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View topic - Zig Zag lines (similar to jailbars) on SMS Power Base

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  • Joined: 11 Jul 2022
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Zig Zag lines (similar to jailbars) on SMS Power Base
Post Posted: Mon Jul 11, 2022 9:39 pm
Hello, I'm new here

I recently got a Master System 1 Power Base, pal version. I connected it with a RGB Scart (brand: consolegoods)

I noticed that there is a ziz zag lines pattern on screen, especially visible on light blue backgrounds.
It's similar to the jailbars but it's probably a different issue, I added an image for reference

Do you know how can I solve this issue? Could it be the RGB scart?

Thank you in advance
zigzag.jpg (528.17 KB)
zigzag.jpg

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  • Joined: 11 Jul 2022
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Post Posted: Tue Jul 19, 2022 3:52 pm
I tried on a CRT tv and it resemble more a dot pattern, instead of the zig zag pattern that appear on hdtv, don't know if this can help.
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  • Joined: 24 Mar 2021
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Post Posted: Tue Jul 19, 2022 5:20 pm
I think that's the PAL chroma frequency leaking in from the RGB-to-CVBS converter on the board.

You may need to disconnect the clock source from the CXA1145 to get rid of them? I think I remember reading someone mentioning that on previous guides to optimizing video quality out of the SMS and SMD, too
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Post Posted: Thu Jul 21, 2022 1:39 pm
lidnariq wrote
I think that's the PAL chroma frequency leaking in from the RGB-to-CVBS converter on the board.

You may need to disconnect the clock source from the CXA1145 to get rid of them? I think I remember reading someone mentioning that on previous guides to optimizing video quality out of the SMS and SMD, too



I see, not good since I would try t avoid modding the console.

any chance it could be also the RGB scart not properly shielded or something else?
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  • Joined: 24 Mar 2021
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Post Posted: Thu Jul 21, 2022 4:48 pm
I suppose I don't see any in the white clouds where there is no color, so your hypothesis is also credible - it could be due to the CVBS wire not being shielded from the RGB component wires inside the cable.
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Post Posted: Sun Jul 24, 2022 8:20 pm
lidnariq wrote
I suppose I don't see any in the white clouds where there is no color, so your hypothesis is also credible - it could be due to the CVBS wire not being shielded from the RGB component wires inside the cable.


Yes, it seems the zig zag pattern appear especially on ligh blue backgrounds, but other colors doesn't seems to be affected.

In case it's the scart anyone know a good brand (possibly at a decent price too) for a good shielded RGB scart?

If I remmber correctly, the Mega Drive 1 scarts should work too, right?
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Post Posted: Thu Jul 28, 2022 8:48 pm
update:

maybe it can help to address the issue

I tried to connect the SMS to a scart switcher that has a dedicated RGB button, always using the same RGB scart.

-When the RGB button is ON, the zig zag lines are there, on selected colors (testing with Hang On, light blu especially is affected by zig zag lines, the grey shows instead a jailbars pattern, while the white and dark blue are perfect without issues).

-When the RGB button is OFF, no zig zag line or jailbars at all, of course the video quality degrades a lot.

same scart.

Do you think it's an issue with the CXA1145 chip and definitely require the mod, or it can be the RGB scart and it's worth to try a more espensive one?
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Post Posted: Tue Aug 02, 2022 5:34 am
This looks more like a cheapo SCART cable than anything else.
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  • Joined: 12 Dec 2010
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Post Posted: Tue Aug 02, 2022 8:19 am
These are supposed to be fantastic and are fully shielded and wired for C sync. (As such they don't do composite over SCART, a consideration if you need one that does.)

https://www.retrogamingcables.co.uk/sega/master-system-model-1/SEGA-MASTER-SYSTEM-1-RGB-SCART-CABLE-PACKAPUNCH-PRO

Got a Mega Drive with stereo sound one on its way. Not cheap but I used code 'SLR20' at checkout for 20% off.
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Post Posted: Wed Aug 03, 2022 2:09 pm
thank you guys!
It would be a good news for me if the culprit is my scart.

I'm not an expert, but scart with c-sync (like the packapunch ones) can be used on european TVs?
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Post Posted: Wed Aug 03, 2022 2:14 pm
Mine arrived yesterday, it's fantastic. I'm UK and using it on a PAL Sony Trinitron CRT. I'd try it on the LCD but it doesn't have a SCART socket.
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Post Posted: Fri Aug 05, 2022 12:57 pm
segasonic wrote
Mine arrived yesterday, it's fantastic. I'm UK and using it on a PAL Sony Trinitron CRT. I'd try it on the LCD but it doesn't have a SCART socket.


nice, no issues with jailbars or zigzag lines?
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Post Posted: Fri Aug 05, 2022 6:15 pm
Hunter wrote
segasonic wrote
Mine arrived yesterday, it's fantastic. I'm UK and using it on a PAL Sony Trinitron CRT. I'd try it on the LCD but it doesn't have a SCART socket.


nice, no issues with jailbars or zigzag lines?


No, it's crystal clear. Bit busy redecorating at the moment but I've got a smaller LCD that I think has a SCART socket, I'll try hooking it up to that when I get a chance. My cable should work on an SMS model 1 so I'll see how that looks.
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Post Posted: Sat Aug 06, 2022 10:00 am
PAL SMS1, 60Hz on a Samsung T24C350. Noticed some jailbars on the title screen backdrop but the blues in game look ok.

(The moire effect on the close ups wasn't evident on the screen itself, it just showed on the camera.)
20220806_105403.jpg (880.87 KB)
20220806_105403.jpg
20220806_105416.jpg (838.6 KB)
20220806_105416.jpg
20220806_105421.jpg (888.56 KB)
20220806_105421.jpg

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Post Posted: Sun Aug 07, 2022 7:38 pm
segasonic wrote
PAL SMS1, 60Hz on a Samsung T24C350. Noticed some jailbars on the title screen backdrop but the blues in game look ok.

(The moire effect on the close ups wasn't evident on the screen itself, it just showed on the camera.)


Thank you! Seems good in those photos.
Moire from what I know is normal when taking a photo of a monitor.

jailbars on Alex Kidd title screen backdrop, so the yellow is affected in that case?
Could you take a screen of this just for reference?
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Post Posted: Mon Aug 08, 2022 3:43 pm
Here you go. They're hard to see on photos, there's one every inch or so on the title screen. They're also faintly visible on the light blue screen border in game, the photo doesn't show them at all there.

I tried it on the CRT and there are no artefacts whatsoever, so I suspect they're something to do with the upscaler in the 1080p LCD rather than signal interference.

(Having trouble adding the photos from my phone, will edit on PC later)

Photos added.
TitleScreen.jpg (2.51 MB)
TitleScreen.jpg
InGame.jpg (1.37 MB)
InGame.jpg

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Post Posted: Tue Aug 09, 2022 2:21 pm
segasonic wrote
Here you go. They're hard to see on photos, there's one every inch or so on the title screen. They're also faintly visible on the light blue screen border in game, the photo doesn't show them at all there.

I tried it on the CRT and there are no artefacts whatsoever, so I suspect they're something to do with the upscaler in the 1080p LCD rather than signal interference.

(Having trouble adding the photos from my phone, will edit on PC later)

Photos added.


Thank you very much! :)

Yeah in the first photo they are faintly visible but I still noticed the pattern of one vertical line every inch or so.
In the second photo they are not noticeable.

It could still be a huge improvement compared to my situation where the vertical zig zag lines are clearly visible even in a photo.

Now that you mention, I wonder how much my zig zag line are the result of internal scaler (my tv is a plasma) and how much is the cable interference.
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