Famicom av mod instructions?

[thepandaofnom]

I am planing to av mod my famicom( once I get it in) and I am getting all my materials together. I got a big box of parts donated to me and I found some metal poly caps that are rated at 1.0uf /100 vcd and its part number is digi-key ECQ-E1105KF. I was planing to use them to use in step 4 of  http://jpx72.detailne.sk/modd_files/fc/avmod.htm . So my question is are they comparable at all or should I just go and buy some actual ceramic caps.

[fredJ]

I follwed the "new mod" guide on this page: http://jpx72.detailne.sk/modd_files/fc/avmod.htm

I must say, the image quality is top notch, in my opinion. Maybe some slight, slight jailbars, but hardly noticable. I'm happy about the video quality.

My question is regarding the sound, which wasn't succesful at all. There is a buzzing / humming sound, and clearly it reacts to the image. ("black" screen has another frequency of humming than "blue" screen, so to speak). I used shielded cable, and grounded the shielding for both audio and video. I added a 220uF electrolytic capacitor as the guide suggested. I have tried different connections. I have tried routing the audio to my tv, my headset and my music centre. They all get the humming sound.

I live in Europe, and therefore I use a stepdown converter to power the beast.

Here you can see (and hear!) an examble: https://www.youtube.com/watch?v=NUR0-VWNgEs

Any suggestions on how to fix the sound?

Basically, that's how it is on a famicom. I have been working a bit on trying to find a solution for this problem too. It seems more common on the newer model famicom revisions (with FF logo on the front). But basically, the sound inside the famicom go all around and disturbances are picked up from the PPU or CPU.
There could be some trick similar to the pin 21 lift that fixes jailbars. I don't think that adding a bunch of caps everywhere will improve the sound. (we have done some testing) It also isn't because of the power supply.

But I seriously don't think the sound is a major problem the way it is in your video, it doesn't affects the experience of playing. Playing a 30 year old machine isn't like playing a HDMI machine on a HD TV.

[TwentyOne]

Hello!
Maybe someone can help me with advice.
I got Famicom with AV mod, but it have jailbars problem and I want to solve it.


Here is the photo of famicom:

Motherboard revision is HVC-CPU-GPM-02.

In the lower right corner - this is just LED, not part of AV mod.

[hvc01]

seems the board was modded using the method in this guide
http://jpx72.detailne.sk/modd_files/fc/avmod.htm

i would isolate pin 21 (see step #2) by cutting the leg on the other side of the board as close to the board as you can and solder yellow wire directly onto the isolated leg.

perhaps the trace wasn't cut completely and that is why the jailbars are so prominent.

[maikerusan]

Hi, I'm very new to modding. I'm currently giving the Famicom AV mod my best shot, following the guide on this site, http://jpx72.detailne.sk/modd_files/fc/avmod.htm
I have some questions I hope someone can help me with.

Progress thus far:
In desoldering the Q1 transistor, I broke the middle leg off, so I had to reorder a new one. In the meantime, I believe I've built the rest of the circuit so that I just need to solder in that transistor once it arrives. I also desoldered the Ch 1/2 switch to make space for the video out rca jack.

I'm also waiting on some 1uF ceramic capacitors, so I haven't added those between pins 20 and 22 of the PPU or pins 40 and GND of the CPU.

I also haven't run the audio cable with the 220uF resistor from pin 46 yet as I have a question about that.
I was originally following this guide http://www.assemblergames.com/forums/showthread.php?49263-GUIDE-AV-mod-your-Famicom in which he routes the video to the original RF jack and then the audio to the new RCA jack. (I changed guides after realizing that I had a newer revision of the Famicom, the HVC-CPU-GPM-02)

In the new guide that I'm following, it says "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." In my picture, I have the blue wire running from the negative of the 33uF capacitor, but...am I supposed to be installing TWO new RCA jacks, one for video AND one for audio (as opposed to somehow using the old RF jack for video?)

If I do need a 2nd RCA jack, is it ok to simply desolder the old RF jack, cut it off with a diamond cutter, and use that space?

Also, once I have soldered the wires to the RCA jack cinches, do I need to run ground wires from each of them to some point on the board? Isn't the video wire already grounded in the circuit with the Q1 transistor, 100R and 150R resistors, etc to pin 20 of the PPU?

Thanks in advance for your help!

[jpx72]

Of course you can use the RF cinch for video or audio, just cut the trace that goes to the middle pin and solder your wire there. Ground is already there, no need to run it from other place.

BTW I see you don't use shielded wires (a wire composed of a 1.metal wire, then a 2.plastic cover, 3.metal shielding and 4.another plastic cover). All the interferences that are produced on the PCB can easily affect your wire and create jailbars or other interferences, no matter how awesome you make your mod. Don't underestimate this, use shielded cables instead.

