Search found 22 matches

by Ultron
Sat Feb 29, 2020 6:41 am
Forum: NES Hardware and Flash Equipment
Topic: Famicom AV Mod Situation in 2019
Replies: 133
Views: 106924

Re: Famicom AV Mod Situation in 2019

Wow, didn't realize there were so many new replies on this thread.

Just so everyone knows, the transistor you use is not that important, as long as it is an PNP transistor. It is being used as a voltage buffer. A jellybean 2n3906 or equivalent works just as well as the 2SA937 that Nintendo uses.
by Ultron
Tue May 14, 2019 1:49 pm
Forum: NES Hardware and Flash Equipment
Topic: Famicom AV Mod Situation in 2019
Replies: 133
Views: 106924

Re: Famicom AV Mod Situation in 2019

Wow, I think you are really onto something with that. This high frequency stuff can be sneaky though, depending how you were probing it, you may have formed a loop large enough to pick up radiated stuff. But it really does prove a point. When I wrapped one of my PPUs in copper foil, I soldered all ...
by Ultron
Mon May 13, 2019 9:00 pm
Forum: NES Hardware and Flash Equipment
Topic: Famicom AV Mod Situation in 2019
Replies: 133
Views: 106924

Re: Famicom AV Mod Situation in 2019

Just to show you the noise on the GND pin of the PPU on the NES-101 (using the heat sink as a reference): PPU GND Noise.png Meanwhile, the CPU GND pin is clean as a whistle: CPU GND Noise.png You can see the ~676 kHz noise on the GND pin, which is every 8th pixel, the same noise seen on the video.
by Ultron
Mon May 13, 2019 8:55 pm
Forum: NES Hardware and Flash Equipment
Topic: Famicom AV Mod Situation in 2019
Replies: 133
Views: 106924

Re: Famicom AV Mod Situation in 2019

I agree that it sounds like a layout thing. What could it be about the layout that causes the problem? From my experience in noisy environments, I have found that there is always a possible kludge once the problem is understood. Sometimes the kludge comes first before we understand it! That's kind ...
by Ultron
Mon May 13, 2019 2:07 pm
Forum: NES Hardware and Flash Equipment
Topic: Famicom AV Mod Situation in 2019
Replies: 133
Views: 106924

Re: Famicom AV Mod Situation in 2019

On the top loader NES-101, I was able to clean up the +5V signal by replacing almost all electrolytic caps with polymer electrolytic capacitors (I replaced the ones that mattered in this situation - Power). I replaced the main filter cap and the cap near the cartridge slot. I also added a 47uF in pl...
by Ultron
Sat Apr 20, 2019 5:31 am
Forum: NES Hardware and Flash Equipment
Topic: Famicom AV Mod Situation in 2019
Replies: 133
Views: 106924

Re: Famicom AV Mod Situation in 2019

So why does modded NES-101 have jailbars and AV famicom perfect (as usual)? Does the AV famicom have a different PPU revision? Because the NES-101 has the worst PCB layout known to man. A first grader could have done a better job of laying out the traces. My NES-101 has a -G, the AV Fami is -H. Tho...
by Ultron
Fri Apr 19, 2019 11:54 am
Forum: NES Hardware and Flash Equipment
Topic: Famicom AV Mod Situation in 2019
Replies: 133
Views: 106924

Re: Famicom AV Mod Situation in 2019

Now, the NES-101, with the same setup as the AV Fami (First shot screen is blurry, but you can see the jailbars): NES-101 Screen.png And the active video part: NES-101 Noise.png NES-101 Noise 2.png So, you can see, the jailbars have an approx. 667kHz period, or approx. 8 pixels. The jailbar itself i...
by Ultron
Fri Apr 19, 2019 11:42 am
Forum: NES Hardware and Flash Equipment
Topic: Famicom AV Mod Situation in 2019
Replies: 133
Views: 106924

