Add on board for Analog CRT centering and protection?

[mmmonkey]

I recently picked up a regular consumer CRT with RGB Scart input (living in a PAL land does have some advantages). I plan on using this with MiSTer and consoles such as Saturn, Dreamcast, N64 etc. Except RGB signals aren't centered on the screen.

I've been looking for days to get into the service menu to see about centering the image, but with no luck. Then I remembered a post on the old forum about which stemmed from the Direct Video Mod talk - where Sorgelig talked about, well this..

I think it's better to make some additional protection board for unprotected monitor which will measure the HSync and VSync periods and connect them to monitor only if they are within the range. I think simple Arduino board can handle this task. Additionally you can implement HSync/VSync position adjustment.

(just found it again via Google cache https://bit.ly/2ZzrQJK )

I don't have the knowledge to be able to design anything like this, only to maybe solder it up if a board and BOM was released. Is there still a demand for this?

I know there's some Extron units that can handle both H + V centering (list of them here - https://bit.ly/2Zzt4ok ), but I feel that's overkill for this and supply will dry up.

Thoughts anyone?

Pete

[onaryc]

Personally, i'm interested in having a protection board where one can set the range of the sync signal. I have an arcade cabinet display which can only take 31khz signal. It will be damaged with other frequencies.

I was planning in doing some tests, if i have some time, with arduino boards i ordered. But i never received them
I'm more a software guy and i, probably naively, think that you just have to link the sync signal to the board, test if the frequency is right and if not shut all connections. Perhaps there is a need of electrical protection, level shifter, ...

As for centering, Sorg's post suggest that tweaking the vsync/hsync could do the trick. Potentiometers can be used to play with it.

[Sorgelig]

Generally speaking i don't see a need to add such features for devices not in production already.
Just wait several years more - they will die all

[onaryc]

yes you are right, everything/everyone will die. But this is life, trying to enjoy things while it lasts.

[Naku]

I expected more technical than spiritual with the new forum

[akeley]

I recently picked up a regular consumer CRT with RGB Scart input (living in a PAL land does have some advantages). I plan on using this with MiSTer and consoles such as Saturn, Dreamcast, N64 etc. Except RGB signals aren't centered on the screen.

How badly are they misaligned? If it's just some slight differences (few centimeters her or there) then it's quite normal.

I have a heap of old micros and consoles, plus a few CRTs. There is no uniform "centering", probably due to different overscans and whatnot.
Some Sony Trinitrons also shift RGB to the right/left (the newer ones even have a special slider for that in the menu).

What model is your TV? Can't find the service code menu for it?

I don't think special board for that problem is necessary, but some H / V position tweaking options would be really welcome and appreciated.

[mmmonkey]

I guess non RGB mode it’s shifted about 5mm to the left, same source but with RGB enabled then it’s more like 10mm shifted. It’s pretty much the same for the different sources I’ve tried so far.

My TV is Panasonic TX-21S1T, it’s a Z5 chassis. One page I found said to put the TV to channel 60, set sharpness to minimum and then press the Timer Off button on the remote at the same time as the Vol Down on the TV. I don’t have ch60, it stops at 50, when I follow the rest of those notes though it runs a test but doesn’t give any opportunity to change any settings.

[Dirtbag]

There is no prefect one size fits all cores configuration for the H and V alignment on my CRT.

When messing with the CPS core i noticed it allowed for the H and V alignment to be offset. This would make for a very handy global feature. Is anything like this planned for the future?

[rastan]

imo an extron RGB interface is worth it, because each core (on my CRT at least) requires different centering adjustments.

[akeley]

My TV is Panasonic TX-21S1T, it’s a Z5 chassis. One page I found said to put the TV to channel 60, set sharpness to minimum and then press the Timer Off button on the remote at the same time as the Vol Down on the TV. I don’t have ch60, it stops at 50, when I follow the rest of those notes though it runs a test but doesn’t give any opportunity to change any settings.

Yes it can be difficult to find right, non-paywalled, manuals these days. Did you try this generic method? https://factory-reset.com/wiki/Panasonic_Service_Menu

I guess earlier I was thinking about off-centered borders I see in my micros. I can live with that, because the screen is still filled. But a black gap could be indeed annoying...5mm maybe no so much, but 1cm yes.

Getting MiSTer somewhere this week, guess I'll see how bad it is for myself then...

[mmmonkey]

Thanks for the link, I’ll try it out tomorrow.

Enjoy your MiSTer when you get it, I’ve found it a great distraction, and that was before the world went haywire!

