'Rolling' Screen Issue & Colour Problems [FIXED!]

[BareKnuckleRoo]

I just got a Net City - it's having Vertical Sync/Hold issues where the screen rolls like crazy. I'm testing this out with a Futari PCB if this matters, messed around with the settings to no avail. This is what I'm getting:

http://i.imgur.com/t5oXo9b.jpg

Another oddity - the volume knob within the control panel doesn't seem to be adjusting the game volume. Would a volume control be located elsewhere?

[nem]

Net Cities aren't wired for jamma originally. You have an aftermarket or homemade harness installed in it. The volume control in the control panel controls the amp that's inside the cabinet. Your jamma harness is most likely wired straight from the PCB to the speakers. There's a small potentiometer on your Futari PCB to control the volume.

As for the picture, you will have to take off the back cover and try to adjust the vertical hold manually. There's a line of pots on the side of the monitor chassis.

[BareKnuckleRoo]

The seller put a JAMMA harness in it for me. It was originally wired for some shitty ass multigame thing.

Discovered what was wrong with it: there's an orange capacitor that fell clean off the board and is just rolling around in the monitor casing. What kind of capacitor is supposed to go in this spot here? The capacitor is so dirty I can't make out any markings on it.

http://i.imgur.com/lWDa9OT.jpg

[BareKnuckleRoo]

If anyone can ID this capacitor and what I need to buy to replace it, that'd be super. I can sort of make out 6.8 uF?

http://i.imgur.com/MkdhyOF.jpg
http://i.imgur.com/iF0wdyc.jpg

[xga]

C702 is a KXB 250V 6.8μF, 105°C capacitor made by Nippon Chemi-Con. It is high ripple current capable and is 18mm in diameter and 40mm tall. The KXB range of capacitors are no longer made by Nippon Chemi-Con, so the next best alternative would be from their KXG range.

Or you could just use a good equivalent from someone else. e.g. Rubycon, Panasonic, Nichicon etc.

Hope that helps!

[BareKnuckleRoo]

That's perfect, exactly what I needed, thank you very much!

[BareKnuckleRoo]

Okay, so after some serious fussing with the metal underside of this, there's a brand new capacitor in. The screen appears to continue to be 'rolling' (I've doublechecked the capacitor's fine, polarity's correct, etc). Any other ideas of possible suspects, short of going through and testing each component on the board?

[xga]

Do you have any other JAMMA boards that you can test on it?

I'd be interested to know if you are having this sync issue at other frequencies / resolutions e.g. 24kHz or 31kHz

Do you have a way of testing a source through the VGA input on the chassis? Perhaps a Dreamcast with a VGA cable or a MAME PC with Soft15kHz or CRT_EMUDRIVER? Do not put anything higher than 31kHz / 640x480 through the VGA input otherwise you run the risk of killing the sync circuit.

Perhaps have a look at the sync troubleshooting section on page V-5 of the service manual - http://wiki.arcadeotaku.com/images/3/34 ... l_full.pdf

[BareKnuckleRoo]

Afraid not, only a couple of Futari boards.

According to the symptoms, and the manual (thank you!), what I need to check are the components around U601 - I cannot locate U601. I think it's supposed be the chip at the top right corner of this cap map:

http://wiki.arcadeotaku.com/w/File:MS-2931_cap-map.jpg

But on my board, the chip is obscured by a metal box with a pair of holes in it: http://i.imgur.com/K3I1i9k.jpg I can't tell if it's soldered on, but I can't budge it with my fingers. Is this supposed to be there? I don't know if there's any components within I can check, but I figured I'd ask.

[jepjepjep]

It looks like it might just be a monitor setting if the picture is rolling. I've run into that on one of my pcbs with my MS2931. Something to try at least if you haven't already.

The setting is in the Factory Menu:
Hold UP + DOWN then enter the monitor service menu
FHO15 is the setting that worked for me (just nudging it up or down a click or two).

[xga]

Afraid not, only a couple of Futari boards.

