Famicom av mod instructions?

[MaxWar]

Dang, I tried the AV mod on my CPU-07 famicom and I still get nasty jailbars.

 I followed the steps on the page http://jpx72.detailne.sk/modd_files/fc/avmod.htm

I even did the extra step of unsoldering the PPU, putting it in Socket and covering the underside with grounded metallic tape ( I could not find the copper one so i used aluminum tape)

I followed the steps exactly. I made the circuit very compact, I used Tantalum caps because i could not find Ceramic caps of the proper value. I respected the polarity and used shielded video cable.

Am i the only one?

[Rosser]

Dang, I tried the AV mod on my CPU-07 famicom and I still get nasty jailbars.

 I followed the steps on the page http://jpx72.detailne.sk/modd_files/fc/avmod.htm

I even did the extra step of unsoldering the PPU, putting it in Socket and covering the underside with grounded metallic tape ( I could not find the copper one so i used aluminum tape)

I followed the steps exactly. I made the circuit very compact, I used Tantalum caps because i could not find Ceramic caps of the proper value. I respected the polarity and used shielded video cable.

Am i the only one?

You should really go with copper its a much much better ground you can get a thin copper sheet if you can't the adhesive copper tape

have you tried replacing the transistor and the resistors its super cheap and can't hurt to try

also this may sound stupid but have you tried to adjust the brightness on your tv I notice a lot of people have their tv adjusted too high on brightness scale which may be appropriate for modern gaming not some much for old school stuff 

[MaxWar]

Thanks for reply.
Well, I looked at a few convenience stores and they did not have the copper tape. I guess i could look at one of the big surface place.

I used the Transistor from the board. Did not try to replace it. Tut said it was the best choice.

As for replacing the resistors, honestly i dont see how it could change anything.They are just standard 1/4/w resistors, they work or not, right?

Seems to me that this problem is interference related. Maybe i put some part too close to some trace or something?

Also, for the 0.1 uf cap, they did not have ceramic caps at my electronic store so they sold me a Tantalum one. Unlike the 33 uf one, it does not appear to have any polarity.
Could this cap be a problem??

My brightness is not too high. Its about in the middle. It does not look that much bright actually so i dont think thats the issue.

The jailbars are visible enough to be distracting.

[MaxWar]

Did you grounded shield? Did you built your video amplifier around pin20? Did you disconnected pin21 from PCB? Did you added some capacitors on the power rails? If one of your answers "no" - you didn't followed "how to". Read it again and do it again. Once you follow exactly the steps, you will get a good result.

I grounded both cable shield and Metallic tape on PPU.

Well, i followed exactly the steps in the link i gave ( The orange page ) and it does not tell me to do all those things. ( except for vague allusions in step 8 )

But i see now that on the same page there is a link to a thread by you that provides different instructions along with more details.
The instructions on the orange page says it is the best method so this is what i followed.
But it does not even make you disconnect pin 21 from board, It makes you use the existing trace to connect pin 21 to the base of transistor.

Ill do more tests tomorrow, going to sleep now.
Post Merge: December 02, 2012, 05:40:42 pm
Alright, I redid the mod a bit differently, and i swear, im not having any luck, it does not seem any better. ( OR very very slightly )
Jailbars are there and not very subtle.

I did not lift the pin 21 but i cut the Trace on the underside  of the PCB, it no longer connects to anything but the mod.
Im not 100% sure what you mean by building the amp around Pin 20 ( Ground ) So i used pin 20 for all my ground connections.
I have two 0.1 uf ceramic caps ( i found some ) connecting 5v  to ground   Between pin 22 and 20 of PPU and between Vcc of cpu and ground.  

Here are some pics.
Open in separate window to zoom.

What should i try at this point?  Make the circuit on the top of PCB and completely lift leg 21?

[MaxWar]

I added another one between pin 40 of ppu and ground. How many of them do i need to add?
I have 3 so far and it does not seem to improve very much.

Post Merge: December 04, 2012, 04:00:26 pm
Well, I tried a different circuit, the one on consol5



And it works better for me. Almost completely eliminated jailbars.
They do not show at all in most games but you can still faintly make them out on pale colored uniform backgrounds like in the intro of crysis force, Or the splash screen of the goonies.

Adding caps on the power lines seemed to help a bit but switching to this circuit made the biggest difference on my machine. I don't know why.
Maybe ill try adding further more caps and see if i can get to completely 100% remove the bars even on pale uniform backgrounds.

[Alboma]

Hello! I am very new to the forum so bear with me. I got a famicom from ebay. I have tried using the NES RF cable, TV channel 95/96, VCR, etc etc but cannot get the famicom to work. It has been modded previously as the ch1/2 switch was removed. I suspect the famicom has been modded to PAL RF, so my only solution is the AV mod. Too bad I threw away the multi-system TV many years ago.

