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

FYI, I tested My Model 2 boards with the LCD1970NX last night, and they're EXTREMELY washed out- I need to add resistors to the RGB output of the Model2 to get it down to the 0.7v range, although this is somewhat of a norm for JAMMA and similar.
The image was stable and fit on the screen great however!
 
Is there any 26''+LCD that could be a direct replacement for a normal 24Khz CRT?
 
I have a suspicion that there are some, but other than ones advertised as such, the options will be low.
Even lower if you want a proper 4:3 (or close) ratio screen.
There simply aren't many LARGE 4:3 LCD out there...
 
I guess 16:9 is also acceptable. Anyone can provide some specific models?
 
I think riverservice used to have a few options, but they were mad expensive...
As far as consumer level tv/monitors that would work- not a clue in that size range.
Take a 24k pcb with you to your local electronics/appliance store and start testing! :P
 
Darksoft said:
I guess 16:9 is also acceptable. Anyone can provide some specific models?
Click to expand...
To my knowledge no one has ever manufactured an LCD over 21in with a 4:3 aspect ratio. the 20in and 21in 4:3 LCDs are incredibly rare (only 2 or 3 monitors this size and aspect ratio exist) and none of them to my knowledge support 15K or 25K resolutions.

For my research I looked specifically for LCDs in the 19in-24in rage from brands known to have some support for 25K resolution modes. I looked up the spec sheet for about 100 different LCD models and listed everything I found on page 2 of this thread. I don't think I came across anything in the 26in+ range, the closest I found was the BenQ G2411HD and the ViewSonic VG2437Smc which are both 24" LCDs. Even if the spec sheet claims support still I'm skeptical if support exists since chances are 99% of users wont be using the display for that. 26in is kind of the magic number were you jump from being a big "monitor" to a small "hdtv" and I think once you make that jump the support for 25K likely falls off a cliff.

It's also worth noting that the NEC 1970 that both I and Defor are using DOES NOT officially support 15K or 25K resolutions, even though it works.

TLDR: I haven't come across any 26in+ 25K capable LCDs, nor have I found any indication that anyone else has even looked for one yet. you might have to to just look up spec sheets and take a gamble.

EDIT: A quick google search for "27in monitor KHz" turned up two models that CLAIM to support 24K modes:
Asus PB278Q
HP EliteDisplay E271i
worth investigating but obviously buy at your own risk. A similar search in the 32in range has turned up nothing.
 
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defor said:
Swapped the main logic pcb, and 15k looks nice, no more wierd interlace tearing- some flickering in the interlace as you mention but good enough for casual play/test bench usage.
Click to expand...
I've started a spread sheet to start cataloging this stuff here: https://docs.google.com/spreadsheets/d/1HfY6nwoDXw9qPSlJycNuzhJRumG9Adbb2GCb9MV6R3o/edit?usp=sharing

for this monitor I was wondering if there is anything on the back label to help differentiate the loder revisions vs the newer revisions without having to check the firmware or take it apart.

I'm also curious if you tested non-interlaced 15K or 25K sources on the "bad" control board... I'd be curious if the problem is just with interlaced content or just with 15K content, as this monitor may still be useful if it only has a problem with interlaced sources.
 
So I was doing some work on my DDR PC over the weakend and since it's setup with CRT_EmuDriver I decided to go through the list of 102 default resolutions and see what worked on the NEC 1970NX...