EDIT - went through those options on that site, and still can't get into a recognisable service menu, then found this https://service-mode.com/panasonic.html but no luck either. I think I'll use an Extron as a short-term solution, and then research and see if I can understand how to implement a horizontal shift using a DIY solution.

[retrorepair]

Generally speaking i don't see a need to add such features for devices not in production already.
Just wait several years more - they will die all

I have a Sony Trinitron produced in 1983 which will probably outlive me.

Pretty much all CRTs will have an off centre RGB image as they are designed for broadcast signals which carry extra information in the blanking signal not present in RGB.

The h shift in the cps core works very well, I'd be happy to port it to other cores.

[akeley]

The h shift in the cps core works very well, I'd be happy to port it to other cores.

Please, good sir, it'd really make a lot of folks happy. It's one of these little things which make a big difference.

[Sefirosu789]

Nice idea but I think just getting an Extron RGB interface would do the trick. They are not expensive and they show up time to time on eBay.

[Sigismond0]

The h shift in the cps core works very well, I'd be happy to port it to other cores.

I think that would be an excellent solution. I think it has a vertical adjust, too, which would also be nice. This would let everyone put every core where they want it.

[akeley]

Nice idea but I think just getting an Extron RGB interface would do the trick. They are not expensive and they show up time to time on eBay.

Maybe not as expensive as other Extrons but still an extra expense. I'm also not a big fan of building big chains between source and display. Software implementation would be much handier (if it's not too dificult of course).

[retrorepair]

Nice idea but I think just getting an Extron RGB interface would do the trick. They are not expensive and they show up time to time on eBay.

I don't see the point when it can be right in the core menu without the need for extra components.

[MickGyver]

The h shift in the cps core works very well, I'd be happy to port it to other cores.

Please do, that would be fantastic!

[Sorgelig]

All cores must output original system video signal through VGA output.
Adding these shifts will require additional processing for Hsync/Vsync position. It means there must be additional video processing module which will analyse current signal and re-generate vsync/hsync. And not only hsync/vsync need to be processed but also hblank/vblank to make enough space after sync signals.
Overall it will be a complex module with some limitations. Some cores may generate interlaced video.

P.S.: modification of original video modules of cores is not acceptable.

[MottZilla]

All cores must output original system video signal through VGA output.
Adding these shifts will require additional processing for Hsync/Vsync position. It means there must be additional video processing module which will analyse current signal and re-generate vsync/hsync. And not only hsync/vsync need to be processed but also hblank/vblank to make enough space after sync signals.
Overall it will be a complex module with some limitations. Some cores may generate interlaced video.

P.S.: modification of original video modules of cores is not acceptable.

Other than when the CPS1 core was in development, I haven't noticed any other cores having a problem with shifted video. I agree that we should want the video output to match the original.

What cores are people having issues with image positioning and how bad are they? If they happen on the original systems then maybe their monitor needs adjustment.

[Sigismond0]

Not the sexiest pictures, but should be sufficient for demonstration of the issue. I cannot comment on how original consoles behave on this monitor. Maybe it's normal for the NeoGeo to be far to the right, and the Genesis to be slightly to the left. PVM calibration was done on SNES 240p suite, so centering/alignment are based on that. (Note that my tube does have a tiny bit of rotation, so the SNES core image looks off center. That's just an artifact of the photograph. The NES core image shows slivers of both edges of the grid overscan the top left and bottom right. SNES looks the same IRL, but it didn't capture well in the image.)

SNES core - Centered

uHB3671.jpg (562.92 KiB) Viewed 11291 times

NES core - Centered

foGIZbb.jpg (478.81 KiB) Viewed 11291 times

Genesis core - Slightly to the left of center

hC1bC4D.jpg (3.03 MiB) Viewed 11291 times

TG16 core - Slightly to the right of center.

x6BUMZC.jpg (2.35 MiB) Viewed 11291 times

NeoGeo core - Significantly to right of center (PVM in underscan mode to make it more obvious, but same amount of misalignment present in standard mode). No 240p presented here, but showing it as the core that seems to be the most deviant.

bOw1S83.jpg (587.53 KiB) Viewed 11291 times

Even if we come to the conclusion that this is expected normal behavior for the original hardware, I think H/V adjust should still be discussed as an option. HQ2X, adaptive composite blending, etc. aren't present on original hardware but they're included as QOL features. In my opinion, this type of functionality is more important than visual enhancements.

Edit: Looks like the TG16 just had its centering adjusted. Looks pretty good for me, it's maybe 1 or 2 dots off from SNES.