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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Sun Dec 16, 2018 5:13 pm 



Joined: 02 Sep 2016
Posts: 118
Thanks very much for the information.

If I have any more questions I'll post another reply. I'm going to be using an NESRGB board in the NES (with the dejitter board) and Voultar's SNES RGB amp in my 1CHIP03 (with the CSYNC lines restored on the motherboard).


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Wed Dec 19, 2018 7:26 pm 



Joined: 02 Sep 2016
Posts: 118
Does anybody have any pictures of wiring a shielded coax cable to the MCLK_o and NES PPU?

Even the smaller (RJ59?) coax cable is very thick and it seems very difficult to wire onto the small pads/pins unless I'm not understanding something?

Image

Also, is it recommend to use any coax wires for the SNES dejitter mod?


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Wed Dec 19, 2018 8:49 pm 



Joined: 08 Mar 2017
Posts: 729
"Coax" became a term most often associated with the kind of cable you pictured.
The term just means that you have an inner conductor for the signal, and an outer conductor that shields it.
The cable can be much thinner, and for this task, it should probably be the smallest type you can find.

Make it a small and flexible cable and keep it short :)


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Thu Dec 20, 2018 1:26 am 



Joined: 02 Sep 2016
Posts: 118
Thanks for the information.

Do you see anything on Amazon (or Mouser/Digikey?) that fits the criteria? It seems difficult to find...


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Thu Dec 20, 2018 1:39 am 


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sofakng wrote:
Thanks for the information.

Do you see anything on Amazon (or Mouser/Digikey?) that fits the criteria? It seems difficult to find...

There are many types of coax smaller than rg-59

Search for "mini coax" :wink:


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Thu Dec 20, 2018 2:26 am 



Joined: 02 Sep 2016
Posts: 118
Great, thanks! I've order this one from Amazon: C2G 27227 Velocity Mini-Coax F-Type. Supposedly it has 26 AWG wires inside.

Should I use a shielded cable (coax) for the SNES MCLK_o line too?


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Fri Dec 21, 2018 6:45 pm 



Joined: 02 Sep 2016
Posts: 118
Sorry, one more question about the NES csync output and termination (ie. resistors).

The Retro Modding Wiki instructions say to connect NESRGB CS# (J8 open; TTL sync output) to the Dejitter CSYNC_i pad.

If my SCART cable doesn't have a 470 ohm resistor, do I need to add one between the dejitter CSYNC_o and the multi-av output connector? The dejitter GitHub page says it outputs 2.5vpp unterminated and ~1.1vpp @ 75 ohm when terminated?

Similar question for my SNES. I'm using Voultar's RGB amp with my 1CHIP-03 (with csync restored on motherboard because 1CHIP-03 was missing parts for csync). If my SCART cables does have the 470 ohm resistor, then I'm guessing I don't need to do anything here?


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Fri Dec 21, 2018 7:04 pm 



Joined: 21 Aug 2016
Posts: 448
sofakng wrote:
Sorry, one more question about the NES csync output and termination (ie. resistors).

The Retro Modding Wiki instructions say to connect NESRGB CS# (J8 open; TTL sync output) to the Dejitter CSYNC_i pad.

If my SCART cable doesn't have a 470 ohm resistor, do I need to add one between the dejitter CSYNC_o and the multi-av output connector? The dejitter GitHub page says it outputs 2.5vpp unterminated and ~1.1vpp @ 75 ohm when terminated?

Similar question for my SNES. I'm using Voultar's RGB amp with my 1CHIP-03 (with csync restored on motherboard because 1CHIP-03 was missing parts for csync). If my SCART cables does have the 470 ohm resistor, then I'm guessing I don't need to do anything here?


So a few things. That coax cable you linked to before is going to be huge. I didn't use any coax cable on my install and I have had no issues. I just used some high-quality wire from a Mogami mic snake because I happened to have it lying around, but that's really the main thing is to make sure you are using quality wire.

