NES/SNES 240p dejitter mod

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nosblod
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Re: NES/SNES 240p dejitter mod

Post by nosblod »

Is it possible to verify that the board was programmed correctly, before installation?

Context: I tried an USB Blaster clone for a while, gave up and found an JTAG-Arduino method, which required the SVF-file to be converted to XSVF.
The process "seems" to have worked, but I'd prefer to verify this before adding even more parts to the equation.
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marqs
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Re: NES/SNES 240p dejitter mod

Post by marqs »

Digital Dragon wrote: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.
Are you using a shielded cable for MCLK_o? If not, it might be worth trying out as it has fixed stability issues in a few NES installations.
otj wrote: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.
R9-R10 resistor divider values were updated in v1.3 PCB to produce nominal 300mV sync level with cables/mods that have 470ohm series resistor. ~1.1Vpp pure sync is also ok for video-level inputs (for reference, composite is 1Vpp) so directly soldering to multi-av should work too.
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otj
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Re: NES/SNES 240p dejitter mod

Post by otj »

marqs wrote:R9-R10 resistor divider values were updated in v1.3 PCB to produce nominal 300mV sync level with cables/mods that have 470ohm series resistor. ~1.1Vpp pure sync is also ok for video-level inputs (for reference, composite is 1Vpp) so directly soldering to multi-av should work too.
Sounds great! Many thanks for the info, and thanks for designing such a great little board. I was unable to reach 5x without it. :D
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Digital Dragon
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Re: NES/SNES 240p dejitter mod

Post by Digital Dragon »

Hey Marqs, yes I'm using a coax. It seems I may have found what my issue is, it seems it was a big problem for Jason of gametechus. If anyone has similar symptoms to what I posted check out this thread.

viewtopic.php?p=1297501#p1297501
nosblod
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Re: NES/SNES 240p dejitter mod

Post by nosblod »

nosblod wrote:Is it possible to verify that the board was programmed correctly, before installation?
Never mind, I got some extra time on my hands and actually installed the board. Works like a charm!
My unit had an SNS-CPU-GPM-01-board, but the guide for SNS-CPU-GPM-02 matched perfectly.

Thanks for all your great work marqs! <3

I did screw up and accidentally ripped the left copper pad away of R25, luckily I found the schematics and connected CSYNC_o to the lower pad of C46 instead.

One new question, would ATF1502AS-10AU44 be to slow for this? It seems easier to source in some countries. I ordered a bunch extra of the 7AU44's so I'm fine, just wondering if that should be an option for others. :)
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Digital Dragon
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Re: NES/SNES 240p dejitter mod

Post by Digital Dragon »

Ok so by removing Q1 on my AV Famicom I was able to get rid of the glitches. Turns out that shmups thread I linked to was the issue I was having. If anyone has any flickering pixels or 'snow' check that out, thanks for the help everyone :D

Also Viletim just posted on the NESRGB thread that a 2.0 NESRGB has been released as well as firmware for older NESRGB 1.X that includes the dejitter feature. So this may make the dejitter board redundant for NES and Famicoms. Kinda makes me wish I had waited, though I would have had to disconnect the clock anyway and would have lost my palette switch, so it's alright.
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monster
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Re: NES/SNES 240p dejitter mod

Post by monster »

I built the board myself, programmed it with a Raspberry Pi and installed it in my AV Famicom according to retromodwiki.com's instructions using a shielded wire. I only get grey screen when dejitter board is connected but the console is working perfectly fine using the stock crystal which I connected back for troubleshooting. I have an access to an oscilloscope and I saw that amplitude of a clock signal coming out of the dejitter board drops to around 2V pk-pk which is probably fine for the NESRGB and might be fine for the PPU but the CPU's M2 line is silent. Am I doing something wrong? Should I remove the voltage divider from the dejitter board?
leonk
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Re: NES/SNES 240p dejitter mod

Post by leonk »

FYI .. there's a new version of NESRGB with dejitter firmware.

