Analog Interactive Neogeo CMVS Not Syncing to BVM-A20F1U

[BVM-PVM]

Hey guys, I have a Analog Interactive Neogeo CMVS Slim that I have been trying to hook up to my Sony BVM-A20F1U with no luck. I have tried Composite video, Component video, and RGB scart. All I get is a out of sync picture that moves up and down really fast. Also I use this Scart to BNC adapter http://www.retrogamingcables.com/female ... ipper.html

Any Ideas how to fix this?

[Fudoh]

In theory it's possible that the A20 doensn't like the 59.15Hz the MVS does output, since it's rather far from the standard NTSC timings. But I guess there's no way of knowing for sure unless you find another BVM-A user to check it for you.

Other RGB sources work fine though, don't they ?

[BVM-PVM]

In theory it's possible that the A20 doensn't like the 59.15Hz the MVS does output, since it's rather far from the standard NTSC timings. But I guess there's no way of knowing for sure unless you find another BVM-A user to check it for you.

Other RGB sources work fine though, don't they ?

Yes, all my other consoles work fine with RGB on monitor. Does anyone have a cmvs working on a BVM-A20F1U or other BVM monitor?

[fagin]

I'm sure I've tested on my BVM (2010P) fine. If I get time over the next couple of days, I'll re-test.

[alamone]

In theory it's possible that the A20 doensn't like the 59.15Hz the MVS does output, since it's rather far from the standard NTSC timings.

It's not "theory", it's reality. The multiformat PVMs and probably BVMs have a much narrower sync range for 15KHz sources.
At one point I had a PVM14-L5 multiformat PVM, and none of the PCBs I tested would sync correctly, even easy cases like 1943.
On the other hand, standard consumer and console stuff would sync fine.

My suggestion is to dump that multiformat PVM and get a 15KHz only model.
If you want 31 KHz, you have your pick of any bog standard VGA monitor or LCD.

Edit: I forgot but 24 KHz doesn't even work on multiformat PVMs, so really there's little reason
to get one as it does not replace a tri-sync. Get the right tool for the job.

[BVM-PVM]

In theory it's possible that the A20 doensn't like the 59.15Hz the MVS does output, since it's rather far from the standard NTSC timings.

It's not "theory", it's reality. The multiformat PVMs and probably BVMs have a much narrower sync range for 15KHz sources.
At one point I had a PVM14-L5 multiformat PVM, and none of the PCBs I tested would sync correctly, even easy cases like 1943.
On the other hand, standard consumer and console stuff would sync fine.

My suggestion is to dump that multiformat PVM and get a 15KHz only model.
If you want 31 KHz, you have your pick of any bog standard VGA monitor or LCD.

Edit: I forgot but 24 KHz doesn't even work on multiformat PVMs, so really there's little reason
to get one as it does not replace a tri-sync. Get the right tool for the job.

I just tried my Modded Neogeo AES on the BVM to see if it was the same as the CMVS. Component Video had a distorted image on just the top half of the screen. Composite video was completely fine with no sync issues.

I opened up my CMVS scart cable to see what was inside. There is one resister wired inside and that's it. Should my scart cable be wired with more resistors? Or does it need capacitors?

[Fudoh]

The AES is closer to NTSC specs than the MVS is. I think something like 59.8 Hz compared to the 59.1 on the MVS.

I think Chris uses a RGB encoder IC, so the cable might be right without additional resistors on the RGB lines. It's probably worth a try to add a LM1881 to stabilize the sync signal before giving up on the whole BVM-A/MVS combo.

[BVM-PVM]

I already have a sync stripper in my scart to bnc adapter. Do you think having another sync cleaner inside the cmvs scart cable would help?

[Fudoh]

No, but maybe you should give it a try without the stripper then. You can easily disable the stripper in your breakout adapter and re-enable it later on.

[BVM-PVM]

No, but maybe you should give it a try without the stripper then. You can easily disable the stripper in your breakout adapter and re-enable it later on.

How do I disable it, Desolder the tiny board off?

[Fudoh]

you just need to bypass the sync in / sync out pins, so the MVS's sync gets directly connected to the monitor.

[BVM-PVM]

you just need to bypass the sync in / sync out pins, so the MVS's sync gets directly connected to the monitor.

Just tried it without the sync stripper. I still got the out of sync shaky screen. Do you have anymore ideas?

[BVM-PVM]

Bump

[mesmer]

I have a BVM-A20, and can confirm that it is very picky. I've spent many hours perfecting my 15khz modelines for soft15k. Almost none of the default ones worked. My consoles (snes, saturn, etc) all work fine over RGB. I have an MVS and was planning to build a supergun. This is an interesting development.

[Ed Oscuro]

It's not "theory", it's reality. The multiformat PVMs and probably BVMs have a much narrower sync range for 15KHz sources.

Some reality! My PVM 20L5 has played everything I've thrown at it so far, including Raiden II. The only complaint I have is that there is a bit of distortion at the top of the image (in normal TV orientation - more problematic in some games than others, like Aliens and not Raiden II, surprisingly) but I have so far not ruled out a fault in the supergun or cables, and this appears (to some degree) in all games across that connection and doesn't get more severe the farther from 59.97Hz the board gets. This is without using any fancy sync processing - just RGB+sync.