sega naomi display issue

[Arcnewb]

This is a Crazy Taxi sit down cab, I bought from the local skating rink. The owner said she wasnt sure what went wrong with it, but it used to play. Only paid $250 for it.
I am not sure if i have a monitor problem or its the Naomi itself. When I plug the Naomi into a VGA monitor, tried 2 different ones, lcd vga monitors, I get almost the same result. With the dell I get for a brief second the Naomi logo then black screen and a message on monitor saying no signal, entering power saving mode, the other el cheapo walmart special, no signal, then black.
the Naomi is on 31 signal, tried both ways, with on 15, no naomi logo on dell, just no signal on both monitors.

now, when I hook the arcade up to my laptop, i get a clear display after tinkering with the pots on the monitor, and messing with the resolutions i do get varying results, the shot in the video link below is the best i got it. the screen is doubled, but clear. and the second video is with the monitor hooked up to the naomi. Any help would be appreciated, I don't see any leaking caps, or any corrosion looking at the board. I haven't taken the monitor out, because I havnt really figured out how to yet, I think It has to come out from the front.

https://www.youtube.com/watch?v=R6xcUlsuc4Y

https://www.youtube.com/watch?v=cQeL6dF1oBQ

 

[aramis1]

Try the naomi without a cartridge first, they're easier to troubleshoot that way since the carts can go bad. It should sit at the splash screen and you should be able to go into the test mode. I've seen a lot of dead Naomi motherboards, usually they don't boot at all or boot but run wonky/super slow. 5V too high can kill the motherboards and carts, so check the voltage on your machine and set it right at 5V.

Newer LCDs I've found often don't work with the naomi hi res mode and definitely will not work in standard res. Naomi runs @ 800x608 I think, and usually an older monitor or TV is needed. I've had better luck with older TVs with "VGA" input. Go to a goodwill or something and grab an older square monitor with VGA output only it'll work.

I think you're problem might be sync related on the monitor though. Check to see if your sync wire is working properly, try a different cable maybe. I don't know if the video signal first goes to the I/O board, if so try hooking the naomi directly to the monitor.

The laptop is probably outputting too high of a resolution, that's why it's doubled.

 

[aramis1]

yeah looking at the video make sure the sync connection is good to the monitor and adjust the pots (if it has them) for the sync if you haven't tried already. After that check the header/connector into the monitor.

The LCDs you are trying probably don't like the naomi signal that's why they are showing it a sec and shutting off.

One more thing make sure if your monitor is a dual/tri res that it's set for the proper input.

 

[Arcnewb]

i was able to get it into test with the buttons, gona pull it back out tomorrow and try with the game board popped out and see what happens.

I did try a new VGA cable going directly from the Naomi to the monitor with same results, its kind of hard to see whats wired to what the way they shoved everything under the peddle board on this cab, but it does appear that the VGA cable goes directly to the monitor.

What exactly is the sync cable you are referring to?
I have tried adjusting every pot on the monitor, and the remote board, also when the remote board is unplugged the monitor goes into a vertical collapse.

I appreciate the replies, and hope i can locate an old vga monitor so i can rule out the Naomi itself or the monitor.

The dell auto detects the signal, and was correct on VGA, the el cheapo i manually selected VGA, but, they are both from this time era.

any more suggestions, send this way!!!!

 

[Arcnewb]

tried running the Naomi without the game installed, had same result.

so, what i did was took the little vga adapter out, and took some bread board jumpers and made all 6 connections from the vga cord to the header on the monitor board manually with the jumpers. when i disconnected the vertical sync jumper i had no change at all. Header looks good, but i haven't removed the chassi so i cant see the solder connections on the bottom portion.

So I am assuming this is a monitor issue.

I think it is a nanao 05B20085D1, any ideas on the faulty part?

 

[aramis1]

Make sure you're hooking up the sync to the correct pin, that monitor probably has multiple sync pins (I'm not a crt expert, but I've sat there scratching my head over a monitor that wouldn't sync to find I was on the wrong sync pin). So try them all. I think that's a nanao 2932 so you can download the manual online I'm sure.

Other than that I'd flex the header pin, it might have a cracked solder joint which isn't allowing it to connect. Worth it to pull the chassis and re-flow the header and inspect for any bad components anyway.

 

[aramis1]

Also might as well check the sync pots on the control board and spray some deoxit on them and reflow them.

 

[Arcnewb]

Ill try that, and try other pins to see if i have the sync pin correct, altho Im pretty sure i got it right, the picture is exactly the same as when hooked up normal. I am also going to try the same with projecting my laptop screen onto the monitor and see if it makes a dif, could be the sync pin on the naomi itself. it was late last night and didn't think about trying that either

Thanks again!

 

[Nemesis]

The Naomi has a common issue where a "supercap" on the board leaks, which can cause damage. It'd be worthwhile checking out if that's an issue here before you run power through it too many more times. In my experience, you should just be able to plug the naomi directly into any standard PC monitor and get an image. It sounds to me like you've got a faulty board.

 

[Spunky_Bruiser]

I would check that cap mentioned above. i believe it is cap 29. c'te bastard 29... I just refurbished 3 for my friend. On one of hem cap 29 blew up and leaked. The net dim above it took the bulk of the explosion.

In the picture that is cap 29, id you see D1 under it, it is corroded, and a little more around it. This is very mild compared to some others I have seen. The net dim took most of the damage though.

 

[Arcnewb]

Thanks for the advice, ill be checking that out next!

 

[Arcnewb]

Figured it out. I took the Naomi apart and found a burnt trace from the vga jack to a long pin connector. Had to de solder and remove the connector to see the path,and resolder. Installed a jumper wire on the trace and now she is running perfect!

Thanks for all the tips

 

[Hydreigon]

Figured it out. I took the Naomi apart and found a burnt trace from the vga jack to a long pin connector. Had to de solder and remove the connector to see the path,and resolder. Installed a jumper wire on the trace and now she is running perfect!

Thanks for all the tips

You learn something new every day. This should be recorded to a Naomi repair log of some sort.

 

[irepairsega]

Naomi 1 / 2 Video Ground issue.

I was just going to recommend verifying the video ground trace but then I noticed there was more to the thread. No the super cap would not cause this issue. Just replied to two newer threads regarding this same issue. Super common thing to have this video ground trace pop. If you take 5 or 12vdc and touch it to field ground in cab, it will instantly pop this trace. So, somewhere at some time, most likely 5vdc touched field ground and caused this. Usually its the coin coor light wiring shorting across top of coin box or maybe pinched in coin mech. regarless, you need to go over anywhere 5 or 12 can touch metal in cab. Once that is figured out, jump burnt trace with a .5amp fuse. Do not run a solid jumper wire or if short happens again, you will nuke video out circuit. I have a paper I wrote up on this. If you email me I can send it to you.