If you have an NESRGB now, there's instructions on how to update a few components on the NESRGB to enable dejitter as well as new firmware to enable this feature.

Firmware location: https://etim.net.au/nesrgb/background_fault/
Update instructions: https://etim.net.au/nesrgb/background_f ... itter.html
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Pasky
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Re: NES/SNES 240p dejitter mod

Post by Pasky »

Anyone in the USA selling assembled boards? Rather not have a wait ordering from the UK and no time to assemble myself.
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marqs
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Re: NES/SNES 240p dejitter mod

Post by marqs »

monster wrote:I built the board myself, programmed it with a Raspberry Pi and installed it in my AV Famicom according to retromodwiki.com's instructions using a shielded wire. I only get grey screen when dejitter board is connected but the console is working perfectly fine using the stock crystal which I connected back for troubleshooting. I have an access to an oscilloscope and I saw that amplitude of a clock signal coming out of the dejitter board drops to around 2V pk-pk which is probably fine for the NESRGB and might be fine for the PPU but the CPU's M2 line is silent. Am I doing something wrong? Should I remove the voltage divider from the dejitter board?
2V is indeed way too low, it should be around 3-4V. Could you check the resistor values you've used and measure the output level when MCLK_o is not connected anywhere? Removing voltage divider altogether is not recommended since the clock line also drives NESRGB's CPLD which is not designed for 5v signal level.
nmalinoski
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Re: NES/SNES 240p dejitter mod

Post by nmalinoski »

Pasky wrote:Anyone in the USA selling assembled boards? Rather not have a wait ordering from the UK and no time to assemble myself.
If you're looking for a dejitter for the NES, the Tim Worthington's US distributor has NESRGB v2 boards in stock that have dejitter capability baked in, and there'll be a new firmware for 1.3/1.4 boards that includes it at the cost of palette selection.

If for SNES, I'm not aware of any. I'd make a post in the Wanted forum.
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Pasky
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Re: NES/SNES 240p dejitter mod

Post by Pasky »

nmalinoski wrote:
Pasky wrote:Anyone in the USA selling assembled boards? Rather not have a wait ordering from the UK and no time to assemble myself.
If you're looking for a dejitter for the NES, the Tim Worthington's US distributor has NESRGB v2 boards in stock that have dejitter capability baked in, and there'll be a new firmware for 1.3/1.4 boards that includes it at the cost of palette selection.

If for SNES, I'm not aware of any. I'd make a post in the Wanted forum.
Cool thanks.
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monster
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Re: NES/SNES 240p dejitter mod

Post by monster »

marqs wrote: 2V is indeed way too low, it should be around 3-4V. Could you check the resistor values you've used and measure the output level when MCLK_o is not connected anywhere? Removing voltage divider altogether is not recommended since the clock line also drives NESRGB's CPLD which is not designed for 5v signal level.
Voltage divider is as in BOM for ver. 1.2: 39/300 Ohm.
I measured the voltages with and without load and here's what I got:
Under load: GCLK_o: 3.36Vpk, MCLK_o: 1.5Vpk
No load: GCLK_o: 4.20Vpk, MCLK_o: 3.36Vpk
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Arthrimus
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Re: NES/SNES 240p dejitter mod

Post by Arthrimus »

Pasky wrote:Anyone in the USA selling assembled boards? Rather not have a wait ordering from the UK and no time to assemble myself.
I have a couple boards assembled right now that I could let go of. P.M. me if you are still looking.
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
sofakng
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Re: NES/SNES 240p dejitter mod

Post by sofakng »

Are there any instructions for wiring Voultar's SNES RGB AMP with Marqs dejitter board on a 1CHIP-03?

I've purchased (but not installed) the 1CHIP-03 CSYNC restorations caps/resistors as well and my SNES RGB cable has a 470 ohm resistor.

