Asian Megadrive RGB problem!

[Rockard]

Yep, some time ago I build an rgbcable for my asian Megadrive 1, but I just got a blank picture!
I tried the cable on a friends uk Megadrive 1, and it worked perfectly!

Any ideas? Maybe the rgb not is connected int this machine?
Weird... I thought ALL megadrive1/genesis1models had rgb connected..

I do not have the machine handy right now, since I left it at home after moving,
I'll get it for the weekend.. but any help until then is appreciated!

[Vertigo]

I have an Asian one at home that I've not tried my RGB cable on yet but I'll check out for you tonight and post the results.
If it doesn't work I'll open the Asian and UK ones up and compare for differences, but I was pretty sure all model 1s supported RGB.
Is it possible this is like the two versions of the SNES RGB circuit?
You can see the differences between those here.

[Paper]

The PAL SNES outputs 12v so it can be used to autoswitch the tv to the av channel in 4:3. I don't see why an Asian Mega Drive one would have a similar difference.

Did you use your friends system and yours on the same tv set? If not, did you use the blanking pin (pin 16)? If not, then your friend his tv might recognise the RGB signals automatically, whereas your tv will not do so and needs to be switched manually.

[Vertigo]

Yes, you can add auto-switching to a Megadrive RGB SCART, mine has it.
By the way, I tried to test out to see if the cable worked on my Asian one, turns out my Asian one has decided to not work at all!  
So I'll add that to my list of stuff to fix.
Either that or I'll just replace the case of my normal one with the sexier Asian model so that the cart slot's universal without burning it and use this one for parts.

[Rockard]

Thanks for all the answers!

It is not a autoswtiching problem, I have checked all that stuff, and I have not made any obvious mistakes =).

Sorry about your asian megadrive, Vertigo.. =/
But thanks for the help anyway.

I am going to build a cable that I hopefully are going to use for both a modded pcengine and a medadrive. I'm probably going to try to route the audio to the 8-din instead of the jacket on the front!

It HAS to work... if now my stupid asian sega is fixable.. 2 days to go and I will give a report myself!
Wanna play my Contra Hard Corps and Castlevnia Bloodlines, that I just bought =).

[viletim!]

Rockard,
Crack it open and see if there's anything connected to the RGB output pins.

[Rockard]

I have now opened the megadrive, located the videochip, and found a datasheet for the CXA1145 chip. I have tested the connections to the videoport, and they ARE hooked up!

Weird! I guess I have to check out my cables and stuff again! =S
Maybe it WAS a switchingproblem after all.. uh..

OR, as the old cabel wasn't for me, I have to build a new one first.

I'll be back!

Now I am going to make a ntsc and regionswitch for it, until I start with the heavy stuff! =)

[Rockard]

Yes, of course, it was just me. I have no idea what went wrong the first time.

I have now routed the stereochannels directly to the 8din so I don't have to make a weird cable to have stereo(by taking the stereo from the front jacket).
I also rerouted some rgbwires from the board, and soldered the 75ohm resistors to the rgbpins _inside_ the console, so that I can use the same rgbcable with my soon-to-be-rgb-capable pc-eninge duo-rx =). Everything worked perfectly!

I find it highly unlikely someone is in the same situation as me right now, but anyway, here is the diagram for what I just did: (more job than making 2 cables? I don't care, I like making my own "ultimate" solutions! =P)

Original PCE connector (looking at console)
.x.....x
1...x...5
.2.....4
....3
1:Video
2:Audio Right
3:Ground
4:+5
5:Audio Left

Original Megadrive connector
.6.....8
1...7...5
.2.....4
.....3
1:Video
2:Green (reroute to Audio Right)
3:Ground
4:+5
5:Audio MONO (reroute till Audio Left)
6:Sync (screw sync!, reroute to Green)
7:Blue
8:Red

So both will now have these connectors in common:

.6.....8
1...7...5
.2.....4
.....3
1:Video
2:Audio Right
3:Ground
4:+5
5:Audio Left
6:Green
7:Blue
8:Red


=]

[Vertigo]

If you'd have just used the compsite sync pin as right audio you'd have only had to do one wire instead of removing then rewiring green, you odd person

[Rockard]

Ah yes, IF I was only going to use the cable for the megadrive, I could have done it that way. =)

But since I have to use the pce-connector as a base for the connections (I do not want to scratch the motherboard on the pce-rx, that board is so fragile), I have to rewire the megadrive to match the original pce-connections up.

Makes sence? =)

[Vertigo]

Ah, I see.
Well don't mind me then, good work
AFAIK you can also use this for Master System model 1 then, as that shares the same pinout as the Megadrive (iirc, which doesn't happen often)