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3rd Strike graphical and sound issues on Net City cab

You are most likely sending Jamma level RGB (high-impedance input on the monitor chassis) through VGA level RGB (low-impedance on the chassis).
The results will be what you are experiencing on 3rd strike. White etc will be super blown out and look weird as hell.
 
A tri sync helper will fix this. Or you can change the input on the chassis to high impedance.
 
Gotcha, that makes sense. If I were to change the connection on the monitor chassis, would that need to be switched back when I hook up my CPS2 or MVS boards? Or could I in theory switch it and forget? If it's something that needs to be switched back and forth maybe the Jammafier is a good solve. But I'd love to make it work with what I have if possible
 
31khz games like Naomi will look super dim when connected to the high impedance connector. 15khz games like CPS2 and MVS should look great.
 
Had a spare MS2931 available.
This is most likely your chassis. You need T20 safety torx bit/screwdriver to get to it.
IMG_4449.jpeg


Vga cable should be connected here:
IMG_4445.jpeg


VGA is most likely connected to the low impedance input like this:
IMG_4446.jpeg


Change it to this for jamma. Hope it helps
IMG_4448.jpeg
 
Legend. Let me give that a try and report back. Sorry, how do I access it? I have a Japanese manual for new net city that I'm Google translating through but I don't see instructions for getting to the monitor chassis. Is it this back panel of the monitor I need to remove?

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Sadly not that easy. You first need to remove the front panel shroud.
4 screws in the front. 2 accessible from opening the control panel.

IMG_2902.jpeg


Then you need to unplug the speakers connectors since the speakers are fastened to the plastic back panel. Suck when you forget to unplug them… Take a guess on how I know…

IMG_2903.jpeg


And then you can unscrew the back. 3 screws on each side.
If your lucky, you don’t have to unscrew the ones marked with the blue arrows, but prepare to also do those if the back panel is stuck.

IMG_2904.jpeg
 
@Thomas did a great tread on his Net City restoration. Lots of great info here.
Thomas

Thread 'Sega Net City Restoration'

ネットシティSD（シットダウンタイプ）

IMG_5526.JPG


It's been a year and a half since I received a trio of Cities from KC and I'm finally getting work done on the third and final City, the Net City. I have always liked the look of the Naomi/Net City series of cabinets so it was at the top of my list when cabinet shopping. Plus I wanted one cabinet with JVS support. The tri-sync monitor is cool too. I specifically requested an Old Net City instead of a New Net City only because I prefer the orange stylings. I had no idea that the New Net City has a superior monitor.


Here's what I got...
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Got it! Thanks so much for the detailed info! Will try my luck with this and report back. Anything I should be careful of while I'm in there? I imagine I won't need to touch the CRT at all. Just hunting for one connector seems pretty straightforward so I'm not too worried about getting electrocuted or anything. Just being thorough..

Really appreciate all the replies on this post, you guys sure know your stuff!
 
Ok I got it open and I think I found the corresponding connectors. Mine looks slightly different from your photos but I think I'm looking at the same thing? The VGA is indeed connected how you said. The connector above it is red on mine and had a connector plugged into it but I'm not sure if it even runs to anything. There are definitely some random stray cables in the thing but I didn't see any other VGA or video related stuff in the bottom.

I popped out the potentially unused red connector and am about to replace it with the VGA. Seem right?
1000012663.jpg
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nem said:
The stock monitor in the Net City does 15khz natively, so I'm not sure I see the value of a Retro Scaler for this purpose.
Click to expand...

Would save him from having to disassemble a bunch of stuff everytime he wants to switch between 15/31K as his setup currently stands. Although I admit it is a bit of an expensive solution to the problem.

I suppose you could make a breakout for that 15K JST (?) to DE-15, then run two cables down where the PCBs would go and you wouldn't need any scalers/line doublers/etc in between. Or just switch to a Jammafier. But if everything else is working for him, I'd probably look into getting a breakout, then just run another cable and label them.
 
That's why you run the jamma video wires to the 15-pin AMP UP connector. Then you don't have to switch anything. There's two separate inputs. Now you're just using one connection.

I would also look into how the audio is wired. I've done a few Net City Jamma conversions and I wire the balanced amplified mono output straight to the speakers, bypassing the amp. It's the safest way to handle audio and works with every board.

See this post by twistedsymphony for more information:

twistedsymphony

Post in thread 'Help setting up a testbench!?!'

you'll want some 330ohm resistors inside of the SCART plug in line with the Red Green Blue and Sync wires because JAMMA outputs higher voltages than the SCART standard.
you'll also want to make sure you've hooked up video ground to pins 4, 5, 9, 13, 17, 18, 21

There are many different diagrams online for how to wire JAMMA to SCART. but I've personally found that 330ohm resistors, no capacitors, works best (at least on my display). I leave the 12V and 5V completely disconnected.

Audio is a whole other discussion
Essentially you're converting "Balanced Amplified Mono" to "Unbalanced Line...
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