Add on board for Analog CRT centering and protection?

Discussion about displays and related hardware including MiSTer filters and video settings.
User avatar
mmmonkey
Posts: 19
Joined: Sun May 24, 2020 7:05 pm
Been thanked: 6 times

Add on board for Analog CRT centering and protection?

Unread post by 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
Posts: 15
Joined: Sun May 24, 2020 7:11 pm
Has thanked: 4 times
Been thanked: 1 time

Re: Add on board for Analog CRT centering and protection?

Unread post by 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.
User avatar
Sorgelig
Site Admin
Posts: 877
Joined: Thu May 21, 2020 9:49 pm
Has thanked: 2 times
Been thanked: 211 times

Re: Add on board for Analog CRT centering and protection?

Unread post by 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
Posts: 15
Joined: Sun May 24, 2020 7:11 pm
Has thanked: 4 times
Been thanked: 1 time

Re: Add on board for Analog CRT centering and protection?

Unread post by onaryc »

yes you are right, everything/everyone will die. But this is life, trying to enjoy things while it lasts.
Naku
Posts: 1
Joined: Mon May 25, 2020 3:18 pm

Re: Add on board for Analog CRT centering and protection?

Unread post by Naku »

I expected more technical than spiritual with the new forum :)
akeley
Top Contributor
Posts: 1303
Joined: Mon May 25, 2020 7:54 pm
Has thanked: 416 times
Been thanked: 399 times

Re: Add on board for Analog CRT centering and protection?

Unread post by akeley »

mmmonkey wrote: Mon May 25, 2020 8:41 am 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.
User avatar
mmmonkey
Posts: 19
Joined: Sun May 24, 2020 7:05 pm
Been thanked: 6 times

Re: Add on board for Analog CRT centering and protection?

Unread post by 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
Posts: 2
Joined: Sun May 24, 2020 9:25 pm

CRT screen offset adjust

Unread post by 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?
User avatar
rastan
Posts: 6
Joined: Tue May 26, 2020 4:49 am
Has thanked: 4 times
Been thanked: 1 time

Re: Add on board for Analog CRT centering and protection?

Unread post by rastan »

imo an extron RGB interface is worth it, because each core (on my CRT at least) requires different centering adjustments.
akeley
Top Contributor
Posts: 1303
Joined: Mon May 25, 2020 7:54 pm
Has thanked: 416 times
Been thanked: 399 times

Re: Add on board for Analog CRT centering and protection?

Unread post by akeley »

mmmonkey wrote: Mon May 25, 2020 10:00 pm 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...
User avatar
mmmonkey
Posts: 19
Joined: Sun May 24, 2020 7:05 pm
Been thanked: 6 times

Re: Add on board for Analog CRT centering and protection?

Unread post by 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
Posts: 257
Joined: Sun May 24, 2020 9:06 pm
Has thanked: 64 times
Been thanked: 13 times

Re: Add on board for Analog CRT centering and protection?

Unread post by retrorepair »

Sorgelig wrote: Mon May 25, 2020 10:06 am 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
Top Contributor
Posts: 1303
Joined: Mon May 25, 2020 7:54 pm
Has thanked: 416 times
Been thanked: 399 times

Re: Add on board for Analog CRT centering and protection?

Unread post by akeley »

retrorepair wrote: Wed May 27, 2020 10:52 pm 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
Posts: 11
Joined: Wed May 27, 2020 11:16 pm

Re: Add on board for Analog CRT centering and protection?

Unread post by 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.
User avatar
Sigismond0
Posts: 339
Joined: Mon May 25, 2020 2:21 am
Has thanked: 1 time
Been thanked: 66 times

Re: Add on board for Analog CRT centering and protection?

Unread post by Sigismond0 »

retrorepair wrote: Wed May 27, 2020 10:52 pmThe 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
Top Contributor
Posts: 1303
Joined: Mon May 25, 2020 7:54 pm
Has thanked: 416 times
Been thanked: 399 times

Re: Add on board for Analog CRT centering and protection?

Unread post by akeley »

Sefirosu789 wrote: Thu May 28, 2020 2:01 pm 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
Posts: 257
Joined: Sun May 24, 2020 9:06 pm
Has thanked: 64 times
Been thanked: 13 times

Re: Add on board for Analog CRT centering and protection?

Unread post by retrorepair »

Sefirosu789 wrote: Thu May 28, 2020 2:01 pm 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.
User avatar
MickGyver
Posts: 13
Joined: Sun May 24, 2020 6:59 pm

Re: Add on board for Analog CRT centering and protection?

Unread post by MickGyver »

retrorepair wrote: Wed May 27, 2020 10:52 pm 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! :)
User avatar
Sorgelig
Site Admin
Posts: 877
Joined: Thu May 21, 2020 9:49 pm
Has thanked: 2 times
Been thanked: 211 times

Re: Add on board for Analog CRT centering and protection?

Unread post by 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.
User avatar
MottZilla
Posts: 43
Joined: Mon May 25, 2020 6:36 am
Has thanked: 1 time
Been thanked: 5 times

Re: Add on board for Analog CRT centering and protection?

Unread post by MottZilla »

Sorgelig wrote: Mon Jun 01, 2020 6:47 pm 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.
User avatar
Sigismond0
Posts: 339
Joined: Mon May 25, 2020 2:21 am
Has thanked: 1 time
Been thanked: 66 times

Re: Add on board for Analog CRT centering and protection?

Unread post by 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
uHB3671.jpg (562.92 KiB) Viewed 9706 times

NES core - Centered
foGIZbb.jpg
foGIZbb.jpg (478.81 KiB) Viewed 9706 times

Genesis core - Slightly to the left of center
hC1bC4D.jpg
hC1bC4D.jpg (3.03 MiB) Viewed 9706 times

TG16 core - Slightly to the right of center.
x6BUMZC.jpg
x6BUMZC.jpg (2.35 MiB) Viewed 9706 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
bOw1S83.jpg (587.53 KiB) Viewed 9706 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.
Post Reply