NESRGB installation issue

[lolitsevan]

Hi, I recently purchased and NESRGB kit for my frontloader. I'm not as experienced with modding as most here (but I've done quite a bit of work on snes', so I know how to solder a little), so i figured I'd see if anyone here has any idea where to start troubleshooting my issue. I got everything wired up according to diagrams I've pieced together from this forum and others, as well as tim's guide on his website(ntsc, jumper 5 soldered), and I wired up a multiout for the rgb/svideo, but I'm experiencing wavy 'interference' (you can't see shit, so more interference than video) on composite (thru multi and onboard) and svideo(via multi). fwiw svideo seemed to actually react to what the game was supposed to be doing, but you still couldn't see anything. I seem to be experiencing the same interference when i plug an rca cable into either the onboard audio or video (red or yellow) onscreen.

a video of the issue I'm trying to describe >>>> https://youtu.be/72OVr0hk2K4

s-video test >>>> https://youtu.be/yHjl_sy54HE

if anyone has any insight into this specific issue, I'd really appreciate it! I can post pics, or more videos or whatever if anyone's willing to help point me in the right direction. I'd also like to know if this problem is generic/symptomatic of bad installation work too, whatever anyone can tell me. Thanks again!

[viletim]

What is the first video of exactly? The TV connected to the V output on the NESRGB board? Is there a particular reason why the first video has music, but the first one doesn't?

I don't know what's wrong exactly. If you have a multimeter handy, you can try these passive tests listed below.



This assumes you have a NESRGB with a PPU soldered onto it sitting in a socket on the NES motherboard? Disconnect the NES from the TV and power.

First test:
Set the multimeter to continuity mode. Test the continuity of the PPU signals between the PPU and the base of the NES motherboard. All pins connect straight through except 2-9 and 14-17. If a continuity is not present when it should be this indicates a bad solder joint. This is more common on the Famicom and top loading NES which requires an adapter board (and more solder joints).

Second test:
Remove the NESRGB from the motherboard (you can leave the PPU and wiring in place). Set the multimeter to resistance mode. Measure between 5V and ground. It should be greater that 1 k (kiloohm). If it is less can indicate a faulty video buffer amplifier on the NESRGB board. It shorts out the power rail when it fails.

Third test:
With the red (positive) probe on the ground and the black (negative) probe on the pin, measure in sequence the resistance between ground and each PPU pin 2-9, signals DP0-DP7. They should all measure similar to each other and is usually a value between 1 and 10 M (megaohms). One pin that measures significantly different to the others usually indicates a fault or bad connection on the NESRGB board. Measure again, but instead of measuring the resistance at PPU pins, measure at the pins protruding from the bottom of the NESRGB board. Signals DB0-DB7.

[lolitsevan]

sorry if I wasn't clear, the first video is trying to get signal from the composite and mono audio modules on the console, so whatever would output to those, maybe nothing? V is hooked up to composite on the multiout, so unless signal is still being passed thru the board to those connections I wouldn't expect to get anything. My assumption was that I got no audio/video on the first test because nothing is being fed to those connections anymore, but I wanted to test something besides the multiout I soldered.

The second video is an aftermarket snes svid cable(that I know works) thru the multiout, which presumably is getting all the signals its supposed to be getting from the nesrgb (all pins soldered except csync, but I don't have any csync cables so this seemed redundant, all my scart cables are luma sync).

Thanks for the response though! I'll try to find some time today to run the multimeter over what you suggested, it seems like you're thinking bad solder connections, which would make sense to me considering I'm getting stereo to the multiout, so presumably the board is working and being fed atleast power and audio.

Also, preliminary, but I just popped the nesrgb out of socket so I could check the solder on the ppu legs, and I can hardly see any on the bottom of the board connecting the row of legs nearest to the expansion bay(those were hard to solder to in socket, should've taken them out, haha). So, I'll do what I can with the multimeter and hopefully check back with positive results!

[lolitsevan]

Hey, so I had a minute to try a few more things and took a few more videos. I tested continuity between the points you suggested, and found some errors which I fixed, and now I'm getting what seems to be more video information, but its still garbled. Also, rgb has a good deal of interference not present on svideo, but that could just as easily be my connections to the multiout, unless someone has some other idea.

https://youtu.be/KwgPFutU2Gk <<<< svideo update

https://youtu.be/iuI94MhJRMc <<<< rgb test thru scart-yuv box (theres not supposed to be gamesound on this one, audio not connected to component audio on tv)

in my video i mentioned rgb having more interference, but then when i put svideo back on I was experiencing similar interference, and some jittering that wasn't there when I checked before. Also, it seems like the palette switch can have an effect on interference levels, atleast when I switch between different palettes the interference is different.

I'm still trying to figure out how to measure resistance with my ancient multimeter and not fry anything, so I'll try to check those issues soon.

edit: so I tested some more stuff, tried touching up the solder joints a bit, and then i got this >>>> https://youtu.be/6vSV8dJR9WQ
so, it worked for a bit, then I don't know if the opening looped or what happened, but it went back to what it was doing before. The fact that the video was correct (minus interference) for a while makes me hopeful, but still confused as to what might be causing this.

[CkRtech]

Hey lolitsevan,

Any more progress on this?

In addition to your PPU solder joints on the board, did you also check the various AV/Ground/power connections to the NESRGB board and at the S-video connector? Are your power and ground signals nice and solid?

Btw - Did you use the external voltage regulator? I don't even know if that is still supplied in the kit like it was a year ago.

The interference could be noise in your video signal from surrounding signals, iffy ground connections, or even a poor quality S-Video cable. I think you mentioned seeing that in composite output as well, so it is probably an internal problem.
The weird, not-so-quite-working graphics look *could* be from your 72 pin connector/dirty cartridge. I assume it was working well before your mod, though, and it is also rather unlikely.

...just thinking out loud.

Check your power and ground joints. Make sure those are good. What sort of gauge wire did you use for getting power/ground to your NESRGB (if you used the voltage regulator)?

[lolitsevan]

hey, sorry it took me so long to get back, i ended up having bigger issues when i was trying to move things around and ended up screwing up the socket, so I think I'm just going to send it off to someone more qualified, haha. One thing though, I noticed in one guide that it said to use a larger gauge wire for power and ground, which I did not. I used 28 awg for everything. I did use the external voltage regulator, and the 72 pin connector was replacement that I know works, same with the svideo cable, I use that for testing and I know if I do things right it should be without interference.