Regarding the NES, I am not entirely sure what you want to do there, but it does seem like having the resistor inline is not a bad idea. I used a standard SNES cable in my install as that was kinda the point (for me) of using the multiout, so I can't really speak to that.

With the SNES, I believe you are good to go there but someone can correct me if I am wrong.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Fri Dec 21, 2018 9:44 pm 


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Location: Finland
A cheap way to obtain a decent coax is to cut a leftover composite or audio cable. The reason why coax was mentioned only with NES is because the required distance is longer, making the clock line more prone to EMI & noise. I haven't either had issues with an unshielded cable but there was a few reports some pages back where certain setups (e.g. specific games using Everdrive) apparently generated noise bad enough to infer glitches on clock line until it was shielded.

As for CSYNC_o, you may add the series resistor but it's not strictly necessary, 1.1Vpp is still a safe level for 75ohm terminated video/sync inputs.


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 Post subject: NES/SNES 240p dejitter mod
PostPosted: Fri Dec 28, 2018 2:31 pm 


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Joined: 17 Jan 2016
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Maybe a stupid question but if I have a sync on Luma cable, will this mod work for me as I am not using csync


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Sat Dec 29, 2018 1:08 am 


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Joined: 07 May 2018
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Location: Escondido, CA, USA
You have to either:

route the dejitter board output to the luma pin. Possibly sever the circuit to that pin, if it's a console with s-video enabled. Of course, that will disable s-video.

Or

Rewire the cable, at the console end. May not be possible.

Maybe some way to inject the sync upstream into the luma circuit. The smarter guys around here will know.

Sent from my SM-G955U using Tapatalk


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Sat Dec 29, 2018 9:40 am 


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Joined: 17 Jan 2016
Posts: 248
Thanks

I have 1chip03 and a nes rgb. I am finding the documentation/instructions for installation to be a little sparse on both sides so I am very wary of starting something until I am ready. I may have to buy a csync cable


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Mon Jan 07, 2019 1:04 am 


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How would one go about installing the dejitter board alongside borti's superCIC multi-region board in a SNES Mini/Jr.? Each board has its own circuitry using a 21.47727Mhz crystal which replaces X1. The dejitter board requires the removal of c3 but the superCIC board leaves it alone.

Image
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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Tue Jan 08, 2019 5:37 pm 


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unmaker wrote:
How would one go about installing the dejitter board alongside borti's superCIC multi-region board in a SNES Mini/Jr.? Each board has its own circuitry using a 21.47727Mhz crystal which replaces X1. The dejitter board requires the removal of c3 but the superCIC board leaves it alone.
You should be able to put snes_dejitter board in between there. First disconnect that green wire from SNES mainboard and connect it to MCLK_EXT_i of snes_dejitter instead. Then hook up Mode pin of superCIC board to snes_dejitter CLK_SEL_i. Rest of the snes_dejitter signals you should wire as usual, and you can probably leave C3 there as is.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Thu Jan 10, 2019 9:46 am 


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marqs wrote:
unmaker wrote:
How would one go about installing the dejitter board alongside borti's superCIC multi-region board in a SNES Mini/Jr.? Each board has its own circuitry using a 21.47727Mhz crystal which replaces X1. The dejitter board requires the removal of c3 but the superCIC board leaves it alone.
You should be able to put snes_dejitter board in between there. First disconnect that green wire from SNES mainboard and connect it to MCLK_EXT_i of snes_dejitter instead. Then hook up Mode pin of superCIC board to snes_dejitter CLK_SEL_i. Rest of the snes_dejitter signals you should wire as usual, and you can probably leave C3 there as is.


I appreciate the reply. This is actually not my install. I wanted to know if the two boards were compatible with each other before trying this out.
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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Fri Jan 11, 2019 8:25 am 



Joined: 05 Jul 2016
Posts: 31
I would appreciate if you can send some detailed pictures in this thread after you have done the modding? Same thing needs to be done for my console.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Sat Jan 12, 2019 2:23 am 


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Anyone here successfully installed a disable switch for the version 1.3 board (for NTSC system)?

