Famicom AV Modification / Mod

[80sFREAK]

2 P You have wrong level of video signal.
Post Merge: August 03, 2012, 04:22:32 pm
Another epic thread

[P]

So the problem is that they just soldered the AV cables directly to the boards without any components? I forgot to mention that this mod was already applied when I got the system. I haven't touched anything yet.

According to 133MHz newer TV sets might give up on video if the signal isn't good enough thus not showing a picture. That could explain why the picture randomly won't show up on my LCD. If I fix this mod that shouldn't be a problem anymore.


OK I read through this thread and that thread over here: http://www.famicomworld.com/forum/index.php?topic=4713.285 and come to the following conclusions:

(All cables should be shielded and as short as possible to reduce noise.)

1) Wrap the PPU in copper tape and ground the copper to pin 20 on the PPU.
But how do you put copper tape on the underside? Do you have to desolder the PPU?

2) Build an AV amplifier.
This is the most confusing one as there are almost as many variants of the amplifier as there are tech savvy people. But the one by jpx72: http://jpx72.detailne.sk/modd_files/fc/avmod.htm seems good and this one http://www002.upp.so-net.ne.jp/jsrc/densi/fcav2.html too. This last one seems a bit more complicated than most and he doesn't seem to try to keep the cables to the amplifier short.

3) To get sound without noise add a 220uF electrolytic capacitor (volt doesn't seem to matter on the capacitor) between audio output (pin 46 on cartridge connector) and the audio output jack if it's not done in the amplifier schematic already.

4) If there still are jailbars try the following:
*Add three extra ceramic capacitors, the bigger the better. One on pin 22 and the other two on the power lines around the PPU and the CPU.
The +5V is pin 40 for both the PPU and the CPU as far as I understand.
*Put a 47uF ceramic capacitor between pins #22 and #20 on the PPU or put a 1000uF (ceramic?) capacitor between #20-#40
*Lift the video pin (pin 21) on the PPU.


That's about it. The AV mod sticky thread could use a summarized list like this. But is it correct? Anything to add?

[80sFREAK]

That's why i don't like to release any information... People don't read, but ask questions...
READ STICKY THREAD. THERE IS EVERYTHING YOU NEED

[P]

Of course I read that sticky! And allot of other threads as well if I might add (or else I wouldn't understand much of it)! Maybe I wasn't clear enough but that sticky doesn't really summarize all this, does it? Also I'm sorry but I think the sticky doesn't really answer my questions. You don't have to if you don't want to but I'd be happy if someone with more knowledge than me could help and summarize the steps and we could eventually add it to the sticky thread. I don't think I'm the only one who is confused.

[80sFREAK]

Maybe I wasn't clear enough but that sticky doesn't really summarize all this, does it? Also I'm sorry but I think the sticky doesn't really answer my questions.

I wonder if next question will be "do i need to plug soldering iron into wall socket".....
1)it's obvious and described with photos in sticky thread
2)answered in the sticky thread
3)sound? noise? thats something new. maybe you talikng about mic in second pad?
4a)check
4b)READ STICKY THREAD AGAIN
4c)check

[P]

I've seen that you have put down lots of time and contributed allot to this information and I must say good job on the sticky thread. It's something that has been missing from this forum. I just want to help make it more clear and improve it, so scratch that ironic attitude please.

1)it's obvious and described with photos in sticky thread

Yeah the pictures show pictures of desoldered chips from your famicom keyboard project but I would rather not desolder the PPU if it's possible but I guess it's not.

2)answered in the sticky thread

Point number 2 is a statement not a question.

3)sound? noise? that's something new. maybe you talking about mic in second pad?

No it was something I read in these discussions somewhere and I thought it wasn't covered in some amplifier schematics so I added it. But I guess I mixed up things. Scratch point number 3.

4a)check
4b)READ STICKY THREAD AGAIN
4c)check

Point number 4b Isn't mentioned in the sticky. It's something I read somewhere else or mixed it up somehow. I guess it's obsolete now. Scratch point number 4b.

