Famicom AV mod - NEW!

UPDATE: I have prepared a better AV mod instructions, for removing the jailbars from video output. Not much changed really, I only added isolation of pin #21 to the old one. JPx72@26.1.2014:

Before you start making this mod, read this topic!
http://www.famicomworld.com/forum/index.php?topic=8080.0

For questions and answers please reffer to this topic on FamicomWorld forum:
http://www.famicomworld.com/forum/index.php?topic=4713

For experienced users, here is the needed schematic:

Covered all revisions: HVC-CPU-01 to 08, and HVC-CPU-GPM-02.
THE SCHEMATIC IS THE BEST SOLUTION OUT THERE SO FAR (aug.2012) !!!
ONE VERY IMPORTANT THING: ISOLATE THE PIN 21 FROM THE MAIN BOARD!!!


For everyone else, here is my NEW solution:

NEWS: THIS SOLUTION WORKS BEST ON MODEL HVC-CPU-GPM-02 , OTHER REVISIONS STILL HAVE JAILBARS AFTER THIS, BUT IT'S THE BEST YOU CAN DO! If you want old solution - go HERE

I recommend this solution, since it is a nice solution for everybody! It is based entirely on schematics and jailbar-free solution of 80sFREAK!
My solution requires removing one component from Famicom main board and IT WILL DISABLE your RF (antennae) output!
If you don't want to remove anything from your Famicom board /or you want to preserve the RF output,
then don't do this!
I recommend removing the Q1 transistor because you will get better video output this way.
You can use any other transistor, but your video output will NOT be so clear.


Step 1:

Remove transistor 2SA937 (marked Q1 on board)

Step 2:

ISOLATE PIN #21 OF THE PPU!
This can be tricky, but VITAL for removing the "jailbars" from the video output.
Check this picture I borrowed from this website (thank you!):

This guy is showing us where the noise is originating.
Since the trace from pin 21 is running too near to the noised trace (from pin 25),
it can be affected by it. So we need to get rid of the trace
going from pin 21 to transistor Q1.
THIS can be done in two ways, for best results I recommend the first one:
1) desolder the pin 21 and lift it upwards, so you remove the connection of pin 21 with the main famicom board.
2) cut the trace going from pin 21 to Q1. BUT you have to cut it on two places like on this picture from DaBear (thank you!)

Step 3:

I recommend building this on the components side (where the chips are) of the main famicom board
because the shorter the connecting wires, the less jailbars you will get.

Bend pin marked "B" ("base" of the transistor) like shown on the picture
and put it near the PPU with the pins facing up.
Solder pin "B" to pin 21 of the PPU (video).
Next, solder pin "C" ("collector") to pin 20 of the PPU (GND).
Next, solder 150R resistor to pin 22 of the PPU (+5V).

DO NOT remove pins 20 or 22 from the main board, just solder directly to them. The only pin that needs to be lifted is PIN 21!

Next, solder 100R resistor to pin "E" ("emmitor"), and connect other ends of both resistors (100R and 150R) together.
Next, solder a 33uF resistor's + pin (I used electrolytic, 80sFreak recommends ceramic) to the two resistors.
The negative pin of the 33uF capacitor is your composite video output! So solder a wire here, that will go to the middle tip of your video cinch.
For video output use shielded cable, and connect the cable's shield directly to pin "C" of the transistor or pin 20 of the PPU.

You can check some photos of my work here,
but observe only the transistor placement,
on the photos I took the +5V from another place and not pin 22.
Also on the photos you can see I removed the whole PPU and placed it in a socket. This is not recommended.

(If you accidentaly break one of the "legs"/pins of your transistor Q1 don't worry, you can use any other PNP transistor!)

If you are lost in this step, just follow this schematic:

It is vital to keep all wires as short as possible.

Step 4:

Solder a ceramic capacitor 1uF between pins 20 and 22 of PPU.

Also solder a ceramic capacitor 1uF between pin 40 of the CPU and the near GND

like you can see on THIS picture.

For even more reducing the bright vertical bars ("jailbars") on screen

STOP- at this point you should have very decent video output, if not, consider next steps -STOP

Step 5:

This step is OPTIONAL (although highly recommended by 80sFREAK for reducing the jailbars)
and NOT recommended for unskilled people:
Desolder PPU and shield the bottom of the PPU by a piece of copper coil (foil).
Solder the copper coil to pin 20 of PPU (GND).


(photo by 80sFREAK)


SOUND

Step 8:

You can take sound from the "SOU" marked solder-spot on the Rev.01-08, or simply from pin 46 of the cartridge connector (all rev.). You should add a 220uF electrolytic capacitor like this:

Pin 46 of cartridge connector:

 




I have also prepared for you some pictures of different Famicom board revisions.
I don't have all the pictures, so will be happy if you can add more to my library:

HVC-CPU-01
HVC-CPU-02
HVC-CPU-03
HVC-CPU-04
HVC-CPU-05
HVC-CPU-06
HVC-CPU-07
HVC-CPU-08
HVC-CPU-GPM-02a
HVC-CPU-GPM-02b
HVC-CPU-GPM-02c
HVC-CPU-GPM-02d
HVC-CPU-GPM-02e
HVC-CPU-GPM-02f
HVC-CPU-GPM-02g
HVC-CPU-GPM-02h
HVC-CPU-GPM-02i
HVC-CPU-GPM-02j
HVC-CPU-GPM-02k....?