Looking for troubleshooting advice on SNES dejitter install

[Xerxar]

Hey guys, hoping someone can give me some advice on things to check or change to get this working.

I already had an RGB bypass that i installed myself on my SNES Jr. I've also done an RGB mod myself on my front loader NES as well as the firmware update and dejitter mod on that machine and everything has been working great so i felt like i was competent enough to do this. After installing it i'm getting no signs of video from the SNES at all.

I tried some various things such as removing R14 on the board (i think i can put it back if needed, i still have it sitting in a safe spot on my mat), connecting JP3, with and without TTL on the RGB board. Each time i've done a test connection to my OSSC with no luck. I've verified i'm getting 10+ volts from the power supply. I've verified continuity with each wire and the backside of their connection points to verify good joints. csync output is going directly to the AV output. Some pictures: https://imgur.com/a/J3EmMsP

Again this was working fine prior to adding the dejitter board, i don't know if there is something special i'm supposed to do since i have a voultar RGB v.79 board or if i missed something entirely. Possibility of a bad dejitter board? Happy to test/check anything anyone can recommend or provide more pictures if needed.

[ldeveraux]

Hey guys, hoping someone can give me some advice on things to check or change to get this working.

I already had an RGB bypass that i installed myself on my SNES Jr. I've also done an RGB mod myself on my front loader NES as well as the firmware update and dejitter mod on that machine and everything has been working great so i felt like i was competent enough to do this. After installing it i'm getting no signs of video from the SNES at all.

I tried some various things such as removing R14 on the board (i think i can put it back if needed, i still have it sitting in a safe spot on my mat), connecting JP3, with and without TTL on the RGB board. Each time i've done a test connection to my OSSC with no luck. I've verified i'm getting 10+ volts from the power supply. I've verified continuity with each wire and the backside of their connection points to verify good joints. csync output is going directly to the AV output. Some pictures: https://imgur.com/a/J3EmMsP

Again this was working fine prior to adding the dejitter board, i don't know if there is something special i'm supposed to do since i have a voultar RGB v.79 board or if i missed something entirely. Possibility of a bad dejitter board? Happy to test/check anything anyone can recommend or provide more pictures if needed.

I just performed this dejitter mod on an NTSC SNES. I can crack it open this weekend and compare if you still need help by then.

[Xerxar]

I just performed this dejitter mod on an NTSC SNES. I can crack it open this weekend and compare if you still need help by then.

That may be helpful, I appreciate the response. So far i'm still in the dark, not having much luck finding troubleshooting techniques for the mods or SNES in general... the punishment for being an enthusiast right?

Thinking about trying to "undo" the mod and see if the system will work again which is the only way i can think of to tell if the dejitter board is bad/wrong.

[thebigcheese]

If I am correct in assuming that's a mini, then here is my install guide: https://retromods.game.blog/snes-sfc/sn ... d-install/. Includes many helpful pictures along the way, so hopefully that helps. It has been a while, though, and I am not very technically savvy, so I can't say I will be of much troubleshooting help.

[Xerxar]

If I am correct in assuming that's a mini, then here is my install guide: https://retromods.game.blog/snes-sfc/sn ... d-install/. Includes many helpful pictures along the way, so hopefully that helps. It has been a while, though, and I am not very technically savvy, so I can't say I will be of much troubleshooting help.

You are correct. I actually utilized your guide doing the install, it was very helpful. The only 2 differences i can see is that i have a different version of RGB board and my dejitter board is v1.3 instead of the 1.2 in your guide. I can't imagine these would be big enough differences to just have no video at all. Definitely leaning towards trying to put things back the way they were pre-mod this weekend unless someone has another suggestion by then.

[copy]

I also have a Voultar RGB bypass and dejitter combination in my 1CHIP-02, and I will be putting both in a Jr./Mini soon too.

Are you getting audio from your SNES?

On Voultar's RGB board, you may want to try removing the resistor between pin 3 of the multiout and the THS7374. This will ensure that only the dejitter board is driving csync. I think it should be this circled one, but you should double-check the continuity:

(EDIT: Picture removed. On further examination, I don't think your Voultar board revision has a resistor on the csync output. My apologies.)