According to the GitHub, the last paragraph under FAQ states:

Quote:
Is it possible to disable de-jitter functionality after installation?
When the board is installed so that MCLK_EXT_i and CLK_SEL_i are not used, a simple bypass can be added without firmware modifications. To do that, connect MCLK_EXT_i to CPLD pin 34 (MCLK_XTAL_o) and add a ON-OFF switch that connects MCLK_SEL_i to 5V.


2 questions:
1) CPLD pin 34 is the pin that leads to R7 pads on the version 1.3 PCB. Is that correct?
2) Is CLK_SEL_i same as MCLK_SEL_i? Was the later a typo on the quoted FAQ?


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Sat Jan 12, 2019 4:12 pm 


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BuffaloWing wrote:
2 questions:
1) CPLD pin 34 is the pin that leads to R7 pads on the version 1.3 PCB. Is that correct?
2) Is CLK_SEL_i same as MCLK_SEL_i? Was the later a typo on the quoted FAQ?
Yes and yes.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Sun Jan 13, 2019 2:03 pm 


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Is it possible to use the dejitter board on a SNES 1CHIP and output dejittered Composite/S-Video as well as 75ohm CSYNC? Perhaps by lifting the S-RGB video encoder CSYNC input (pin 7) and connecting the dejitter boards CSYNC input and output to both pad and pin? Or would the dejitter board CSYNC levels not be suitable for this?
(All my SCART cables are wired for sync on luma, and although I could rewire them to use MULTI OUT pin 3 this seems risky as I sometimes switch between PAL/NTSC SNES systems, and stock PAL systems have +9-12V on the same pin as CSYNC on NTSC systems)

Also, is anyone working on a design that combines the dejitter board with the 1CHIP 50/60Hz board?
https://oshpark.com/shared_projects/Brpg2thK
Just thought it would make for an easier installation with less wires.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Mon Jan 14, 2019 12:52 am 


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Joined: 02 Feb 2016
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Thanks for the confirmations.

marqs wrote:
BuffaloWing wrote:
2 questions:
1) CPLD pin 34 is the pin that leads to R7 pads on the version 1.3 PCB. Is that correct?
2) Is CLK_SEL_i same as MCLK_SEL_i? Was the later a typo on the quoted FAQ?
Yes and yes.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Mon Jan 14, 2019 4:33 am 


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Decoryah wrote:
I would appreciate if you can send some detailed pictures in this thread after you have done the modding? Same thing needs to be done for my console.


No problem. I just don't know when that will be as I don't even have the parts yet.
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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Mon Jan 14, 2019 5:17 pm 


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Link83 wrote:
Is it possible to use the dejitter board on a SNES 1CHIP and output dejittered Composite/S-Video as well as 75ohm CSYNC? Perhaps by lifting the S-RGB video encoder CSYNC input (pin 7) and connecting the dejitter boards CSYNC input and output to both pad and pin? Or would the dejitter board CSYNC levels not be suitable for this?
(All my SCART cables are wired for sync on luma, and although I could rewire them to use MULTI OUT pin 3 this seems risky as I sometimes switch between PAL/NTSC SNES systems, and stock PAL systems have +9-12V on the same pin as CSYNC on NTSC systems)

It's possible like you said, but for lifted S-RGB pin 7 you should tap c-sync right from snes_dejitter CPLD (pin 15) instead of CSYNC_o pad which is after a transistor driver and series resistor. If you are planning to use the setup with OSSC, it's also possible to leave S-RGB as is and just increase H-PLL post-coast to ignore the short scanline and the canceling long scanline followed by it (as seen on S-RGB input after the mod).