Should I also change any of the resistors on the dejitter board because it's v1.2 (and according to a post above, v1.3 has different resistors for 470 ohm cables?)
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Arthrimus
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Re: NES/SNES 240p dejitter mod

Post by Arthrimus »

sofakng wrote:Are there any instructions for wiring Voultar's SNES RGB AMP with Marqs dejitter board on a 1CHIP-03?

I've purchased (but not installed) the 1CHIP-03 CSYNC restorations caps/resistors as well and my SNES RGB cable has a 470 ohm resistor.

Should I also change any of the resistors on the dejitter board because it's v1.2 (and according to a post above, v1.3 has different resistors for 470 ohm cables?)
I've never used voultar's board but it looks like the only component in the Csync line is the resistor for 75ohm sync. You should be able to simply close the TTL jumper and wire CSYNC_o from the dejitter board directly to the CS pad on the RGB amp.
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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maxtherabbit
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Re: NES/SNES 240p dejitter mod

Post by maxtherabbit »

the CSYNC coming off of pin 100 on the S-PPU2 which is connected to CSYNC_i is at logic level, correct?
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Arthrimus
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Re: NES/SNES 240p dejitter mod

Post by Arthrimus »

maxtherabbit wrote:the CSYNC coming off of pin 100 on the S-PPU2 which is connected to CSYNC_i is at logic level, correct?
I measure 5.4Vpp on pin 100 so I'm thinking yes.
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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marqs
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Re: NES/SNES 240p dejitter mod

Post by marqs »

monster wrote:
marqs wrote: 2V is indeed way too low, it should be around 3-4V. Could you check the resistor values you've used and measure the output level when MCLK_o is not connected anywhere? Removing voltage divider altogether is not recommended since the clock line also drives NESRGB's CPLD which is not designed for 5v signal level.
Voltage divider is as in BOM for ver. 1.2: 39/300 Ohm.
I measured the voltages with and without load and here's what I got:
Under load: GCLK_o: 3.36Vpk, MCLK_o: 1.5Vpk
No load: GCLK_o: 4.20Vpk, MCLK_o: 3.36Vpk
That's quite a bit of drop under load. Did you check if Vmin was significantly above 0V which would indicate capacitive load is high enough to prevent clock signal reaching its peak voltages?
sofakng
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Re: NES/SNES 240p dejitter mod

Post by sofakng »

Is there any benefit to using coax wire for the dejitter on the SNES (1CHIP) ?

I purchased some 26 and 28 AWG coax from Mouser and I'm going to use it on the NES dejitter install but what about the SNES?

The CSYNC_i and CSYNC_o connections appear to be long wires. MCLK_o is very short though:
Image

Is there any benefit at all to using coax for these connections on this board? Non-coax is easier because I don't need to find GND points but I'd rather not open my SNES open again so I want to do this as best as possible :)
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Arthrimus
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Re: NES/SNES 240p dejitter mod

Post by Arthrimus »

I've never used coax on any SNES dejiter installs and I've installed in nearly every version there is. I think coax is mostly recommended for NES installs if I'm not mistaken.
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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LDigital
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Re: NES/SNES 240p dejitter mod

Post by LDigital »

sofakng wrote:Is there any benefit to using coax wire for the dejitter on the SNES (1CHIP) ?

I purchased some 26 and 28 AWG coax from Mouser and I'm going to use it on the NES dejitter install but what about the SNES?

The CSYNC_i and CSYNC_o connections appear to be long wires. MCLK_o is very short though:
Image

Is there any benefit at all to using coax for these connections on this board? Non-coax is easier because I don't need to find GND points but I'd rather not open my SNES open again so I want to do this as best as possible :)
Is this an image of an installer 03? If I copy yours will it work like this? Been looking for instructions on how to install on mine
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Harrumph
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Re: NES/SNES 240p dejitter mod

Post by Harrumph »

It says 1chip-01 on the board, so no
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maxtherabbit
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Re: NES/SNES 240p dejitter mod

Post by maxtherabbit »

Wanted to document my install on SHVC-CPU-01. I elected to put the dejitter board on top, to reduce wire lengths.