Removing R14 on dejitter should not have changed anything. This resistor is not even in circuit when jumper J2 is open. This would only be needed for an NES installation anyway.

[Xerxar]

I also have a Voultar RGB bypass and dejitter combination in my 1CHIP-02, and I will be putting both in a Jr./Mini soon too.

Are you getting audio from your SNES?

On Voultar's RGB board, you may want to try removing the resistor between pin 3 of the multiout and the THS7374. This will ensure that only the dejitter board is driving csync. I think it should be this circled one, but you should double-check the continuity:

(EDIT: Picture removed. On further examination, I don't think your Voultar board revision has a resistor on the csync output. My apologies.)

Removing R14 on dejitter should not have changed anything. This resistor is not even in circuit when jumper J2 is open. This would only be needed for an NES installation anyway.

I appreciate any and all help at this point. I don't get audio with the OSSC because it is not syncing with the system. I did verify at the same time though that the system is at least functioning enough to allow me to connect with the SD2SNES through USB, so it's powering the cart, controller works and it's loading ROMS. https://imgur.com/a/JSkChoR

After this i thought to test it using regular cables to my receiver and i DO get audio, but still no video. So that's somewhat promising.

That makes sense about the csync resistor, from what i understand the way i have the wire run to AV pin 3 i should be bypassing the RGB board completely.

The R14 and J2 info is also appreciated, sounds like it would make no difference for me to put that resister back on.

[copy]

If it's outputting audio I gather the system is getting the new dejitter clock signal okay. All your connection points look correct.

Just an idea: try connecting dejitter CSYNC_o to the CS input pad on the RGB board. Leave the RGB TTL jumper closed like you have it now.

[ldeveraux]

Have you gotten this sorted, or should I still take some pics of my NTSC SNES with dejitter? I'll warn you, it also has the component mod, so YMMV.

[Xerxar]

Have you gotten this sorted, or should I still take some pics of my NTSC SNES with dejitter? I'll warn you, it also has the component mod, so YMMV.

I haven't yet. I'm trying to decide on trying to reflash the dejitter board, or remove it, i'm just not certain if i can get that C3 resister back on or not, it's like working with a fraction of a grain of rice haha.

My install i feel like looks like it should according to thebigcheese's guide so you don't have to take pics unless you feel like it. Maybe they would be handy to have to help anyone else doing a mod like yours.

[thchardcore]

Have you gotten this sorted, or should I still take some pics of my NTSC SNES with dejitter? I'll warn you, it also has the component mod, so YMMV.

I haven't yet. I'm trying to decide on trying to reflash the dejitter board, or remove it, i'm just not certain if i can get that C3 resister back on or not, it's like working with a fraction of a grain of rice haha.

My install i feel like looks like it should according to thebigcheese's guide so you don't have to take pics unless you feel like it. Maybe they would be handy to have to help anyone else doing a mod like yours.

If you have a soldering tip with a angle, wipe the traces clean with a few quick motions. Set the capacitor with a pair of tweezers and some flux. Tack one side and then remove tweezers and tack the other. SMD stuff is quite doable with a standard iron and a bit of practice.

[Xerxar]

Just wanted to give an update. I attempted to see if i could check/update the firmware but apparently my USB Blaster isn't compatible with this like it was for my NES and i got tired of trying to figure it out.

I proceeded to undo the mod and put the resistor back on C3, put the crystal back and put the csync cable back onto the RGB mod. Still get no video so I think this SNES is just dead at this point I can't think of anything i could have done to cause it but it is what it is. Thanks to everyone that tried to help.

[Jon Nielsen]

Stumbled on this thread while revisiting my SNES Jr to add digital audio out - and to tighten the job done with soldering and wiring.

For RGB video and sync mods my setup is almost identical. Only difference being that I use CS pad on Voultar's board and that S-Video is connected as well.

Anyhow. Studying OPs pictures I saw some of the same my install had. Potentially unsoldered strands on the connections.

Did you check bridges with a multimeter, especially in areas around the video wiring? And is it just me or is there a lose strand from a wire at R1?

Just a thought.