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Mon Jan 28, 2019 9:08 pm 


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Joined: 01 Sep 2018
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Location: Wales
Hi again, after a few months of not using my AV Famicom I started using it again a few days ago. There's this really weird issue I'm experiencing where after a minute or 2 of being on, certain things on screen start to flicker. it's not like bad contacts (I cleaned my cart thoroughly with isopropyl alcohol, plus it's happening in loads of games) as it's not the entire screen becoming corrupted, rather one or two things on screen have random white or black pixels appear in them, although it seems to be specific things meaning it's not video interference. For example see the images of Wild Gunman below, it always happens in the rock mountain in the background. It's hard to show in images as only one or two pixels appear at once. In a video they rapidly flicker. There's a link to a google drive with some videos of it happening too.

Now it could be a few things;
1) Dirty contacts on the console (never seen any bad contact cause this though, plus it's a top loader not a front loader so less likely to have issues)
2) The Dejitter mod (likely as it's involved with he CPU and PPU)
3) The NESRGB board (maybe)
4) Just the console itself

thought I'd ask here first, but I'll try the NESRGB thread next if I have no luck.
Any one have any advice? If not I could try redoing the dejitter install (again)



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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Mon Jan 28, 2019 11:43 pm 



Joined: 21 Aug 2016
Posts: 448
Is your dejitter mod configured for NES vs SNES? Definitely makes a difference over time.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Mon Jan 28, 2019 11:48 pm 


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Location: Wales
Yes it was bought pre flashed from VGP. The games still work, but its very annoying and I'm afraid of leaving the console running for more than a couple of minutes.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Tue Jan 29, 2019 12:49 am 


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It sounds like you might have one of the NESRGB batches that have a fake voltage regulator as described on this page:-
http://etim.net.au/nesrgb/background_fault/index.htm
Here is an example video of one of the possible symptoms:-
https://www.youtube.com/watch?v=97b3vj7JPiM
If this is the problem the proper way to fix it is to replace the voltage regulator with a genuine part.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Tue Jan 29, 2019 3:09 am 


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No I've checked, the serial number isn't the fake one. It's not a band of interference, more a glitch affecting specific graphics at a time. For instance in that video I posted, you can see it only ever affects the mountain in the background, so it's more like data corruption due to an issue with the clock line (or something) than video noise on the screen.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Thu Jan 31, 2019 4:07 pm 


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Location: Escondido, CA, USA
Just a heads up to anyone that is getting some noise in the video after doing the dejitter mod. I was getting this, and it turns out that routing the csync_i connection from S-RGB pin 7, from top of board to bottom of board, was the cause. There is a via that you can tap on the solder side of the board, which connects to S-RGB pin 7. this eliminates the need to route the wire on a much longer path, and for me, it elminated the noise.

The via to S-RGB pin 7 is to the left of R1, in line with the via points that are recommended for restoring RGB output. Use your multimeter to find it.

This is true for SNES Mini/jr. models. Not sure about any others.

Thanks to Goenitz_NYC for sending pics of his installation so I could figure out where I was going wrong.


Last edited by NoAffinity on Thu Jan 31, 2019 4:32 pm, edited 1 time in total.

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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Thu Jan 31, 2019 4:34 pm 



Joined: 21 Aug 2016
Posts: 448
Yeah, that's what I did in my install. Way easier since the via is already there anyway.


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 Post subject: Re: NES/SNES 240p dejitter mod
PostPosted: Mon Feb 04, 2019 1:33 am 


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Location: Seattle, WA
I have a 1chip-01 SNES outfitted with a v1.2 dejitter board and Voultar's v.79 RGB bypass board. CSYNC_i is connected to the via that routes to pin 155 of the S-CPUN (and to pin 7 on the stock encoder). CSYNC_o is connected to the CS pad on the RGB bypass board. This all works fine, but does drop sync briefly once every few hours of gameplay. On a whim, I decided to check the sync line under load, and found that it's < 200mVpp, which I'm pretty sure is out of spec. Might explain the occasional sync drops.

I'm using a cable with no resistor on the sync line, so I think I'll short the TTL jumper on Voultar's board and slap a 330Ω resistor in the cable. That should be solidly in spec. I suppose I could also wire sync directly to the multi-out, but ~1.1Vpp seems a little high.

Dunno if this will help anyone else, but it's something to be aware of at least.


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