The primary thing that distinguishes this install will be injecting the dejittered sync back into circuit before the video encoder in the SNES, providing dejittered outputs on CVBS, Y/C and RGBS.

First, remove C5 and R6 as per marqs' instructions for SHVC-CPU-01. This severs the original xtal circuit from the CPU, PPUs and cart slot.
Spoiler
Image

Next, lift pin 100 of the PPU2, this will be our csync source to feed to CSYNC_i on the mod board.
Spoiler
Image

Next, scrape the solder resist off of the via immediately to the right of C69 :wink: this via is attached to the pad for PPU2's pin 100. We will be soldering 4Vpp level CSYNC out DIRECTLY from the CPLD's pin 15 (by way of the top pad of R9 which is connected via trace) on the mod board to the via from the top side (do not use CSYNC_o on the mod board.)
Spoiler
Image

Next, attach wires for CSYNC_i and MCLK_o. MCLK_o will be attached to the PPU2's pin 31 (XIN) which is also directly connected to PPU1's pin 100, the CPU, and cart slot pin 1. CSYNC_i goes directly to the lifted pin 100 on PPU2.
Spoiler
Image

Finally, affix the board and finish connections. Remember to bridge JP2 on the mod board. Power and ground for the dejitter board will come from U11, the reset IC - it's got nice thicc traces going to vias which tie into VCC and ground floods on the back.
Spoiler
Image
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Arthrimus
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Re: NES/SNES 240p dejitter mod

Post by Arthrimus »

maxtherabbit wrote:Wanted to document my install on SHVC-CPU-01. I elected to put the dejitter board on top, to reduce wire lengths.

The primary thing that distinguishes this install will be injecting the dejittered sync back into circuit before the video encoder in the SNES, providing dejittered outputs on CVBS, Y/C and RGBS.
Awesome work. This will be an great installation option for anyone brave enough to start lifting PPU pins. I've got a SNES mini and a 1Chip 01 (the very same one pictured in sofakng's post above incidentally) that I'm going to attempt this on also. I'll report my findings as well.
LDigital wrote: Is this an image of an installer 03? If I copy yours will it work like this? Been looking for instructions on how to install on mine
It's a 1CHIP 01, but the installation should be pretty much the same. The only real difference is that the CSYNC components you see pictured at the top of the picture are unpopulated on the 1CHIP 03 so you don't have to remove R12 since it's not there in the first place.
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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LDigital
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Re: NES/SNES 240p dejitter mod

Post by LDigital »

Arthrimus wrote:
maxtherabbit wrote:Wanted to document my install on SHVC-CPU-01. I elected to put the dejitter board on top, to reduce wire lengths.

The primary thing that distinguishes this install will be injecting the dejittered sync back into circuit before the video encoder in the SNES, providing dejittered outputs on CVBS, Y/C and RGBS.
Awesome work. This will be an great installation option for anyone brave enough to start lifting PPU pins. I've got a SNES mini and a 1Chip 01 (the very same one pictured in sofakng's post above incidentally) that I'm going to attempt this on also. I'll report my findings as well.
LDigital wrote: Is this an image of an installer 03? If I copy yours will it work like this? Been looking for instructions on how to install on mine
It's a 1CHIP 01, but the installation should be pretty much the same. The only real difference is that the CSYNC components you see pictured at the top of the picture are unpopulated on the 1CHIP 03 so you don't have to remove R12 since it's not there in the first place.
Many Thanks, My cable is luma sync. Do you know which I would need to disconnect and jump?
sofakng
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Re: NES/SNES 240p dejitter mod

Post by sofakng »

Would the SNES dejitter board cause the picture to be shifted at all?

The OSSC displays the picture perfectly, but my PVM seems to have the picture shifted to the left and I can't remember if it was like that before.

I can try the disable method (MCLK_EXT_i to CPLD pin 34) but hopefully I can get an answer before I have to solder. Also, does CPLD pin 34 have any pads or would I need to solder directly to the chip? (pin 34 is the first pin to the left of the "U1" label?)

