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PostPosted: Sat Jan 27, 2018 6:17 pm 
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Hi. I have a 1 chip PAL SNES and I lifted pin 111. I have a switch currently which connects 5v to pin 111 or gnd to 111. When I set it to 50hz it works but when I set it to 60hz it just jumps in black and white. Is it true I just need to use an RGB cable? Also I seen a video someone playing the PAL super Mario world game but they we're allowed to switch it to 60hz. Do I just need to lift leg 4 and do the region lockout mod to run it? Also does doing the region mod fix the screen problems in 60hz or is it because I have a different crystal and just need an RGB cable. Thanks.


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PostPosted: Sat Jan 27, 2018 6:36 pm 
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Do you know whether your TV can decode PAL60 video?

Someone asked this question of an older 3-chip PAL SNES, but for them they started with an NTSC SNES and had problems switching to 50Hz modes (as a result, said SNES was always emitting NTSC color modulation regardless of vsync rate)


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PostPosted: Sat Jan 27, 2018 6:53 pm 
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lidnariq wrote:
Do you know whether your TV can decode PAL60 video?

Someone asked this question of an older 3-chip PAL SNES, but for them they started with an NTSC SNES and had problems switching to 50Hz modes (as a result, said SNES was always emitting NTSC color modulation regardless of vsync rate)


Yeah it's a CRT I'm using. It handles 60hz on the GameCube etc. I can try make an RGB cable and see if that's the problem but at the minute I only have one 3 way switch. If I wire pin 4 to the middle of the switch with pin 111 I'm assuming that's a bad idea so I'll have to get a second switch before trying this. I was thinking if I use one switch I'll just have pal 50hz or region lockout mod 60hz without the option to use pal 60hz but I'm thinking them 2 wires crossing just seems like it might go wrong.


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PostPosted: Sat Jan 27, 2018 7:02 pm 
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"jumps" implies something funny with vsync also.

Can you see some kind of diagonal or checkerboard lines in the black-and-white video?


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PostPosted: Sat Jan 27, 2018 7:08 pm 
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lidnariq wrote:
"jumps" implies something funny with vsync also.

Can you see some kind of diagonal or checkerboard lines in the black-and-white video?


I'm seeing the image3 or 4 times across and moving down slowly with black horizontal lines. Here's a picture of what it looks like.

https://s14.postimg.org/7fbia5nb5/20180128_020507.jpg


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PostPosted: Sat Jan 27, 2018 7:27 pm 
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Oh, man. Uh, there's no hsync lock there, Looks like it's not even drawing at the correct 15.7ish kHz hsync rate.

The NTSC SNES starts with a 6×NTSC (i.e. 39.375MHz × 6 ÷ 11) crystal and derives everything from that; in contrast the PAL SNES ultimately operates at PAL×24÷5, from whatever provenance. (Nocash says there's a bit of silicon to generate both this clock and the actual PAL colorburst frequency at the same time in the 3-chip model)

If changing that pin means that the SNES now expects a ≈22MHz crystal instead of a ≈18MHz one, that could explain the symptoms?

Any chance you could listen to the video output and check if there's a conspicuous whine at 13kHz instead of the intended 15.6kHz ?


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PostPosted: Sat Jan 27, 2018 7:42 pm 
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lidnariq wrote:
Oh, man. Uh, there's no hsync lock there, Looks like it's not even drawing at the correct 15.7ish kHz hsync rate.

The NTSC SNES starts with a 6×NTSC (i.e. 39.375MHz × 6 ÷ 11) crystal and derives everything from that; in contrast the PAL SNES ultimately operates at PAL×24÷5, from whatever provenance. (Nocash says there's a bit of silicon to generate both this clock and the actual PAL colorburst frequency at the same time in the 3-chip model)

If changing that pin means that the SNES now expects a ≈22MHz crystal instead of a ≈18MHz one, that could explain the symptoms?

Any chance you could listen to the video output and check if there's a conspicuous whine at 13kHz instead of the intended 15.6kHz ?


Yeah it makes a high pitched squealing noise actually. So the problem here is going to likely be that I'll have to somehow source an NTSC crystal to complete this mod?


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PostPosted: Sat Jan 27, 2018 8:09 pm 
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Do check the specific frequency. A random PC microphone and some software that can generate a spectrogram (like Audacity) would be sufficient. (If you had an oscilloscope that'd be even better, but most people don't)


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PostPosted: Sat Jan 27, 2018 8:35 pm 
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lidnariq wrote:
Do check the specific frequency. A random PC microphone and some software that can generate a spectrogram (like Audacity) would be sufficient. (If you had an oscilloscope that'd be even better, but most people don't)


It seems to be picking up 13khz and 18khz when I switch it to 60hz along with the 15.6ish khz. When I switch back to 50 it picks up just the 15.6ish one on it's own as expected.


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PostPosted: Sat Jan 27, 2018 8:43 pm 
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Huh. Yeah, ok, based on the available evidence my best guess is that it needs a 6xNTSC crystal instead of a 4xPAL crystal.

4.43361875 MHz × 4 ÷ 4 ÷ 341 = 13002Hz
13002 Hz ÷ 262 = 49.625Hz ?

You said you usually have a vertical lock, just not a horizontal one?


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PostPosted: Sat Jan 27, 2018 8:59 pm 
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lidnariq wrote:
Huh. Yeah, ok, based on the available evidence my best guess is that it needs a 6xNTSC crystal instead of a 4xPAL crystal.

4.43361875 MHz × 4 ÷ 4 ÷ 341 = 13002Hz
13002 Hz ÷ 262 = 49.625Hz ?

You said you usually have a vertical lock, just not a horizontal one?


This is exactly what I'm seeing https://youtu.be/mBBDJNZI9Ns


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PostPosted: Sat Jan 27, 2018 9:13 pm 
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Ok, no vertical lock but it's certainly close to whatever frequency the TV naturally wants to run at.

The scanline-to-scanline drift moves to the right, i.e. it's too slow, so that makes me a little more confident about the choice of clock.


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PostPosted: Sat Jan 27, 2018 9:18 pm 
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I'll have a look at the FC twin I have in the morning since the snes portion of that is broken anyway. It's a 60hz nes with bad colours basically. I'll see if it has the right crystal but either way I think I'm gonna need a switch with 6 connections so it can choose the xtal and framerate together. I don't have sound either but I think this tv just doesn't have sound unless the picture locks on.


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PostPosted: Sat Jan 27, 2018 9:22 pm 
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Are you using the RF modulator or the standard A/V port? If the latter, you should be able to plug in the red/white cables into an external sound system, or even headphones.

Krzysiobal found that he was able to leave one side of both crystals permanently attached in a region-switchable famiclone.


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PostPosted: Sat Jan 27, 2018 9:29 pm 
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lidnariq wrote:
Are you using the RF modulator or the standard A/V port? If the latter, you should be able to plug in the red/white cables into an external sound system, or even headphones.

Krzysiobal found that he was able to leave one side of both crystals permanently attached in a region-switchable famiclone.


Yeah I have pc speakers that take the rca connections so I'll try that first thing tomorrow. I don't even mind if I have to break the FC twin it's basically very cheaply made anyway and it's one of them crappy black spot IC's it uses that you see in extremely cheaply made electronics.


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