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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Thu Dec 05, 2019 3:25 am 


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maxtherabbit wrote:
does this occur on all SNES if you feed the encoder dejittered sync? or is it just a 1-chip specific issue?

got curious and answered my own question - I hooked up my SHVC-CPU-01 with the encoder being fed dejittered sync from the CPLD:

on Y/C and CBVS there is a slight discoloration for the first ~10 scanlines at the top of the image

somewhat subtle under most conditions but certain images really make it stand out more


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Thu Dec 05, 2019 3:36 am 


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marqs wrote:
For 1) you need to disconnect BH7236AF video encoder pin 6 and connect that to snes_dejitter CPLD pin 11 which provides clean subcarrier. I think there was some discussion about this a few pages back. The latest firmware from nes-fix branch must also be installed on the board.

So we're thinking this should work for SNES as well? Connect CPLD pin 11 directly to the appropriate subcarrier input pin on the encoder?


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Thu Dec 05, 2019 11:44 am 



Joined: 08 Mar 2017
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If you wonder about conditioning the subcarrier signal first, then yeah, this is something to look into.
Conditioning the signal will affect the final image quality somewhat.

But for just testing, a direct connection will work.
Make the wire short and don't route it along other analog video traces.
Thinking about it, maybe do add a 100 Ohm series resistor close to the subcarrier output on the CPLD (just for protection).

If it works, it may be a good idea to replicate the original subcarrier conditioning that's on the SNES board.
This is probably going to be a few attenuation resistors, maybe an AC coupling capacitor, maybe a capacitor to ground as a filter.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Thu Dec 05, 2019 3:13 pm 


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rama wrote:
If you wonder about conditioning the subcarrier signal first, then yeah, this is something to look into.
Conditioning the signal will affect the final image quality somewhat.

But for just testing, a direct connection will work.
Make the wire short and don't route it along other analog video traces.
Thinking about it, maybe do add a 100 Ohm series resistor close to the subcarrier output on the CPLD (just for protection).

If it works, it may be a good idea to replicate the original subcarrier conditioning that's on the SNES board.
This is probably going to be a few attenuation resistors, maybe an AC coupling capacitor, maybe a capacitor to ground as a filter.

That's exactly what I was thinking. I was actually thinking it would be best to inject the dejittered subcarrier at R29 as shown on this schematic. It's south of the encoder
Spoiler: show
Image


That would preserve all the filtering, and provide an easy attachment point without requiring a pin lift.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Thu Dec 05, 2019 3:52 pm 



Joined: 08 Mar 2017
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Hm, no, I was more thinking of the circuit for an S-RGB (late model 1, all 1Chip SNES).
The one for the original SNES S-ENC has a lot of stuff going on that may be more than just some filtering.
I would go with a more direct connection there.

We need to consider that the CPLD probably has a different output impedance and drive strength than the orginal SNES PPU, so the original circuit should be more of a guideline.
Whatever that S-ENC circuit is, that's for the experts to tell :p

Edit:
Okay, if you're installing this to an S-ENC, then *do* use R29.
The circuit may be providing a phase shifted copy of the subcarrier to another input pin, and this may be required for the S-ENC to work.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Fri Dec 06, 2019 12:06 pm 


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Also remember to try with nes-fix fw since the default image does not yet have subcarrier added on pin 11.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Sat Dec 07, 2019 12:16 am 



Joined: 28 Nov 2019
Posts: 6
Hey guys,

Thanks for your thoughts on this. I'm happy to test any of your possible solutions. I'm working with two NTSC 1-Chip systems: One full size, one Jr. I'll go ahead and program them with the NES-Fix version in anticipation. :)

I wish I could help but I am only following a little of what you are discussing.

Thanks,

Heather


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Sat Jan 04, 2020 8:46 am 



Joined: 29 Apr 2016
Posts: 202
Should the subcarrier be conditioned for NESRGB 1.x installs as well?

On my NESRGB board, I disabled the original subcarrier by removing a series resistor and capacitor to ground. The dejitter CPLD subcarrier is directly connected to the BH7236AF video encoder's pin 6.

I haven't tested this yet, as my NES needs other work before I close it back up. But is it okay like this?


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Sat Jan 04, 2020 12:23 pm 



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https://media.digikey.com/pdf/Data%20Sh ... 240AKV.pdf
Quote:
Color subcarrier input terminal. Input the sine-wave or pulse-wave (duty 50%) according to a required output format (3.579545MHz for NTSC, 4.433619MHz for PAL). Moreover, this input must not exceed more than power supply level and less than ground level.

Sounds like a direct connection works.
I'd still add a little series resistance that helps attenuate higher frequencies and protects the input from overshoots.
I'm not good calculating good values here, but around 100 Ohm is probably doing the job.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Sat Jan 04, 2020 4:26 pm 



Joined: 04 Jan 2020
Posts: 1
Hi all,
I’m having some issues with my super Famicom and the OSSC.
It seems that the dejitter mod could solve the problem.

I have the SNS-CPU-RGB-01 board version. I haven’t seen any installation tutorial on the GitHub page for that version. There is something for the SNS-CPU-APU version.
Correct me if I’m wrong but those two pcb versions seem to be the same.
Should I follow the installation procedure of the APU for my RGB-01 revision?

