Topic: I have always had these questions (and disappointment) about my nes !!!

I own a NES console since 1994 ( I am 25 now) and I cannot understand 3 things till today:

1) Why on earth when I use rf cable jack mode, I can see video but hear NO AUDIO SOUND at all? That was the way I played this console those early days , because our televisions then didn't support SCART or compositional audio/video input holes , so the only way was to connect it directly to the antena hole via rf cable jack. Nowadays that I have a TV with SCART or audio - video holes , I can connect via audio-video cable mode (red and yellow) and the game loads in the AV channel of TV , with working audio.

2) Why some games were NEVER supported in my nes? I remember my cousin bought me a game (Donkey Kong) but it never loaded (probably , bought from USA or Greece ( I live in Greece) I am not sure , I don't remember, she later bought and gifted me a Game Boy Donkey Kong game to compensate, hehe ) , same thing happened several years later with a cartridge from France i think (that's explain "FAI" word in the bottom-right in the back side of a cartridge?) But I think I found the solution myself , because my nes is actually bought from UK (my grandma bought it when she was on a journey in London and gifted to me when she returned to Athens) , so is it true that can play ONLY cartridges from UK? ( "EAI" in the back of the cartridge like this: http://prntscr.com/83cpfr )
Also , this is my bottom of my NES , http://prntscr.com/83ct7q , pointing out its UK origin.
And speaking about the bottom of nes , here's number 3...

3) What is the slot at the bottom of nes about? A mystery to be solved too. http://prntscr.com/83crjo

Thank you in advance, and I hope my mysteries/questions be solved soon

1) I could be the tuning of the TV. If you still have the TV using RF check for fine tuning under the channel settings. You might just have to tweak it a little for the audio to come through,

But using the AV ports gives better video output and you can set it up to have a dual speaker audio (Not stero but at least sound comes out both speakers on a TV)

2) Region Locks
USA NES which was NTSC won't work on a PAL NES.
Also there were two versions of a PAL NES. PAL-A games (Mattel or Nes-version) were sold in the UK and Italy, and PAL-B games in the rest of Europe (Scandinavia, Germany, France, Spain etc). It's not possible to play PAL-A games in a PAL-B console and vice versa.

3) This is a cover for an expansion port under the system. This would have been used for a NES disk drive or other add-ons which never came out.

1) Sorry , I didn't understand what you mean here , I just used an rf cable , from rf cable jack hole to antenna hole of TV and searched the channel where the video outputs via the remote tv control. When I find the channel , the video is fine but I hear no audio , that's all , and I cannot figure a way to fix this problem, hauting me for over 20 years

And speaking about video quality , even with AV cable (red-yellow-white , with white not used) the picture is kinda bad , comparing to running a nes emulator on PC , which the video quality there is fantastic , but it lacks the smoothness (fps maybe) of playing in the real thing !!!! Any idea to improve video quality? I just ordered an AV2HDMI adapter , it may work if i connect my nes to a hdmi screen , who knows ?

For example here you are , the difference I mean:

i) Picture from TV monitor with my NES (picture is from mobile phone , ignore the blue lines created by the photo , notice at graphics I have highlighted with red rectangles , they are not straight and good looking) http://prntscr.com/83f9rd

ii) Picture from a NES emulator in my PC (notice how clear it is, there are no curly lines at graphics, they are straight, clear lines) http://prntscr.com/83f5rs

2) Well , that's make a sense , I already bought "Duck Hunt & SMB" from eBay from a UK user-store , because I knew that only cartridges from UK gonna work! But , since you mentioned Italy , can I try buying italian cartridges (they are cheaper , because of euros , instead of uk pounds, GBP) ? Will they work with my NES?

3) Hmmm , I googled it a bit too , yes , it think it's obsolete and no need at all.

Anyway, thanks for quick answer but I really wanna fix the first problem soon!!!!

OK, So you have tried various TV? Then it would say that the problem is a fault with the RF unit in the NES. This would need to be swapped out with a new unit and would require soldering.

The reason the emulator looks bettter than the NES is down to because it is getting a clean image from straight from the emulator. This bypasses the old SD AV hardware which is being output which has a max resolution of 256x240. The emulator not only gets the clean image but it also upscales the image.