According to the symptoms, and the manual (thank you!), what I need to check are the components around U601 - I cannot locate U601. I think it's supposed be the chip at the top right corner of this cap map:

http://wiki.arcadeotaku.com/w/File:MS-2931_cap-map.jpg

But on my board, the chip is obscured by a metal box with a pair of holes in it: http://i.imgur.com/K3I1i9k.jpg I can't tell if it's soldered on, but I can't budge it with my fingers. Is this supposed to be there? I don't know if there's any components within I can check, but I figured I'd ask.

Does your chassis look like this?



If so, you have a Nanao MS2933 chassis, not a MS2931. In terms of features, they are pretty much identical (auto tri-sync etc), but the board layout is slightly different and some of the troubleshooting locations in the MS2931 service manual may not apply to the MS2933. I've never seen a service manual for a MS2933. Perhaps Uncletom has one?

[BareKnuckleRoo]

That's definitely what I have - no wonder the manual was confusing me. I'll have to see if I can find a manual or schematic for the MS-2933. Thanks for the info!

[xga]

Perhaps PM uncletom or Grantspain over at arcadeotaku.com to see if they have a copy or can help.

[kuze]

I would be interested in the service manual for that chassis if you end up finding it.

[BareKnuckleRoo]

Friend brought over a copy of Hokuto no Ken - tried it out, lo and behold, no sync issues. Some green lines on some of the text means I may need to mess with the monitor or pot settings, but otherwise works fine. Seems the Net City just doesn't like my Futari boards...?

Only problem now is the volume is ear blastingly loud, so I need to get the volume knob wired up. There appear to be a few cut wires coming from the circuit board with the knob. Any guidance on how this should be wired to the speaker wires would be appreciated.

Edit: well there's a sound volume option in the test menu so that works

[kuze]

Friend brought over a copy of Hokuto no Ken - tried it out, lo and behold, no sync issues. Some green lines on some of the text means I may need to mess with the monitor or pot settings, but otherwise works fine. Seems the Net City just doesn't like my Futari boards...?

Only problem now is the volume is ear blastingly loud, so I need to get the volume knob wired up. There appear to be a few cut wires coming from the circuit board with the knob. Any guidance on how this should be wired to the speaker wires would be appreciated.

Edit: well there's a sound volume option in the test menu so that works

I'll try Futari on my 2933 when I get a chance and will see if I can replicate the issue. I normally play it on a 2930.

[BareKnuckleRoo]

Okay, so had a chance to try a few different games:

Mushi Futari, Deathsmiles MBL - both these refuse to v-sync and exhibit 'rolling' screen issues

Mr. Driller G, Aqua Rush - major colour and screen problems. Aqua Rush occasionally displayed vsync screen wobble.

None of these boards exhibit problems when played on other cabs. On the games that do sync properly, some really wacky colour issues happen, such as colours being flat out displayed wrong, or in garish tones. There's also horizontal bars everywhere, and on Mr. Driller G, the entire line at the height of the air meter flashes in time with the air meter's animation, causing the bricks at that height to appear animated. Aqua Rush is playable, but it's a mess of horizontal lines, blurryness, weird colours, etc. See pictures here.

The only game I've tried on it that works fine is Hokuto no Ken (Atomiswave), it's quite blurry, but with contrast adjustments it looks almost 100%, no colour issues. Very odd.

Any suggestions? Should I just get a new chassis or monitor?

[BareKnuckleRoo]

Huge thanks to Rick over at Nieman Video Displays for helping to get this working! http://www.niemandisplays.com/

The board on the back of the TV ended up needing to be replaced for an older one with an analog adjustment, but it works fantastic now and looks gorgeous. He's still tinkering with the original board that was on it, but I've mostly written it off. It VSyncs perfectly with CAVE boards now (I just need to update some of the wiring in the monitor to make it a bit longer to be able to rotate it), and looks great with the games it didn't support before.

Just look at those gorgeous colours on Mister Driller G! http://imgur.com/a/2uIBB

Also replaced the speakers on it (one of them was busted), so the Net City runs like brand new!