Thanks!


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Sun Jan 05, 2020 12:09 am 



Joined: 29 Apr 2016
Posts: 202
Thanks. I took a picture of my NESRGB before I removed the resistor, and see that it was a 2kΩ (code 30B). Perhaps I should put this back in. Unfortunately I don't know what the capacitor value was.

Edit: I guess the question is, how similar is the dejitter subcarrier to the NESRGB's? Would the dejitter subcarrier work best with the same resistor/cap values?


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Sun Jan 05, 2020 3:24 am 



Joined: 29 Apr 2016
Posts: 202
I emailed Tim, and he answered that the capacitor to ground on the NESRGB's subcarrier line is 27 pF 5% NP0 0603.

So that's a 2kΩ series resistor and a 27 pF capacitor to ground, in case that helps anyone else.


Last edited by copy on Mon May 04, 2020 12:53 am, edited 1 time in total.

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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Wed Jan 08, 2020 4:17 pm 


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Has anyone on this board tried using Tim Worthington's RGB mod plus the YPbPr transcoder board and feed that into the OSSC? Wondering if the jitter only effects RGB or is it YPbPr as well.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Wed Jan 08, 2020 9:41 pm 


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geiger9 wrote:
Has anyone on this board tried using Tim Worthington's RGB mod plus the YPbPr transcoder board and feed that into the OSSC? Wondering if the jitter only effects RGB or is it YPbPr as well.

haven't tried that, but the jitter was still a problem using a SNES with HD retrovision component cables


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Sun Mar 15, 2020 7:41 pm 


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marqs: I just stuck a scope probe on pin 11 of the CPLD on my dejitter board. I'm getting a 5Vpp square wave, that means I have the updated NES-fix version that can be connected to the encoder to fix the discoloration problem, correct?


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Sun Mar 15, 2020 10:40 pm 


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maxtherabbit wrote:
marqs: I just stuck a scope probe on pin 11 of the CPLD on my dejitter board. I'm getting a 5Vpp square wave, that means I have the updated NES-fix version that can be connected to the encoder to fix the discoloration problem, correct?
Where did you get that board and are you installing it on NES or SNES?


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Sun Mar 15, 2020 10:45 pm 


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marqs wrote:
maxtherabbit wrote:
marqs: I just stuck a scope probe on pin 11 of the CPLD on my dejitter board. I'm getting a 5Vpp square wave, that means I have the updated NES-fix version that can be connected to the encoder to fix the discoloration problem, correct?
Where did you get that board and are you installing it on NES or SNES?

the board is already installed in my SNES, I got it from Arithmus on this forum

I don't know what revision firmware he flashed to it, so that's why I decided to probe pin 11 (since it should be a constant logic state without the subcarrier commit, correct?)

I supplied dejittered C-sync to the encoder when I did my initial install (and documented it here) now I noticed that I'm having the same top-of-screen discoloration problems with CVBS and Y/C as the people who reported them on NES. It is all posted at the top of this page of this thread


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Mon Mar 16, 2020 10:01 am 


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maxtherabbit wrote:
I don't know what revision firmware he flashed to it, so that's why I decided to probe pin 11 (since it should be a constant logic state without the subcarrier commit, correct?)

I supplied dejittered C-sync to the encoder when I did my initial install (and documented it here) now I noticed that I'm having the same top-of-screen discoloration problems with CVBS and Y/C as the people who reported them on NES. It is all posted at the top of this page of this thread
I assume it's flashed with the nes-fix fw then. The subcarrier addition has been included to snes branch as well but it's not pushed to repo since it's not verified yet. Most likely the nes-fix version will work ok on your snes too so feel free to try the subcarrier from the CPLD.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Mon Mar 16, 2020 3:14 pm 


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maxtherabbit wrote:
marqs wrote:
maxtherabbit wrote:
marqs: I just stuck a scope probe on pin 11 of the CPLD on my dejitter board. I'm getting a 5Vpp square wave, that means I have the updated NES-fix version that can be connected to the encoder to fix the discoloration problem, correct?
Where did you get that board and are you installing it on NES or SNES?

the board is already installed in my SNES, I got it from Arithmus on this forum

I don't know what revision firmware he flashed to it, so that's why I decided to probe pin 11 (since it should be a constant logic state without the subcarrier commit, correct?)

I supplied dejittered C-sync to the encoder when I did my initial install (and documented it here) now I noticed that I'm having the same top-of-screen discoloration problems with CVBS and Y/C as the people who reported them on NES. It is all posted at the top of this page of this thread

All SNES Dejitter mods I have sold have been flashed with the SNES branch of the Dejitter firmware. You can experiment with the NES fix branch of the firmware if you like. Ive been recently started testing a version of the SNES firmware that Marqs provided to me that has the sub carrier on pin 11 and so far it seems to be working great. I've only tested it on a SNES mini so far, but I'll be trying it on other SNES models as I have time.
_________________
plus ça change,
plus c'est la même chose,
The more that things change,
The more they stay the same.- RUSH- Circumstances

I install and sell mods at arthrimus.com | SNES RGB Bypass+Dejitter available now! | Watch me live stream my work on YouTube


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Mon Mar 16, 2020 6:20 pm 


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Arthrimus wrote:
All SNES Dejitter mods I have sold have been flashed with the SNES branch of the Dejitter firmware. You can experiment with the NES fix branch of the firmware if you like. Ive been recently started testing a version of the SNES firmware that Marqs provided to me that has the sub carrier on pin 11 and so far it seems to be working great. I've only tested it on a SNES mini so far, but I'll be trying it on other SNES models as I have time.

