Famicom av mod instructions?

[jpx72]

Xious> thanks, I remember you (or somebody here) already pointed that A13 thing here, but I haven't put much attention to it... How's the situation with the A13 on US NES by the way?

Da Bear> I have tested a couple of things on my setup, but the result wasn't very different. By connecting 47uF or 100uF between #20and#22, the lines were barelly visible, which is ok, but it was exactly the same result as when I had connected the 1000uF on #20 and #40. I even made a couple of photos, but there's not much to see (I have my video capture setup currently disassembled).

[Xious]

I don't recall if there was anything different on the NES (front-loading type). I think there is less interference from this line, but I didn't meddle too much with the NES layout. I figured that anything I design that would rectify this problem on a Famicom would be a universal solution.

One of my mates, who's an expect int he field of analgoue video was going to examine it with me, but he's been busy working 80+-hour weeks for the last several months, so we haven't yet sat down to closely inspect this problem. I do have some other areas that I will be examining this winter as well.   

[mamejay]

I had the same problem with the annoying buzzing and I found a fix for mine.

Just open up the player 2 controller and solder a wire just like in my pic.


Once I did this the buzzing went away and the controller and the mic work fine.

Hey Pikkon,

Just did an AV mod and had the buzzing audio.  Did you wire mod and it perfect now!!
Thanks for that!

Just on the AV mod.  I have done a few and the results are pretty good.  I just got a famiclone and the colours and brightness are so much better.  Is there a way to boast the video signal by modifying the amp in someway?

[Da Bear]

Just on the AV mod.  I have done a few and the results are pretty good.  I just got a famiclone and the colours and brightness are so much better.  Is there a way to boast the video signal by modifying the amp in someway?

Boost the signal on a Famicom or Famiclone?
On the Famicom I recommend you to reuse the Q1 transistor found next to the PPU for best colors och sharpness. It would probably work just as good in a Famiclone but I have never tried it.

[mamejay]

Just on the AV mod.  I have done a few and the results are pretty good.  I just got a famiclone and the colours and brightness are so much better.  Is there a way to boast the video signal by modifying the amp in someway?

Boost the signal on a Famicom or Famiclone?
On the Famicom I recommend you to reuse the Q1 transistor found next to the PPU for best colors och sharpness. It would probably work just as good in a Famiclone but I have never tried it.

Sorry I meant the Famicom.  The famiclone has AV out standard and looks so much better that the AV modded Famicom.  On the next one I will try using the Q1 transistor.

Anyone thought of using a PNP transistor like when building an AMP for the Sega Master system and Megadrive S-video outputs.
Would just be video in on the base and then a 75ohm resistor on the emitter to video out

[Da Bear]

Don't thinks it's so easy on the Famicom since it only outputs composite. The Megadrive/Genesis have a much more sofisticated video chip that outputs both RGB and composite. And as far as I understand, you don't tap the composite signal when doing an s-video mod on the Sega. Instead you use the Chrominance/Luminance output.

[jpx72]

I have found another modding attemp - this one requires desoldering the PPU and placing it on a separate board:
http://www2s.biglobe.ne.jp/~tns/hvc2/

NICE!

[2A03]

The Megadrive/Genesis have a much more sofisticated video chip that outputs both RGB and composite.

Technically the Genesis/MD VDP outputs RGB, which then goes to a video encoder chip that outputs analog RGB in addition to composite and S-video.

[Zombar]

Hi. I do av mod, but i'm have a problem. Look upside picture. Help me fix it.

[Xious]

Please provide photos of your actual modification, as well as a list of the parts that you used, if you want any actual (and helpful) answers...

Did you do this on a Famicom, or on a Dendy? 

[Zombar]

Dendy
No. Dendy have AV. Dendy is shit.
PCB HVC-CPU-GPM-02
http://www.h3.dion.ne.jp/~kuboken/famicom/famav2.html

[jpx72]

Well one thing is that you should try to put the components around pin #21 of PPU and not on the place where you have it.
Second, put a 47uF capacitor between pins #22 and #20 or 1000uF between #20-#40
Third, use shielded cables.
Fourth, try another mod, with PNP transistor.
Fifth: READ the whole topic, you won't have to ask questions like that anymore!  

[Zombar]

What kind of transistors have best picture quality?

[Xious]

I presume your worried about the distortion in the image, such as I see in the status bar there?

The NPN modification works just fine; I prefer a different transistor over the 1815 personally, but this will be alright. The methodology is not that great, as directly soldering the components like this always leads to potential problems.

I note that you did not use an electrolytic capacitor (condenser), which is against protocol. I suggest a 1µF electrolytic cap in place of your .47µF ceramic capacitor, with the negative axial connected to 'Video In' and the positive axial to your collector, and the 22kΩ resistor that bridges it to the +5VCD source .

You also need to tie your emitter to your video out connection via a 75Ω resistor; this will couple to the 220Ω resistor that is also connected between the emitter and GND/CE.


Finally, I advise removing this entirely and using a small piece of Vero board to assemble the components, then attach them to the correct points on the FC logic board with standard jumper wire, or shielded wire (at your discretion).

I also sell (assembled and parts-only) RetroVideo A/V kits, and (do-it-yourself) PCBs for A/V modification here.  

[Zombar]

Thnx for answer me.
What kind of PNP transistors have best picture quality?