NAOMI VGA (LOW RES SETTING) TO ARCADE STANDARD MONITOR

OldFoo · Post by **OldFoo** » Sat Sep 26, 2009 9:30 pm

As I mentioned before, the Naomi already outputs composite sync. There is no need to put wires together.

OldFoo · Post by **OldFoo** » Sun Sep 27, 2009 3:07 am

joshua3dg wrote:As I mentioned before, the Naomi already outputs composite sync. There is no need to put wires together.

Alright, but what the vga pinout number I must connect on the sync pin on the arcade monitor?

OldFoo · Post by **OldFoo** » Sun Sep 27, 2009 4:50 am

In 15k mode, pin 13 is composite sync. :smt045

OldFoo · Post by **OldFoo** » Sun Sep 27, 2009 2:37 pm

joshua3dg wrote:In 15k mode, pin 13 is composite sync. :smt045

Thank you so much!

I Will Try it!

Thanks again!

OldFoo · Post by **OldFoo** » Mon Sep 28, 2009 2:04 am

joshua3dg wrote:No, there is no need because the Naomi gives only one sync just like JAMMA games. The standard Naomi Jamma I/O has a DB15 connector which directs the 15k video signals to the Jamma edge without modification. All you need to do is flip dipswitch 1 to 'ON' and the games will automatically display on your standard monitor.

That's not true: the Naomi does output separate horizontal and vertical sync (unlike Atomiswave which only has csync) and the Jamma I/O board has a logic gate that combines H and V sync into composite sync. It also amplifies the RGB signals since the Naomi outputs 0.7vpp RGB which is not enough for an arcade monitor.

I managed to hook up the low res RGB from the DB15HD connector on the mobo to a scart TV by simply tying together the H and V sync. Not as appropriate as using a logic gate but it did work.

OldFoo · Post by **OldFoo** » Mon Sep 28, 2009 3:04 am

MKL wrote:That's not true: the Naomi does output separate horizontal and vertical sync (unlike Atomiswave which only has csync) and the Jamma I/O board has a logic gate that combines H and V sync into composite sync. It also amplifies the RGB signals since the Naomi outputs 0.7vpp RGB which is not enough for an arcade monitor.

I managed to hook up the low res RGB from the DB15HD connector on the mobo to a scart TV by simply tying together the H and V sync. Not as appropriate as using a logic gate but it did work.

I'm not sure of your source, but my information comes straight from the JVS Specifications manual. When using hi-res VGA mode, the Naomi outputs separate H and V sync signals; in low-res mode, the signal is outputted as composite sync, eliminating the need of another signal.

OldFoo · Post by **OldFoo** » Mon Sep 28, 2009 8:51 am

My information comes from examining and testing the hardware.

This is the video section of a Jamma I/O board:

The H and V sync signals from the VGA connector go to the 74F86 which combines them and then outputs a composite sync signal that is sent to the jamma edge. If the mobo already outputted composite sync in 15KHz mode there would be no need for this circuit. Also, when I made a scart cable for the low res RGB output (connecting the mobo directly to the TV), using just the H-sync pin or the V-sync pin didn't work and I had to tie them together to get the picture to sync.

OldFoo · Post by **OldFoo** » Mon Sep 28, 2009 9:14 am

MKL wrote:It also amplifies the RGB signals since the Naomi outputs 0.7vpp RGB which is not enough for an arcade monitor.

My Arcade monitor (Hantarex MTC9000) is EXTREMELY dim with the Naomi connected + Sega Jamma I/O..

I was actually thinking of amplifiying the RGB signals myself. Are you sure that the Sega I/O amplifies RGB going to the JAMMA interface...? If so, mine doesn't :smt012

OldFoo · Post by **OldFoo** » Mon Sep 28, 2009 9:26 am

Cageman wrote:Are you sure that the Sega I/O amplifies RGB going to the JAMMA interface...? If so, mine doesn't :smt012

Yes, I'm sure. You can see the three transistors that amplify the RGB signals in the pic I posted. I remember testing the 15KHz RGB on my Aero City and it was OK. Maybe you need to fiddle with the RGB gain pots on your monitor?

OldFoo · Post by **OldFoo** » Mon Sep 28, 2009 9:36 am

Hmm... ok..

Yeah, I tried fiddling around with them, but the monitor is set up perfectly for JAMMA PCBs. MVS also runs fine. It is only with the NAOMI that the picture becomes dim.. So I actually do not want to constantly change the RGB gains when swapping systems..