240x224@60p - out of range
240x240@60p - stable
248x224@60p - out of range
248x240@60p - stable
256x224@60p - out of range
256x240@60p - stable
264x224@60p - out of range
264x240@60p - stable
272x224@60p - out of range
280x224@60p - out of range
280x240@60p - stable
288x224@60p - out of range
288x240@60p - stable
296x224@60p - out of range
296x240@60p - stable
304x224@60p - out of range
304x480@60p - stable
320x200@60p - stable but letterboxed
320x200@75p - stable
320x224@60p - out of range
320x240@60p - stable
320x240@75p - stable
328x224@60p - out of range
336x240@60p - stable
344x240@60p - stable
352x224@60p - out of range
252x240@60p - stable
360x224@60p - out of range
360x240@60p - stable
368x224@60p - out of range
368x240@60p - stable
376x240@60p - stable
384x224@60p - out of range
384x240@60p - stable
400x224@60p - out of range
400x232@60p - stable (has trouble auto adjusting and states out of range even though picture displays)
400x240@60p - stable
400x248@60p - stable
400x300@60p - stable (large black bar on top)
400x300@75p - stable
416x224@60p - out of range
432x224@60p - out of range
432x240@60p - stable
432x248@60p - stable
448x224@60p - out of range
448x240@60p - stable
456x232@60p - stable (has trouble auto adjusting and states out of range even though picture displays)
456x240@60p - stable
464x224@60p - out of range
480x224@60p - out of range
480x240@60p - stable
480x464@60p - stable (small black bar on top)
480x480@60p - stable
496x224@60p - out of range
496x240@60p - stable
496x480@60p - stable
512x224@60p - out of range
512x240@60p - stable
512x384@60p - stable (uneven letterboxing)
512x384@75p - stable (small back bar on top)
512x400@60p - stable
512x432@60p - stable
512x448@60p - stable
512x480@60p - stable
544x480@60p - stable
560x240@60p - stable
576x224@60p - stable
576x400@60p - stable
576x432@60p - stable
600x240@60p - stable
640x224@60p - out of range
640x240@60p - stable
640x400@60p - stable (uneven letterboxing)
640x400@75p - stable
640x480@60p - stable
640x480@72p - stable
640x480@75p - stable
648x240@60p - stable
664x496@60p - stable
672x224@60p - out of range
672x240@60p - stable
704x240@60p - stable
704x480@60p - stable
720x480@60p - stable
800x600@56p - stable
800x600@60p - stable
800x600@70p - stable
800x600@72p - stable
800x600@75p - stable
1024x768@60p - stable
1024x768@70p - stable
1024x768@72p - stable
1024x768@75p - stable
1152x864@60p - stable
1152x864@70p - stable
1152x864@75p - stable
1280x240@60p - stable (but looks terrible)
1280x720@60p - stable
1280x1024@60p - stable
1280x1024@70p - stable
1280x1024@75p - stable


In short 224p is unsupported 232p works but the monitor thinks that it doesn't and everything else I threw at it worked pretty well.
I did notice that most of these resolutions reported as being something else. most of the time the info box would report the resolution at it's nearest double so for instance (15K) 240P was reporting as (31K) 480P. Since this monitor doesn't officially support 15K resolutions I'm curious if this is just a quirk in the hardware design.
 
I just bought a second (white this time) 1970nx and matching soundbar for my P2 testbed setup, should be here tomorrow...

So, let's talk 15k...
When I feed the monitor video from traditional (non 31k/vga sources), while it looks fine, the color is massively washed out- it's my assumption this is due to the voltage levels being way too high, and no compensation inside the 1970NX... I've heard that 220ohm resistors are needed- is this the optimal value to use? Also will the sync signal need to be limited as well?

I'm thinking to make a simple little box with the sync separator, switchable voltage levels, powered from the speaker power jack that's on the bottom, just to mahe everything simple and self-contained- then I can just run vga cable or BNC3/4/5 to vga
 
defor said:
So, let's talk 15k...
When I feed the monitor video from traditional (non 31k/vga sources), while it looks fine, the color is massively washed out- it's my assumption this is due to the voltage levels being way too high, and no compensation inside the 1970NX... I've heard that 220ohm resistors are needed- is this the optimal value to use? Also will the sync signal need to be limited as well?
Click to expand...
sync signal: no. the sync signal whether RGB or VGA should be a 5V square wave so there's no need to adjust it.

When running an RGB signal from a JAMMA board to my PVM over SCART to BNC I put 330ohm resistors on the outputs... this is because the JAMMA standard calls for 0 to 4V range on the color signal output. arcade monitors are tuned for and expect this. the VGA as well as the SCART (and as it seems BNC standard used by PVMs) expects a range of 0 to 0.7V. so the 330ohm resistors are there purely to drop the range down from 4V at the peak to 0.7V at the peak.

I went though the math and my research on this here: JAMMA to VGA and JAMMA to SCART

With that said. hooking up a JVS compliant source such as a NAOMI shouldn't require any resistors or other tweaks to the signal I will say that my System 256 even in 31K/0.7V output mode blooms, and I don't trust that it's actually attenuating the voltages down below 0.7V like it should.

So for the color channels 330ohm resistors seem to be the most appropriate according to math, and my testing. There was a marked improvement going from no resistors to 150ohm, and again from 150 to 220 and I'd suspect that with some games a lower value might be more appropriate.

you MAY need a sync separator to split the C-Sync to H and V sync. I haven't actually tested a JAMMA board on this monitor yet as I haven't got around to building my VGA cable so I don't know if it can handle C sync on the H pin with no V sync supplied. This isn't a problem with JVS PCBs even in 15K mode because they have separate H and V sync outputs.
 