Re: Famicom AV Mod Situation in 2019

I had some time today to do some testing. I modded my top loader NES-101 to use the same circuit as the AV Famicom. Here is the stock video circuit for the NES-101: NES-101 Video.png I replaced R1 with a 310 ohm resistor, and removed R2 and R3. In R2's spot, I connected a 220uF cap and FC2 in series...
by Ultron
Sat Apr 13, 2019 8:40 pm
Forum: NES Hardware and Flash Equipment
Topic: RGB Mod streaming question
Replies: 20
Views: 13119

Re: RGB Mod streaming question

MaarioS, This is good to hear. Is there an online resource or wiring diagram you know of demonstrating this? I think its clear i wont be able to do it but with some info my father can. It's simple. The "V" pad on the NESRGB board is the composite video out (already buffered and with correct termina...
by Ultron
Sat Apr 13, 2019 6:47 pm
Forum: NES Hardware and Flash Equipment
Topic: Famicom AV Mod Situation in 2019
Replies: 133
Views: 106924

Re: Famicom AV Mod Situation in 2019

Wow that's a nice o-scope. Thanks for taking the measurements, now at least we know that the bead is not a solution. Are the last 2 shots you took with the top left corner with your tantalum bypass cap or without? I do have to say, the composite out of the AV Famicom is WAY better than the NES or an...
by Ultron
Fri Apr 12, 2019 5:39 am
Forum: NES Hardware and Flash Equipment
Topic: Famicom AV Mod Situation in 2019
Replies: 133
Views: 106924

Re: Famicom AV Mod Situation in 2019

I took apart my AV famicom and verified that the ferrite bead looks exactly the same as the one I removed from the NES, and also that my AV famicom matches exactly your schematic Ultron. I dug into both of my NES's and found that they are quite different than the AV famicom, and actually each of th...
by Ultron
Wed Apr 10, 2019 6:57 pm
Forum: NES Hardware and Flash Equipment
Topic: Famicom AV Mod Situation in 2019
Replies: 133
Views: 106924

Re: Famicom AV Mod Situation in 2019

Do we expect the reactance to change as a function of frequency? I thought ferrites were comparatively ideal in that regard...? Yes, reactance changes with frequency in ferrite beads. I don't expect the bead to be the solution, but it would be nice to know its characteristics. If Ben Boldt has the ...
by Ultron
Wed Apr 10, 2019 5:58 pm
Forum: NES Hardware and Flash Equipment
Topic: Famicom AV Mod Situation in 2019
Replies: 133
Views: 106924

Re: Famicom AV Mod Situation in 2019

I actually did add an Amo-bead on the lead of the resistor connected to 5V. It had no visible effect when added in addition to the tantalum from 5V to GND. From what I understand, this is similar but different than a ferrite bead. They are definitely built different inside. We have these laying aro...
by Ultron
Tue Apr 09, 2019 9:50 pm
Forum: NES Hardware and Flash Equipment
Topic: Famicom AV Mod Situation in 2019
Replies: 133
Views: 106924

Re: Famicom AV Mod Situation in 2019

For whatever it's worth, the ferrite bead on my NES is 3.5mm diameter, 5mm long. Looking through through-hole ferrite beads available on DigiKey, I see they're all 10mΩ DC and in the range of 45-150Ω at 100MHz. (And when I measure its DC resistance, it's less than what my meters can measure). I'd r...
by Ultron
Tue Apr 09, 2019 8:01 pm
Forum: NES Hardware and Flash Equipment
Topic: Famicom AV Mod Situation in 2019
Replies: 133
Views: 106924

Re: Famicom AV Mod Situation in 2019

I was looking at the MAX4390 op-amp, it seems to be intended for this purpose. Though, I never imagined that a single SOT-23 part could cost several dollars! Wow. Do you have any emitter-follower ideas or an example I could try to build? Should I try to copy the circuit from the RF modulator you li...