Again these points are not questions but a summarizing of everything I learned here. But I kind of mixed some question into it to learn more. Sorry if my post was more confusing than useful, and thanks.

[80sFREAK]

all good, all sorted.

[famifan]

1) Wrap the PPU in copper tape and ground the copper to pin 20 on the PPU.
But how do you put copper tape on the underside? Do you have to desolder the PPU?

if you copper tape/foil is strong enough you can use a neddle and thread to push it on the underside. Desoldering is not necessary. I used foil and it works for me. Also don't forget about insulating insertion between PCB and copper foil.
http://www.famicomworld.com/forum/index.php?action=dlattach;topic=4713.0;attach=2029 pic

[P]

Thanks famifan it was something like this I was looking for. However I looked at my PPU again and it looks quite tight under there. Well I'll just have to give it a try. About insulation, yeah I kinda figured it out looking at those pictures but that's something that I think should be explained more in the sticky thread. Many people might not know why you have that stuff in the picture without an explanation.

all good, all sorted.

Yes thanks. I'm glad we can discuss this without having any childish flame wars.

[famifan]

About insulation, yeah I kinda figured it out looking at those pictures but that's something that I think should be explained more in the sticky thread. Many people might not know why you have that stuff in the picture without an explanation.

insulation is needed to prevent a junction/short circuit between copper foil and PCB's surface. Use any insertion you can get. Thin cardboard or strong paper works as well.

[jpx72]

2 80sFREAK:

That's why i don't like to release any information... People don't read, but ask questions...
READ STICKY THREAD. THERE IS EVERYTHING YOU NEED

No there isn't. You haven't posted the mod itself, and it would be really helpful if you can choose the best amp per revision:
These are just some of the schematics available in this and other threads:







this last one is from my page and you suggest replacing the output cap with a smaller one:


And you have also sent me (in a PM) different instructions for  rev07, which even included removing one component from board.
SO which should I choose? Is there a need for removing components from board?

[80sFREAK]

1)Stop confusing people with irrelevant schematics there is absolutely no sence about value of components.
2)Do you understand word "rebuild"?
3)Do you understand phrase "i am after first one"?
4)I do remove components from PCB to reuse them - i do not fuck around $1 orders even with free shipping
5)Once you lifted pin 21 video amplifier components on PCB are useless

If you want some more explanations, it will be more about theory and more complaints "oh, it's to complicated, i wanna something more simple....." This is basics, which ANYONE MUST KNOW if want to do something with electronics.

[jpx72]

Okay so:
1) that's why I have posted these here and not in that other topic you've created
2) yes, but if you mean rebuild the "exact same" video circuit as is the original (on board) you could have wrote that. Otherwise, I don't understand.
3) no, and I don't understand the whole part there"I'm after first diagram with 100R and 150R insted of 220R and 2k2" ..if you want us to rebuild the original, why do you change the resistor's value?
And also the next part: "In the video circuit you don't need to use 220uF separating capacitor. 22uF or 33uF is far enough." - now you're reffering to the schematics on my website? because there is no 220uF capacitor in your picture... Can you understand now why I am confused?
4) ah okay, now I understand. I don't order components, I am passing a nice store on my way home from work every day where I can buy almost everything for prices like 0,05€ per resistor/capacitor.
5) I know, but you haven't said a thing about lifting the pin 21 in your topic!!

Thanks for your answers, please don't take this as an assault on your person, I just don't understand and asking doesn't hurt...

[famiav]

Help! I unsoldering the PPU and I installed it on a support (such as photos of 80'Freak) and now I have a gray screen, or when an image full of pixels, but I sound that is corrupt.

My Famicom is dead?

[jpx72]

2&3) Ok so now I am completely lost, but don't bother explaining, cause I don't think it will be productive...
5) No trolling, this forum is pretty much without troll, as you may have noticed, and I'm trying to keep it that way.
Post Merge: August 10, 2012, 04:55:29 am

... but Sharp Twin as well.

Sorry missed that one.