Derick2k said:
I picked up an NEC Accusync LCD71V to use on my test bench, hopefully it does the job.
Click to expand...
Do you know something I don't? I don't recall that model coming up and spec sheets list that as 31K and up only.
 
twistedsymphony said:
Derick2k said:
I picked up an NEC Accusync LCD71V to use on my test bench, hopefully it does the job.
Click to expand...
Do you know something I don't? I don't recall that model coming up and spec sheets list that as 31K and up only.
Click to expand...
Its not listed on the specs, but apparently it does work with 15 & 24khz, read about it on a couple of amiga forums since I was looking for a monitor for my A1200. Took a gamble on it, will confirm once I have a chance to test it.
 
twistedsymphony said:
sync signal: no. the sync signal whether RGB or VGA should be a 5V square wave so there's no need to adjust it.
When running an RGB signal from a JAMMA board to my PVM over SCART to BNC I put 330ohm resistors on the outputs... this is because the JAMMA standard calls for 0 to 4V range on the color signal output. arcade monitors are tuned for and expect this. the VGA as well as the SCART (and as it seems BNC standard used by PVMs) expects a range of 0 to 0.7V. so the 330ohm resistors are there purely to drop the range down from 4V at the peak to 0.7V at the peak.

I went though the math and my research on this here: JAMMA to VGA and JAMMA to SCART

With that said. hooking up a JVS compliant source such as a NAOMI shouldn't require any resistors or other tweaks to the signal I will say that my System 256 even in 31K/0.7V output mode blooms, and I don't trust that it's actually attenuating the voltages down below 0.7V like it should.

So for the color channels 330ohm resistors seem to be the most appropriate according to math, and my testing. There was a marked improvement going from no resistors to 150ohm, and again from 150 to 220 and I'd suspect that with some games a lower value might be more appropriate.

you MAY need a sync separator to split the C-Sync to H and V sync. I haven't actually tested a JAMMA board on this monitor yet as I haven't got around to building my VGA cable so I don't know if it can handle C sync on the H pin with no V sync supplied. This isn't a problem with JVS PCBs even in 15K mode because they have separate H and V sync outputs.
Click to expand...
Thanks for the feedback-Sounds like mostly I was right in my logic :)
I get the overbought when I use 15k on the 2x6 with the voltage dip set- clearly this isn't a big deal, but other things I commonly work on (Model 2 for example) don't have that option...
As far as sync separation goes, I'm planning to implement some switching to switch between SOG, CSYNC, and Separate- the 1970NX definitely does not support CSYNC- I've yet to test SOG, but I'm expecting no support there either, but adding an LM1881 or similar to the setup isn't a huge problem.
 
I don't know what kind of voltage levels come out of the RGB port on Model 2 and Model 3 games. those are kind of in a weird spot between JAMMA and JVS. you could probably test it by measuring the voltage while showing a full solid color on the screen in test mode. (ie: display a full red screen and test voltage on the red pin, etc.)
 
Another LCD1970NX firmware version to add to the pile:

Verified GOOD:
F/W ID C59SLP10
F/W VER. 1.1.10

Verified BAD:
F/W ID C39SAP10
F/W VER. 1.1.12

F/W ID CB9SSP10
F/W VER. 1.2.05
 
defor said:
Another LCD1970NX firmware version to add to the pile:

Verified GOOD:
F/W ID C59SLP10
F/W VER. 1.1.10

Verified BAD:
F/W ID C39SAP10
F/W VER. 1.1.12

F/W ID CB9SSP10
F/W VER. 1.2.05
Click to expand...
Maybe the good firmware can be flashed to over the ones that dont work?!
 
This makes me wonder if other LCDs could be "hacked" for better resolution support, or even to bypass some image processing for lower lag.
 
if by "better resolution support" you mean "more resolution options", then yes- most of the time they use off the shelf analog to digital converters with a custom rom, and with some work, this CAN be modified to do what you speak of...
The downside is that every monitor's gonna be different and need a custom rom hacked/developed for it.

If you look on ebay,there's a few vendors out of China that will, given a part number for an lcd panel, give you a fully working hdmi, dvi, vga, or whatever interface, wired up and ready to just plug into the bare panel.. some of them MAY have converters that will do low and medium res video as long as the firmware is setup to do it.. but the video chips on the boards will need the capability as well.

the good news? we know that gm5221-lf based monitors should at least in theory support everything here.
 
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