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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Tue Jun 05, 2018 10:56 pm 



Joined: 21 Aug 2016
Posts: 201
Ah. I will have someone else update it then :) Once I get it all back I'll post my results. You're welcome to take the pictures and add to your guides if you want.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Wed Jun 06, 2018 7:18 pm 


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Joined: 20 Sep 2008
Posts: 310
Location: Ioannina , Greece
marqs wrote:
Which multisync monitors are you using and are you feeding sync to a TTL sync input? LM1881 doesn't help with sync jitter, and I doubt your problem is related to that. However, LM1881 sync output is 5Vpp while c-sync level (to unterminated input) of SNES is 2.4Vpp, which is still technically TTL but possibly not high enough for some monitors' sync inputs..


EIZO Flexscan 8060S
Quadram MS1422 (clone of original NEC multiscan monitor I've been told)
dualsync Microvitec M1438 (this one is analog-only 15~40khz , the 2 above have also digital function to accomodate cga/ega modes)

Interesting what you say about the output voltage, without passing c-sync from LM18881 I get an image without sync: a mess.
I also found that the M1438 doesn't like the md1 c-sync (directly from the encoder) and indeed passing that through the LM1881 moves the upper part of the screen to the right.

Currently investigating md1 RGB bypass, I want to use this one: https://oshpark.com/shared_projects/KiETPmh8 but I have no idea if it is good.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Sat Jun 09, 2018 6:06 am 



Joined: 02 Jan 2016
Posts: 57
Thanks to Arthrimus for the PCB

Spoiler: show
Image


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Sun Jun 10, 2018 12:45 pm 



Joined: 29 Apr 2016
Posts: 115
Can anyone who has installed this post what kind of TV they have? I'm just curious to see which TVs have confirmed compatibility improvements after the mod. (Crossing my fingers that it will help my X900E.)


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Sun Jun 10, 2018 1:05 pm 



Joined: 21 Aug 2016
Posts: 201
copy wrote:
Can anyone who has installed this post what kind of TV they have? I'm just curious to see which TVs have confirmed compatibility improvements after the mod. (Crossing my fingers that it will help my X900E.)


My TV is a TCL, so it was already very compatible. In my case, it just meant I could use 3x, 4x, and 5x with the SNES, too. Those already worked on other systems. If your TV works with other systems, all this mod does is bring the NES/SNES in line with those so that it works the same.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Sun Jun 10, 2018 5:15 pm 


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Joined: 02 Apr 2018
Posts: 15
Location: Arkansas
copy wrote:
Can anyone who has installed this post what kind of TV they have? I'm just curious to see which TVs have confirmed compatibility improvements after the mod. (Crossing my fingers that it will help my X900E.)

What kind of issues does the X900E have with the SNES?
_________________
plus ça change,
plus c'est la même chose,
The more that things change,
The more they stay the same.- RUSH- Circumstances


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Sun Jun 10, 2018 7:30 pm 


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Joined: 19 Jan 2016
Posts: 205
Location: Sweden
Several reports are saying the newest Sony 4k models do not accept snes whatsoever, they simply will not sync.
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OSSC TV Compatibility report thread


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Mon Jun 11, 2018 2:34 am 



Joined: 07 May 2018
Posts: 4
Just installed a dejitter board on my SNES mini (RGB modded, of course). Thank you to ebeb for suggesting the raspberry pi can do direct jtag programming of the 1502AS. That saved me at least $30, since I already own a pi.

A couple observations:

1) I was hoping this mod would improve compatibility with elgato camlink capturing. Unfortunately, it seems to have made it worse. Previously, I could capture stable line2x and line3x. However, now line3x is also unstable. But, line2x looks really good! :)
2) This increased incompatibility with the camlink could be due to this mod apparently resulting in > 60hz signal. At least that's what the OSSC reports. I don't own a scope, to dig further on that front. The OSSC reports 60.05hz to 60.08 hz, on all of the testing I've done so far (at least 10 boots).
3) Is there any reason that the installation instructions for the SNES mini say to use S-RGB pin 7? I had the csync mod already in place, using S-RGB pin 18. I tested with snes_dejitter csync_i connected to both pins. The best indication that I saw of which might be better, was the camlink not able to properly identify the resolution with csync_i connected to S-RGB pin 7, but is able to when connected to S-RGB pin 18.

