Naomi 2 Screen problem

OldFoo · Post by **OldFoo** » Fri Dec 21, 2007 6:11 pm

Hi There,

Would any of you have any idea what has happened to the display on my Naomi Cab.

This has just happened and I dont know what has caused it. It has to be the Naomi board because I can connect a dreamcast up to it and the image is fine.

Any help would be gratefully recieved.

J.

OldFoo · Post by **OldFoo** » Fri Dec 21, 2007 7:01 pm

You got another Naomi mainboard to try?? looks like something has gone on the RGB to give it over bleed/contrast.

OldFoo · Post by **OldFoo** » Fri Dec 21, 2007 7:25 pm

I dont have another mainboard. I have tried it with a GD rom an I get the same results. Really dont know what has caused it?

OldFoo · Post by **OldFoo** » Fri Dec 21, 2007 8:49 pm

could be a monitor fault,i have had a hantarex do the exact of this but i guess your monitor is a sanwa 31k and i have never seen this fault on a sanwa

if you have a pc try plugging it onto the monitor to see if the overdrive effect goes-that will prove monitor or mobo

OldFoo · Post by **OldFoo** » Sun Dec 23, 2007 5:54 am

I've seen this happen on two Naomi mobos (actually one was a Hikaru). Take the mobo apart and look at the backside of the connector board. Look closely at the traces that go to the back of the VGA port and you will probably see some burn marks. Use a multimeter to trace each pin of the VGA port back to the joining capacitor to confirm which trace is burnt/broken.

I don't know how it happens, but since I've seen it twice I guess its common. I just soldered a very thin red wire from the vga pin to the cap solder point (on the front side), and it cleared it up.

OldFoo · Post by **OldFoo** » Sun Dec 23, 2007 8:25 pm

I have taken it apart and it looks like your diagnosis was spot-on. One of the traces coming from the vga port looks burnt out. Would you be able to send me a photo of your repair So I have a clearer idea of what I need to do.

Happy xmas everyone. :smt114

OldFoo · Post by **OldFoo** » Mon Dec 24, 2007 1:30 am

Here are some pics of the Hikaru (sorry I couldn't find which Naomi mobo I did it on). The filter board on the front is generally the same as Naomi.

So, what you want to do is reconnect that burnt trace to the coupling cap. So I soldered one wire to the back of the vga port pin that was burned and then ran it to the coupling capacitor, but had to do this on the other side (front side) since you can't on the parts side (back side). You may have to drill a little hole to send the wire though, the Hikaru pictured here already had a hole I conveniently used.

Using a mulitmeter (or just count number of pins over) you should be able to see which coupling cap solder point on the front side connects to that burned out trace on the back.

Sorry for the close-up tight shot, I didn't want to disassemble my planet harriers just for this. The solder point on the Hikaru is just below the vga port. On the Naomi its the line of solder points just above it.

OldFoo · Post by **OldFoo** » Mon Dec 24, 2007 10:40 am

Dave, you got a Hikaru.. Nice..

Be careful with those boards, very tempermental! I got some brand new ones here, and I regular keep in touch with Ken on the Hikaru status.

I just did a Brave Fire Fighters youtube video, probably the most awesome Hikaru game, the flame effects are breahtaking!!

http://uk.youtube.com/watch?v=EKOmIBPI1iE

OldFoo · Post by **OldFoo** » Mon Dec 24, 2007 5:55 pm

Sorry to keep going on about this. I am desperate to get it fixed.

I have posted a few more shots of my board. The first is the damaged trace. This is above and on the reverse of the vga port.

The second is the back of the board.

And the third is the front.

I know you said my board would be different to yours but I am starting to think that the damage I have done to mine isnt the same. I.e. The damage isnt on the reverse of the vga port it is above it. Hope that makes sense. Any help would be good.

OldFoo · Post by **OldFoo** » Mon Dec 24, 2007 6:52 pm

If it was me, I would find out which contact this burnt lead is supposed to go to and run a small wire from the solder joint of the white connector (from the front side) straight to the blue surface mount capacitor(?) that the trace goes to. Looking at it up close, the blue 'covering' goes near flush to the pcb, so this might be difficult to do, if it can be done at all.

The only other options I can see that are available would be:

1)Get a new filter board (the pcb you are holding in the pic)

2)Get a new/another Naomi (to replace current board; non-working system for parts)

3)Send it for repair. (www.irepairsega.com -- Ken Westerfield is awesome!)

I'd say #2 is the fastest, most available option. Getting a non-working Naomi for the filter pcb wouldn't be hard.