Removing jail bars from Sega Nomad?

[xga]

Hi Guys,

I successfully removed the jail bars from my VA4 Mega Drive by lifting pin 50 (SBCR - Sub carrier output) from the VDP IC (315-5313). My understanding of this modification is that the SBCR creates interefence to the RGB signal and by lifting pin 50, it stops the interference / jail bar effect.

I quite often use the RGB output of my Nomad connected to a RGB monitor. The Nomad also suffers from prominent jail bars, so I'm keen to perform a similar modification to remove the jail bar effect and improve the visual quality.

My Nomad has a 315-5700 VDP IC which I understand is the same as a 315-5660 IC. Looking at the 315-5660 IC datasheet, I see that the SBCR is on pin 131. If I lift this pin, will this also have the same effect of removing the jail bar effect on the Nomad?

I've done a bit of searching and I haven't been able to find anyone that has experimented with removing jail bars on a Nomad before, so I'm hoping that I can get some advice / recommendations from someone here.

Thanks in advance!

[nem]

Considering you have done most of the work, you should just go all the way with the mod and report back.

[leonk]

My understanding is that by lifting pin 50 you're basically killing composite video (you'll only get black and white). This might not be a good idea for NOMAD if you plan to ever do the LCD screen mod. The LCD mod uses composite video (connected internally).

I've never noticed jailbars on any sega genesis console connect via RGB on my Sony PVM. I use the following SCART cable:

http://www.ebay.com/itm/161575853221?_t ... EBIDX%3AIT

The solution here is to boost the CSYNC signal (which is lower than RGB levels in Genesis) rather than neuter composite video.

[Fudoh]

instead of killing the sub carrier you can bypass the blue channel. Just cut the trace on the board (as close to the VDP as you can) and connect a wire from the VDP's blue output to your encoder's blue input instead.