Hmmm well that's curious. I wonder what this signal I'm seeing on pin 11 is? Cause I bought this board from you like a year ago so it's not recent...


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Tue Mar 17, 2020 3:54 am 


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maxtherabbit wrote:
Arthrimus wrote:
All SNES Dejitter mods I have sold have been flashed with the SNES branch of the Dejitter firmware. You can experiment with the NES fix branch of the firmware if you like. Ive been recently started testing a version of the SNES firmware that Marqs provided to me that has the sub carrier on pin 11 and so far it seems to be working great. I've only tested it on a SNES mini so far, but I'll be trying it on other SNES models as I have time.

Hmmm well that's curious. I wonder what this signal I'm seeing on pin 11 is? Cause I bought this board from you like a year ago so it's not recent...

I'm really not sure. I only flash the NES fix firmware if someone specifically asks for it.
_________________
plus ça change,
plus c'est la même chose,
The more that things change,
The more they stay the same.- RUSH- Circumstances

I install and sell mods at arthrimus.com | SNES RGB Bypass+Dejitter available now! | Watch me live stream my work on YouTube


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Tue Mar 17, 2020 4:04 am 


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well I went back and probed it again - it's definitely not the subcarrier - the scope's builtin frequency counter puts it around 350kHz


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Tue Mar 17, 2020 12:09 pm 


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maxtherabbit wrote:
well I went back and probed it again - it's definitely not the subcarrier - the scope's builtin frequency counter puts it around 350kHz
Unused pins on that CPLD have unspecified output so you may see weird signal when the pin is not mapped to subcarrier output.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Tue Mar 17, 2020 2:14 pm 


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OK well if I have to flash it anyway, is there any advantage to using the SNES version with sub carrier or should I just grab the latest nes-fix from git?


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Tue Mar 17, 2020 2:24 pm 


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maxtherabbit wrote:
OK well if I have to flash it anyway, is there any advantage to using the SNES version with sub carrier or should I just grab the latest nes-fix from git?
I just uploaded the updated SNES version to github as it has been tested with SNES mini at least - essentially nothing should have changed aside from the addition of subcarrier output. I recommend using that with SNES since CSYNC_i capture edge was changed in NES version to accommodate slight IO timing difference between the systems.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Tue Mar 17, 2020 2:34 pm 


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marqs wrote:
maxtherabbit wrote:
OK well if I have to flash it anyway, is there any advantage to using the SNES version with sub carrier or should I just grab the latest nes-fix from git?
I just uploaded the updated SNES version to github as it has been tested with SNES mini at least - essentially nothing should have changed aside from the addition of subcarrier output. I recommend using that with SNES since CSYNC_i capture edge was changed in NES version to accommodate slight IO timing difference between the systems.

cool, thanks


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Thu Mar 19, 2020 1:21 am 



Joined: 15 Feb 2014
Posts: 39
Hey what's up guys. So I recently installed Arthrimus's combined dejitter and rgb and now I'm not getting any video at all. I'm not sure what could be wrong, I wouldn't even know where to troubleshoot. This snes was working fine before with Voultar's RGB. I'm thinking it was the dejitter part that's not working properly? I soldered everything myself, including the dejitter board. I can show pictures too. I just need help figuring out where to start troubleshooting. I've done so many modifications, and I'm overwhelmed as to where I should find a starting point. Thanks for any help. Also, if this is the wrong thread to post this, I'm sorry and I can post it elsewhere, if needed.

https://imgur.com/a/mkLiDob


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Fri Mar 27, 2020 9:03 am 



Joined: 27 Oct 2017
Posts: 2
Hi Guys,

i have problems with my OSSC and bought the DeJitter from VGP

Any tips on the installation on a SNES MINI which already has Bortis Ultimate Switchless and RGB Bypass?


Rgds Dario


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Tue Mar 31, 2020 4:31 pm 



Joined: 01 Mar 2018
Posts: 555
Are there any reliable installation pics for the boards? Mine arrived today and just realized RetroModWiki is down. I can probably try to follow the written instructions on Github, but pictures would sure be helpful.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Thu Apr 02, 2020 1:07 pm 



Joined: 21 Aug 2016
Posts: 640
ldeveraux wrote:
Are there any reliable installation pics for the boards? Mine arrived today and just realized RetroModWiki is down. I can probably try to follow the written instructions on Github, but pictures would sure be helpful.


The wiki was moved to a different URL so it could be hosted for free. NES install is here, but SNES is also still available. https://retromods.game.blog/nes-famicom ... d-install/


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