mega drive (Y Pb Pr) or (VGA) mod ?

If you fixed screen jump just adjust the colors with pots, remember to put gbs to default and adjust rgb ,contrast ,brightness. if you find it difficult i suggest using 240p test suite for megadrive. You will need to burn it to eprom or cd depending on your configuration.

 

First, I want to change the resistor from 200K to 680K and that will be hard to find it in my country.
Secondly, I want to get another LM1881 for build good circuit.
Third, I thank you all.

 

One moe suggestion, if your megadrive scart cable is using pin 4 comp sync you may try rewiring it to pin 5 sync and remove lm1881.

 

It's true, i have Megadrive2 and i can link any pin i want, I use Pin 4 will try to use Pin 5 and remove the lm1881.

 

i wired pin 5 from my MD2 to GBS without LM1881 and the screen still jumping

 

your last bet would be trying syncstrike from arcadeforge.de

 

Just wanted to mention quickly - Sonic 2 is one of a few games which use the "hi-res" mode for the two-player split screen.

This is an interlaced mode, so must be causing issues with the scaler / converter?

Not sure why it doesn't support it though?
It could be that the sync voltage levels aren't quite right, but sounds like it's the converter itself?


OzOnE.

 

then something like this would work?

CSync Out ----------- 220 uF ------ 75 Ohms --------- CSync In

 

Difficult to say without testing with an Oscilloscope, but it's worth a try.

It looks more likely to be the converter itself which can't handle the slightly non-standard (I think?) Interlaced signal in the Sonic 2 two-player mode.

The normal / progressive modes seem to work OK, so you might need to find on the Web if other people have had success with the same converter on Sonic 2?

OzOnE.

 

my megatech to gbs works fine with or without lm1881 between and sonic2 works without problem. do you think measuring sync pin voltage on megatech would be helpful? i dont have megadrive2 but i'll try my megadrive1 soon.

 

Hi, @erhanpurple - do you (or anyone else) happen to have a Mega Drive / Genesis to Mega Tech adapter at all?

A friend has just sent me a MT board to repair, and he wants me to try getting MD carts to work on it too (if I can fix it).

It would be great if somebody with an MD-to-MT adapter could post a few photos of theirs.

Sorry for going OT there, but thought I'd ask.

OzOnE.

 

pm sent, its better to stay in topic