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NON-CRT Displays that support 15KHz and 25KHz resolutions

I see people make this mistake all the time, but the 1ms on the Asus monitor you're referring to is not the input lag of the monitor, it's the estimated time it takes for a pixel to change color (grey to grey). It's a largely meaningless marketing stat (a similar marketing stat would be LCD monitors/TVs that claim 1,000,000+:1 contrast ratio). A realistic number from that era of gaming monitor would be more like 10-14ms of lag instead of 1ms.

Real lag numbers are almost never stated (some companies have recently begun to explicitly state low input lag modes or features, but still dont give numbers), and usually obtained with testing with varying degrees of accuracy, usually with something like a Leo Bodnar tester, Time Sleuth, or a modded OSSC. Some sites like displaylag.com, rtings.com, and tftcentral.co.uk test for lag when they review a display. The website inputlag.science has some decent info on this subject.
 
I apologize if this isn't wholly about the monitors themselves, but I ended up soldering some male Dupont cables to my Sega Model 2 monitor cable (5-pin JST NH) and I was actually able to plug the Dupont cables into the pins of a male VGA plug, then following the pinouts I got a signal directly from the board, on my VG245!

Waverunner and Indy 500 play so much better natively there than via a Gonbes, but I ran into a problem where sometimes if I plug the ground wire into a different ground pin, I get either an overly bright picture where all things blue are white, etc, or the colors are slightly dark and overly saturated when connected to another GND (much more bearable than being overly bright, however). Do I need to run multiple ground wires together to get a more balanced picture?
 
nem said:
Model 3 outputs high impedance video from the VGA connector, that's why it's overly bright. You need something to bring down the levels.
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Model 2s seem to do that yeah. However, my video boards that I've had have balanced picture. In RGB mode of my Asus they look absolutely stunning.
 
Crap, I read your post completely wrong. Not sure what I was thinking.

But yes, Model 2 outputs high impedance video as well from CN7. You need to attenuate the signals.
 
nem said:
Crap, I read your post completely wrong. Not sure what I was thinking.

But yes, Model 2 outputs high impedance video as well from CN7. You need to attenuate the signals.
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Yes, OSSC gets that job done as my original Harley PCB (sent for repairs to Mr. Ken) ironically had this problem but from the VGA plug itself; you need to dial ADC gain down to 0 or 1. Unfortunately my OSSC is dead from having voltage or a bent pin from the SCART cable of my Saturn fed into the SCART port. Not a deal breaker splashing in on another one, but they're quite expensive sadly.
 
I happened to get ahold of a 5:4 panel -- Asus VB195T, which is about 11 years old, and testing my medium-res games, they all give a picture. Unfortunately, because this is a 5:4 monitor and not 4:3, the image of games is quite skinny and you lose a good deal of information from top and bottom, even after adjusting H and V positioning. There is some ghosting as well, but it works and is a lot more responsive than GBS8200/8220. I'll keep this as most 5:4/4:3 screens only do 480p and up, especially the Acers.
For Sega Model 2 I recommend grabbing one of these for screens that support 25khz. Dirt cheap and kinda act as a transducer for the board's relatively low power. I used some random connectors from a Scud Race harness to power this little guy.
s-l1600.jpg


I can confirm the Acer P191W and V193 displays do not work thru direct connect as I tried them once.
 

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But isn't it easier and better from the image to use the whole thing immediately via a frameister or mister in 15khz then with scanlines or am I misunderstanding it.🙃
 
To determine if my monitor is compatible with 15khz - Would running a NAOMI in 15khz mode and seeing a stable image suffice or would I need to do more tests like using a JAMMA PCB + HAS/HD15 combo?

I think I have an ASUS monitor I could add to the list but I don't want to give the wrong information.
 
xodaraP said:
NAOMI in 15k will tell you if the monitor can sync 15k

But if you’re running an LCD you should be running 31k for NAOMI even if the monitor supports 15k
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Yeah like one day I had my NAOMI running in 15k by accident [went from PVM -> ASUS LCD]. When I booted it up everything was synced and running without any issues and was surprised. Shortly after I put it back to 31k though. 😅

The monitor in question is: ASUS VP249QGR from 2019 ~ 2020.

Thanks for the confirmation.

Edit: There’s also a similar model “Asus TUF GAMING VG249Q” that could potentially support 15k as well. It’s a successor model to the QGR and has VGA built in.
 
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Naomi's 15khz mode is 480i, which isn't that unusual for modern LCDs to support. What's more rare is a modern LCD that displays native 240p signals correctly without converting them into 480i, which has a very negative effect on image quality. I haven't really reviewed this whole thread, but my assumption is that when we are talking about 15khz support, we are specifically talking about progressive signals instead of interlaced.
 
Zepherino said:
Naomi's 15khz mode is 480i, which isn't that unusual for modern LCDs to support. What's more rare is a modern LCD that displays native 240p signals correctly without converting them into 480i, which has a very negative effect on image quality. I haven't really reviewed this whole thread, but my assumption is that when we are talking about 15khz support, we are specifically talking about progressive signals instead of interlaced.
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Ah I understand now in regards to image quality that actually makes sense now. When a monitor does that kind of 480i conversion, does that also mess with input lag as well when going Naomi 15k -> ASUS or HAS/HD15 -> ASUS? [I don’t know the technicalities or effects there so I’m asking.]

I pretty much read the original post within this thread, remembered what my ASUS monitor did on 15k mode and figured it was okay to bring up in case anyone comes across that model. 😅
 
Likely so, but the only way to know for sure is to test it.

In my experience testing various displays with Leo Bodnar and Time Sleuth, interlace signals tends to have a bit more lag than progressive signals (usually about 1 frame or more), but there are various exceptions to this, which is why testing is the only way to be sure.

This is why OSSC/Framemeister/Retrotink exists. No need to search around for old, difficult to obtain LCDs (that also don't perform well in terms of pixel response time) when you can use a good scaler to give a modern display a signal it performs well with. In general, modern gaming LCDs will blow older LCDs out of the water in terms of pixel response time and total display lag. Most of the time, hunting for older displays is only worth it for very niche reasons like fitment (i.e. you hate pillar boxing and specifically want a 4:3 panel).
 
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