EDIT: I've disabled the dejitter board and the picture is still shifted. It's not being caused by the board.

Would a sync stripper (Sync Strike) cause a picture shift?
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maxtherabbit
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Re: NES/SNES 240p dejitter mod

Post by maxtherabbit »

maxtherabbit wrote:Wanted to document my install on SHVC-CPU-01. I elected to put the dejitter board on top, to reduce wire lengths.

The primary thing that distinguishes this install will be injecting the dejittered sync back into circuit before the video encoder in the SNES, providing dejittered outputs on CVBS, Y/C and RGBS.

First, remove C5 and R6 as per marqs' instructions for SHVC-CPU-01. This severs the original xtal circuit from the CPU, PPUs and cart slot.
Spoiler
Image

Next, lift pin 100 of the PPU2, this will be our csync source to feed to CSYNC_i on the mod board.
Spoiler
Image

Next, scrape the solder resist off of the via immediately to the right of C69 :wink: this via is attached to the pad for PPU2's pin 100. We will be soldering 4Vpp level CSYNC out DIRECTLY from the CPLD's pin 15 (by way of the top pad of R9 which is connected via trace) on the mod board to the via from the top side (do not use CSYNC_o on the mod board.)
Spoiler
Image

Next, attach wires for CSYNC_i and MCLK_o. MCLK_o will be attached to the PPU2's pin 31 (XIN) which is also directly connected to PPU1's pin 100, the CPU, and cart slot pin 1. CSYNC_i goes directly to the lifted pin 100 on PPU2.
Spoiler
Image

Finally, affix the board and finish connections. Remember to bridge JP2 on the mod board. Power and ground for the dejitter board will come from U11, the reset IC - it's got nice thicc traces going to vias which tie into VCC and ground floods on the back.
Spoiler
Image
Upon further examination, I've discovered this console has jailbars. I don't remember seeing them before I did the mod, but then again I also didn't really scrutinize it prior to now. So my question: does anyone think that my placement of the dejitter board:
Spoiler
Image
could be producing jailbars? I thought since the PPU1 is digital in/digital out that putting the xtal on top of it would not cause any issues. The analog output pins of PPU2 are on the far left, furthest from the crystal. Not to mention the ground floods of the dejitter board itself acting as a shield.

I don't want to believe that the dejitter board is causing the jailbars, nor do I really want to go to all the trouble to undo the mod just to test the theory. What do you guys think?
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marqs
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Re: NES/SNES 240p dejitter mod

Post by marqs »

sofakng wrote:Would a sync stripper (Sync Strike) cause a picture shift?
I recall it uses a LM1881 so output sync is slightly delayed, causing picture to get shifted left a bit.
maxtherabbit wrote:Upon further examination, I've discovered this console has jailbars. I don't remember seeing them before I did the mod, but then again I also didn't really scrutinize it prior to now. So my question: does anyone think that my placement of the dejitter board:
SHVC-CPU-01 is known for faint jailbar-like artefact so I doubt it's related to the mod. You could try adding extra ~10uF ceramic SMD cap near PPU2's 5V supply pins since apparently that has helped some people.
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maxtherabbit
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Re: NES/SNES 240p dejitter mod

Post by maxtherabbit »

marqs wrote:
sofakng wrote:Would a sync stripper (Sync Strike) cause a picture shift?
I recall it uses a LM1881 so output sync is slightly delayed, causing picture to get shifted left a bit.
maxtherabbit wrote:Upon further examination, I've discovered this console has jailbars. I don't remember seeing them before I did the mod, but then again I also didn't really scrutinize it prior to now. So my question: does anyone think that my placement of the dejitter board:
SHVC-CPU-01 is known for faint jailbar-like artefact so I doubt it's related to the mod. You could try adding extra ~10uF ceramic SMD cap near PPU2's 5V supply pins since apparently that has helped some people.
will do, thank you
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