None of that is to say that this isn't a cool mod, because in fact it is very cool. Thank you to all the clever contributors and big brains that brought this to fruition.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Tue Jun 12, 2018 2:29 am 


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Joined: 02 Apr 2018
Posts: 15
Location: Arkansas
Do other 240p sources work fine? If so, I think it's probably a safe bet that the dejitter mod will fix the problem. I have 2 different capture cards that would not sync SNES video through an OSSC no matter what linemulti or passthrough mode I used, after the dejitter board it works in all modes.
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plus ça change,
plus c'est la même chose,
The more that things change,
The more they stay the same.- RUSH- Circumstances


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Tue Jun 19, 2018 12:02 am 



Joined: 21 Aug 2016
Posts: 201
The SNES normally runs higher than 60 Hz, this just stabilizes it. And in my mini, I just grabbed sync off a via underside of the motherboard, same place Voultar grabs it from with his mods. The via is connected to pin 7, so it's basically the same thing. Works fine for me.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Tue Jun 19, 2018 2:57 am 



Joined: 07 May 2018
Posts: 4
Thanks bigcheese. That post was from over a week ago but I guess this was my first post and needed admin approval. But anyway I got help on the vgp forums, and marqs was gracious enough to chime in. Turned out I made a few mistakes, most importantly my scart cable wired for sync on composite. I rerouted the dejitter board csync_o to pin 9 and broke the composite circuit and voila, it's working flawlessly. Capturing at line5x 1920x1200, and everything below now.

Sent from my SM-G955U using Tapatalk


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Fri Jun 22, 2018 1:33 am 



Joined: 21 Aug 2016
Posts: 201
Got this installed in my NES101 tonight and it is working great! Finally I get perfect video even at 5x on the OSSC. I'll add the guide to my wiki within the next few days. Marqs, feel free to take any of the pictures and add to your page, too.

Edit: guide completed: https://www.retromodwiki.com/wiki/NES_dejitter_mod. Big, huge thanks to Marqs for developing the mod and for helping me make sure I was doing things right. Really easy to install and it looks perfect now!


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Sat Jun 23, 2018 2:50 pm 



Joined: 29 Mar 2016
Posts: 3
Just found this thread today, I have been waiting for a few years for a mod like this!

My setup is an NES front-loader that is RGB-modded. I connect it via the JP-21 port of a Micomsoft XRGB-3. I run the XRGB-3 in line-doubler mode and output the VGA to a powered VGA splitter box with one side going directly to my CRT computer monitor and the other going to an Epiphan VGA capture device (USB 3.0). The jitter on the CRT monitor isn't too bad - I can just vertically move my image up until it is gone as it doesn't affect very far down the picture, but the capture device on the other hand - HORRIBLE. The jitter carries down roughly 1/3 of the image making it virtually un-watchable when I make recordings.

With much of the tech stuff in this thread being over my head - will this mod fix this problem for me with my setup?


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Sat Jun 23, 2018 3:06 pm 



Joined: 21 Aug 2016
Posts: 201
It should.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Sun Jun 24, 2018 6:41 pm 



Joined: 07 May 2018
Posts: 4
Not sure if this will be at all useful for anyone looking to programming their dejitter board with a pi, but thought I would post it in case someone wants/needs it. Hopefully save others some time with the openocd installing, configuration of various pieces of the pi, etc.



Tested on Pi 1 Model B+ and snes_dejiter v1.2. The complete assembled and programmed dejitter board tested on SNES Mini (SNN-CPU-01).

Download pi image here: https://drive.google.com/open?id=1iy0jj ... yIsduTYyF9
Connect 5V and ground from GPIO header to dejitter board JTAG connector before power on pi. Hot-plugging the JTAG signal lines is no problem, but hot-plugging 5V may cause a voltage error, requiring the pi to rebooted.

Flash the image file to a 16gb or larger micro sd card
Login: pi
Password: raspberry

As far as I can tell, GPIO implementation on the Pi has not changed over the various model revisions, with the exception of the base address being different on Pi 3, compared to its predecessors. /home/pi/openocd-pi.conf contains instructions for changing the base address within the file, to ensure compatibility. Openocd-pi.conf contains much useful information, including GPIO header pin assignments, for connecting to dejitter board for programming:
>sudo nano /home/pi/openocd-pi.conf

Once you have read through openocd-pi.conf and done any initial testing, connect dejitter board to GPIO header/pi, and run the following commands:

> cd /home/pi
> openocd –f openocd-pi.conf

Then proceed with the following instructions from marqs’ readme:

https://github.com/marqs85/snes_dejitte ... /README.md

3. OpenOCD auto-probing should report a TAP controller with id 0x0150203f. You can now open another terminal to interact with openocd and program the chip:
telnet localhost 4444
> svf /home/pi/snes_dejitter.svf
4. The programming procedure should finish with no error, after which you can finish installation by powering off hardware and disconnecting the programmer.

/home/pi also contains snes_dejitter_new.svf, which is the latest svf version contained at the project github page. Programming with this svf was not successful for me, and I suggest ignoring this svf file, but it is there for posterity.


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