The sound works. I use pin 46 from the cart connector. I got no luck on video out. Actually now I am not even sure if PPU pin 21 works. I had built the video circuit using a prototype board, but now I want to isolate it and test PPU pin 21 instead. How should I connect this pin to the TV? All I got now are many RCA video connectors. Should I use one and hardwire it to pin 21? By doing this I must desolder the transistor Q1 from the board correct? Many thanks! I want to make sure pin 21 gives out video before troubleshooting on the video circuit that I built.

[jpx72]

People searching for the best AV mod, please don't post another schemes for god's sake, read this topic:
http://www.famicomworld.com/forum/index.php?topic=8080.0
you cannot find a better solution, it's simply not possible!

[Frank_fjs]

Clearer instructions would be nice though.

[jpx72]

For the basic mod you can use my webpage with step by step inatructions based on 80sFREAK's findings. If you want to make yourself a crystal clear image, you need a lot more experience and you won't be asking for "clearer" instructions.

[Alboma]

Hello again! Sorry for no photo last time as I was not ready to take photos. I've desoldered Q1 2SA937 and tested the PCB after. I connect PPU pin 21 directly to TV, bypassing the video mod circuit part. Still nothing is shown. As mentioned before the famicom has been modified before, with channel 1/2 switch removed. Sound output from cart pin 46 is working. Start and reset button are working, as I test it with a game. I decide to use a prototype board for the mod circuits. I've attached some photos. Please see and advise what cause the no video output even directly from PPU pin 21. I don't want to declare the PCB had been faulty, at least not yet. Thanks!

[keropi]

that's a clone machine , right? 
the shell looks original though 

[Alboma]

famicom

EPIC FAIL!

Based on the chips and the PCB? If yes then thanks for the productive response. Then I can stop wasting time on it. I can always look for another famicom on eBay, but yes it's getting rare. Only this time I will find a AV mod directly.
Post Merge: January 04, 2013, 11:39:54 am

that's a clone machine , right?  
the shell looks original though  

Actually I got the machine from a eBay seller. It came with original packaging and instruction manual. As said before the machine had already been modified by someone. You can see from the picture that I needed to tear off the sticker on a screw in order to open the case. From the photos pls see if it's cloned or not.

But never mind that. It looks like I will not get any positive response here. In fact I'm not coming back here. Peace out.

[Frank_fjs]

What a cheeky eBay seller!

[jamisonia]

So I just performed the new AV mod on my Famicom after having done the mod that was listed on http://jpx72.detailne.sk/modd_files/fc/avmod.htm around a year ago.  I saw it had been updated, and I always had faint jailbars.  I decided to do the new mod, and to my surprise the jailbars got much much worse.  They are dark black vertical bars.  Additionally I now have diagonal bars.

I haven't added the foil, but currently I have lifted pin 21, and followed the guide otherwise.  I seemed to have the most luck last time with a 1000 uF cap between two points on the PPU, but I forget what those two points are.  Any other suggestions for reducing the jailbars?  I certainly didn't expect them to get worse.   

I read some illusion to adding more caps along the power rails, and this thread would provide more specifics, but I haven't seen the specifics. 
Post Merge: January 22, 2013, 08:00:19 am
so I added 12 0.1uf Caps between as many exposed 5V lines as I could fine.  This reduced it quite a bit.  I'll try the copper tape later.  I've noticed some games look worse than others.  My FDS games look nearly as clean as a toaster NES. 

[vlade-1]

Warm greetings from Soviet Russia to everyone!

This is about GPM-02 famicom revision, for others there might be some differences.
Anyways you always should double check all actions.

I want to tell another success story of famicom console av modding.
I used the instruction from http://jpx72.detailne.sk/modd_files/fc/avmod.htm as a start.

At first I made it exactly as it was said(except step 6 and 7), and I had a jailbars problem.
Also, at that time I did not understand the step 7 at all. Well, this may be because I am not good at English, also in technical terminology.
The next step was to place capacitor between 22 and 40 legs of PPU. This would make the jailbars more thin but they was still there.

Then I followed instruction from http://www.famicomworld.com/forum/index.php?topic=8080.0

I wanted to make a shield, but did not got the instruments to solder PPU correctly, so I found that PPU has some distance from the board, where the shield can be placed. Then I got some copper foil(had to detach some from the textolite board) glued it to the paper sheet and pushed under the PPU.
For easy shield insertion I had to remove capacitor C44 from board, then I soldered it back in place from the other side of the board.
After that I have detached the 21 pin of the PPU from the board. Then I moved the scheme from the bottom of the board to the upper part and attached it as on the photo.
Also I moved the 0,1uF capacitor to the position which 80sFREAK suggests. I think it does not change anything just the GND contact is closer.
After this operations I notice some jailbars improvements. They were more sharp before, now they became more soft.

The last step was to put some additional capacitors on the other side of the board. The main graphic improvement have made the red colored capacitor, the others make it slightly better. I suppose the two or three would be enough for my system, but I put 7 of them on every chip power line except the PPU.

This makes the image quality 99% perfect.

I have attached photos of my work. I suggest Guests should register and sign up to see them.

My thanks to 80sFREAK and jpx72.