The AV2HDMI will imrpove the output of the NES on a HD TV but there is still a limit to what it can do as you are still using the old hardware at the start.

For connecting to a HD TV to play NES I've found that the Retron 5 works well, as the games are emulated they look as well as a PC emulator running on the same HD TV. Also it's regionfree and can play loads of consoles with the original controllers.

2) Yes, if it's a PAL "A" region cart it should work. (from what I've read, A should be UK and Italy (as well as Australia, but you're probably not likely to import from there as shipping would be much higher, from what I've seen) and B is all other European countries. Hong Kong was a third PAL region, though it wasn't supported for very long, it sounds like.)

You can disable the lockout chip of your NES. It's very easy, just Google it. Then you can play both PAL A and PAL B games without a problem. Most USA games will also boot but will run slower and may have glitches.

Perhaps there is some difference between the RF signal in the UK and Greece.

Also you can get an adapter that will let you play Famicom games.

To mod the NES you need to break one of the legs on the NES10 (Lockout) chip. It's a simple open system up and cut a piece of metal.

Well , I don't want to risk it at the moment because I am afraid that I will do more harm than good or ruin my NES forever! Anyway , I still can find some cartridges from UK eBay if I want.

Now , for the cable thing (my first and most important mystery to solve) , I have the following black RCA cable (which, weird, I found out that it can work as audio or video cable too , like the yellow-red-white ones.

http://prntscr.com/84cyyc

And I am connecting it like this:

http://prntscr.com/84cxy9

Unfortunately I don't own the original nes rf cable for this , but still as far as I remember , it was a cable like that and always got video signal , like now, in a random tv channel , but no audio. And I thought, does this cable is capable to carry only video at a time? Do I need to buy a special RF NES cable which is able to carry both video and audio? I believe it is possible , who knows...but you will say that since I own a AV triple color cable and connect it with the audio/video method, the video there is better and I have audio too , but still I want to solve the mystery that haunts me for 21 years...the missing audio via rf cable connection.

Could the problem be that there are several PAL variants (according to Wikipedia, there's at least four PAL formats that were used in Europe, not counting SECAM)?
I don't know for sure, just putting out suggestions.
(the only similar stores I have heard for NTSC were people buying RF Famicoms from Japan and using them in America, which were sometimes accessible with video and sound on different channels on US TVs. It sounds like different people had different results. It sounds like the problem with that is that, while NTSC video format was effectively compatible, the RF was designed to output at a different frequency. Yes, like in the US, the NES was designed to output on the frequency of either channel 3 or 4, as I believe it was regulated that, when analog TV was operational, only one of those two were allowed to be used by an actual TV station in a city, so users were told to switch their console to the one that wasn't used locally to avoid interference.
Could it be something similar in your case? Your console designed around UK analog TV broadcasting, and your Greek TV broadcasting was different?)

Hello , today I received 2 adapters , one AV2HDMI and HDMI2DP.

I tested connecting nes yellow video cable to the AV2HDMI adapter first (which is powered by USB) and then via a male/male HDMI cable , I tried an HDMI samsung monitor, but the video quality didn't change at all and the worst thing is that tearing appeared , I mean that video lag.

Same things happened when I tried also an AOC 144Hz screen with DP input only (the reason I used the 2nd HDMI2DP adapter, which is also powered via a 5V socket adapter) , so I connected as this : yellow nes video cable ---> AV2HDMI --> HDMI2DP --> DP male/male to monitor.

Graphics remained same , like nes (not pixel fixing , as I mentioned in a previous post) , and also tearing appeared again...

Duck hunt (nes zapper) does not work on the hdmi screen too , didn't try to the DP AOC 144Hz screen yet.

Why graphics quality didn't change on the above monitors (hdmi and dp) and why video tearing appeared? I have to mention that playing nes in a classic CRT TV screen , had no tearing at all , I mean the games run super smooth!

You mean the Zapper doesn't work? Light guns are known to not work on HD TVs. The display technology in HDTVs is not compatible with them.
They only work on CRT TVs.