-Video, 50/60hz, Eng/JP language, cart slot fix for imports, colour mod w/switch, 12mhz or 10mhz/original mhz selectable overclock with halt switch, not doing the crystal audio mod though, that's insane!), and found that colour mods using the DIY oscillator method are currently being discussed elsewhere:

 

http://www.sega-16.com/forum/showpost.php?p=299828&postcount=38

 

In this case, TmEE (who pioneered the crystal audio mod IIRC) has suggested something similar to my mod on the SMD2 - found the clock before it passes through the relevant resistors prior to getting to the encoder, cuts the old signal and insert the new clock with an all-in-one oscillator, alla the MD1 colour mod. Alternatively, you can disconnect the whole line from pin 6 and feed the clock directly into the chip from the oscillator, though I'm not sure if you need the resistors in-line to make the clock signal happy for the encoder. Your call - I'll give both a shot when I mod the SMD2 if TmEE's method doesn't work. I had a look at the datasheet on the MD2's encoder, but couldn't decipher what needs to be done to the clock signal prior to feeding it to the IC; managed to get that much out of the datasheet on the CXA1145 funnily enough, and was pointed in the right direction by viletim! at NFG when putting together my original colour mod.

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I have one more MD1 here which I will do the majority of the mods on excluding the crystal switch and overclock switch. Region, 50.60Hz and colour mod will be done. Will have that one for sale here.

 

I have 3xMD2's will hack one up and do some testing for the colour correction. Should be done this weekend. Will let you know the results.

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Damn I like the sound of the 'ultra-mod'.

 

Yeah, should be fun :) Found an electronics outfit in Australia that have canned 12mhz and 10mhz crystal oscillators I can order online, so might order some so I can get cracking next weekend; if MJ sorts out the colour business on the SMD2, that'll be interesting as well and will save me some trouble!

 

I have one more MD1 here which I will do the majority of the mods on excluding the crystal switch and overclock switch. Region, 50.60Hz and colour mod will be done. Will have that one for sale here.

 

Sounds good. I tried selling off a similar SMD1 on eBay a few years back, but didn't get a lot for it as I don't think anyone appreciated how special the colour correction mod was, and my listings kept getting taken down because I couldn't list that it was a multi-region console. I'm sure you'll have a better chance on here of sorting something out :)

 

I have 3xMD2's will hack one up and do some testing for the colour correction. Should be done this weekend. Will let you know the results.

 

Awesome mate, let me know how you go with the colour correction, otherwise I'll just give it a go next weekend and see what happens ;) I'm a bit behind on my tutes anyways, so bugger knows how long in reality it would take to write it up and post it online ;) I still have the RCA >> Stereo + S-Video converter box for the C64/CBM monitors one to do, and add the colour mod selector switch tute as well. Been meaning to get some tactile switches off eBay I think you pointed out to me a while back and mod the A2600 joystick I have and write up a tute on that one as well!

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Hi Mangled,

 

you inspired me. I have started the ultimate MD2 console.

So far we have widened cart slot, 50/60Hz switch, Jap/Eng switch, AV and S-Video outputs and a bright blue LED.

I am testing feeding the crystal oscillator into the pin 6 of the MB3514 and am getting a weird result. I now have colour but the sega symbol is red. All blues and blacks have a reddish hue. If i flick back to 50 hz the screen just scrolls now. I have tried direct on pin 6 and also on the other side of C24. This is after I cut the track to C24.

I will keep playiny. Let me know what results you come up with.

 

---------- Post added at 08:43 PM ---------- Previous post was at 08:13 PM ----------

 

SUCCESS!!! You need to feed the signal in before resistor R61. Also need to cut the trace to R61.

 

http://www.fileden.com/files/2008/4/21/1876835//MD2fujitsuClock.jpg

This is not my console. Found it on Sega-16.com forum.

 

Now to seal it up and admire the mod work.

Edited by mamejay
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Awesome, I thought you'd have to massage the signal to get it ready for the IC (you have to do the same thing with the SMD1 mod) :D

 

BTW, that's TmEE's work, I referred to him and that post in one of my replies above with the URL to the actual post where he offered the picture. Annoyingly, everyone seems to have ignored it on that forum, so I'll give him props as well when I write up the tute. That was going to be the method I was going to use on my machine too, so you've saved me the trouble-shooting job!

 

Very chuffed to hear I inspired your work too :D In turn, huge thanks for testing this one - I'll give you credit when I write my tute up as well if you like, I think it's only fitting :)

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Funny you should say that. I joined that Forum and thanked TmEE on the thread and said it was so easy and for everyone to follow where he fed the signal into.

That is true everyone is fucking around adjusting shit and testing where TmEE told everyone exactly what to do.

 

Its all good bro about giving me props for the testing. If I didn't do it I am sure that I would have been reading your blog next week anyway and leeching the way you did it ;)

 

The console is complete now. The blue LED is so bright and looks awesome.

 

Will be putting it up for sale shortly on AA for someone to enjoy the fruits of my research and labor.

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not doing the crystal audio mod though, that's insane!

Bummer. :)

 

I want to do an MD audio mod bad, but don't have the guts to attempt one. I really wish someone would knock together a pre-made PCB so mooks like me could do it easily.

 

I've heard the before and after comparisons, and it's night and day (particularly on the MD2, which had shithouse audio hardware).

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  • 5 months later...

Bump!

 

Just wanted to point out that I've added a supplementary tute on my blog for adding a switch to roll between the original signal and the external oscillator:

 

http://www.retro-otaku.com/2011/04/adding-a-switch-to-the-60hz-colour-mod/

 

If you need the original source, here 'tis:

 

http://www.retro-otaku.com/2010/07/pal-sega-mega-drive-colour-correction-60hz-in-full-colour-in-rf-composite-and-s-video/

 

The original tute has also been updated to recommend the switch method if you're going to use RGB in the future.

 

Next on the list is to write some tutes for all the stuff I did to that SMD2 last year. That'll be a big series of posts, shame I'm lazy and take forever to write up tutes ;)

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