[maikerusan]

Thanks for your quick reply.
When you say to cut cut the trace to the middle pin and solder my wire there, I'm assuming you mean on the bottom side of the PCB? It looks like all the of pins are soldered in one big glob. (Picture attached) Would I need to suck that solder off and then cut a trace? Could I also desolder that pin and lift it up (like with pin 21 of the PPU) and solder the audio or video cable to that?

As for the wire, thank you for your advice about shielded cables. Would you mind linking me to exactly the type you would recommend? I live in Japan and its actually much more difficult than you'd expect to find specific types of cables. Speaking Japanese doesn't always help because they often use generic terms like "speaker cable" to refer to a large range of different wiring. If I had a link with a nice image, I can at least search around online until I find a matching image. That's mostly what I've been doing to learn all these new terms like "capacitor", "resistor", "transistor" etc, In Japanese, haha.

[maikerusan]

following the guide on this site, http://jpx72.detailne.sk/modd_files/fc/avmod.htm

I don't think so.

#1 Any low power silicon PNP transistor will do the job.
#2 Do not avoid shields
#3 Keep wires as short as possible
#4 Take ground from pin20 PPU. Don't ask why, just do it.
#5 An AV cable from secondhand shop will do the job. Hint - use PS1 cables, they are long and have good shelding. Last time i bought them for about 100yen each. If you need thin multicore wires, get LPT cable - they are obsolete now, so in junk bins of secondhand shop you can find one for 100yen.
#6 RCA sockets are nice, but... wire cables directly.

#1 I didn't have any other transistors lying around, so I had to order some. I was able to find the 2SA937 ones really cheap, so I got some of those.
#2 I wasn't avoiding shielding on purpose. I didn't know I was using incorrect wiring until jpx72 said so.
#3 The wires are definitely shorter than mine in jpx72s site, but he didn't include the 150R resistor in his circuit. I thought my location of the 33uF capacitor was best in order to keep the 150R wire short. (I assume it's not ok to have it siting on top of the PPU?) And as I mentioned, I'm very new to all of this, so I'm not skilled at all with getting super short connections soldered beautifully.
#4 The black cable is/was to be my ground wire to the transistor. And unless I'm mistaken, it currently is soldered to pin20.
#5 I can get AV cables easily for sure. I'll try to get the ps1 cables if possible. Thanks for that advice!! I only need the shielded cable for the video and audio wires, right? Or should I use them for the ground to pin 20 as well?
#6 I'll wire one of the cables to the original RFs pin on the bottom of the PCB like you've recommended, but I have no choice but to solder the other one to the cinch of the new RCA jack, correct?

[oare]

Hello!
Maybe someone can help me with advice.
I got Famicom with AV mod, but it have jailbars problem and I want to solve it.
(...)
Motherboard revision is HVC-CPU-GPM-02.

Here's another quick and easy solution, after http://vaot.mydns.jp/fc/noise5.htm.

The basic idea is to increase the capacitance of the decoupling capacitors wherever seems relevant, so you can either change the capacitors for higher valued ones, or add other capacitors in parallel.
I opted for the latter, adding a total of 9 x 2.2uf SMD capacitors to the spots circled in red.



Here are a couple of close-ups. You'll see there are still a few jailbars afterwards, but they're a lot less noticeable. These pics are taken from very close, on a monitor that is very sensitive to jailbars.
They're also basically completely gone in every plain color but brown (which is why I used this color for the sample pics).

Before:


After:

[xIceMan]

I recently did the mod again but I didn't have a 220uF capacitor to solder between pin 46 and audio jack so I used a 820uF one and I have to say that it works even better with the sounds / noise reduction.

[TrenTech]

Purchased pre-modded Famicom(BAD IDEA) and the picture quality is terrible. Classic jail bars and some sort of interference like watching antenna tv with bad reception.  Any suggestions for improvement would be greatly appreciated. board revision is hvc-cpu-07

http://imgur.com/IoX0XAE,YdCIzwp#0
http://imgur.com/IoX0XAE,YdCIzwp#1

[Pikkon]

I bet pin 21 of the ppu is not even lifted,does RF work on it?

[TrenTech]

I Wouldn't know. Don't have what I need to test. I've already went a head and lifted pin 21 as well as removed the transistor from the board which did clear up the jailbars however the interference still remains.

[Pikkon]

I would take the yellow wire that's connected to video and solder that to the lifted pin and see if that gets rid of the interference.

[TrenTech]

I already did that after I lifted the pin.

I also thought that it could be the added circuit, I haven't found any schematics that match it, so I built the one from the link below onto a breadboard, and swapped the circuits temporarily . This produced the exact same results. at that point the only difference between my setup and the one in the link is step 4, which I couldn't do because I have no clue where the needed connections are for this particular revision mainboard. at this point I'm out of ideas.

http://jpx72.detailne.sk/modd_files/fc/avmod.htm