Composite and audio on a PAL NES "toaster" - how to guide

[bacteria]

I have spent many hours working this out.

The box of tricks you get on a PAL NES "toaster" console is a circuit board about 2" x 2" enclosed in a heavily secured shilding unit that takes some work to remove and separate from the main board, then open up and get to the board.

This box has the AC in (yes, AC in not DC), RF output, composite and mono audio output. The AC goes into components then into a 7805 (hence no need for the AC as it converts to DC for the 7805), and the 7805 although outputs negative, isn't present on the small board. Confusing!

Anyway, after various tests and trimming, etc, worked out what is needed for the video. The video line from the motherboard is too weak so needs amplification, which is why it moves to the transistor. The audio also passes through various circuits, although needs no amplification as you can take it straight off the NES motherboard fine.

I looked on the net for options, found a few but they were for the NTSC NES 2 unit, and frankly, doesn't work on this PAL NES unit, I tried it.

Not knowing a great deal about electronics (learning though slowly), no idea what the coil is or how to rate it, what I do know is the circuit does not work without it present.

The pic below is the board after removing all the shielding, the RF modulator parts, etc. The parts circled are the parts you need for this mod. Keep the 7805 too. A 7805 is easy to wire - the pin nearest the "7" is the 7.5v in, middle is negative, and the "5" pin is the 5v output.



Schematic I made



Pic to clarify - now I know what works, I can wire it up properly!

[hardrrocker]

Do you ever sell your modded works? Just wondering

[Satoshi_Matrix]

wait...the PAL toaster NES doesn't have composite output? Is it RF only like the NTSC NES 2?

[bacteria]

The PAL NES "toaster" has outputs for RF, composite and audio (mono), and input for AV to power the system.

On the daughter board, AV is converted into DC which goes into a 7805 which steps the voltage down to 5v which goes into the motherboard. I haven't looked at the traces on the motherboard yet to see where the 7.5v DC goes into as it does go onto the motherboard, I was just expecting to see 5v going there.

The audio and composite signals come from the motherboard into the daughterboard, the audio doesn't need amplification even though it seems to get some (works without fine), although the composite line is weak so needs the amplification on the daughterboard, which also puts both the audio and composite together of course to make the RF. We don't need the RF however so a lot of the daughter board isn't needed.

What was confusing was the positive voltage from the 7805 was converted into negative rather than being tapped off the 7805's negative, probably something to do with the AV not DC input. It did mean however I couldn't just follow traces on the board as usual, was far harder than that. The only guides I could see on the net were for the NES 2 American system, which clearly was different for PAL units as the schematic didn't work, the way i've posted above is very easy indeed to perform, although took me many hours to work out what was needed and what not.

As with the SNES, using DC instead of AC, means more parts are not needed too, system powers itself on automatically.

[Satoshi_Matrix]

Sorry, I'm pretty technically minded (I do all sorts of mods myself) but I still don't understand. What does this mod do? What is the purpose? What is gained over a stock NES? Amplified....video???

[bacteria]

Ok, in most circumstances, people want to mod an old console to do composite where it only does RF, attach to RCA connectors, close the case up and volla, you can now play on your modern television.

What i'm into doing, Saroshi_Matrix, is making the boards smaller in order to make them into handheld portables (using original console hardware) or as with this NES unit, making it smaller and compact so it takes the least amount of space in the mega multi-integrated console unit (the Alpha Omega system i'm building). This also includes removal of groundings, etc as can get away with.

The purpose therefore of the mod posted here is a small part of making the board as small as possible, by removal of the daughter board and working out the parts required to use DC not AC and composite and audio. The components mentioned in the pics amplify the video signal from the motherboard into composite compatable PAL output. Removal of the RF abilities is also beneficial as it removes the need for shielding for all included systems as there is no RF interference.

So, I guess this, and the other mods i'm doing to the PAL NES "toaster" console are of interest to a portablizer rather than a general modder, as there is no extra benefit to a general modder if the board is 1/3 its original height overall, about 80-90% it's original size and reduced and rewired as required - however, is of interest to someone making handheld portables. There seemed no information on the net as to what was needed to amplify the composite signal on a PAL unit, hence this posting.

[Satoshi_Matrix]

Hmm...even still, the NES motherboard is very large. Were you planning on cutting it and rebuilding portions?

[bacteria]

I am in the process at the moment of cutting it down. Might be possible to get it down to 95mm x 160mm assuming I can safely remove a bank of flat capacitors ok. That's pretty small.

[Satoshi_Matrix]

Why not try to portablize the Famicom, AV Famicom or NES 2? They all have PCBs so much smaller.

[bacteria]

Very easy question to answer. I live in the UK, the only NES console I have ever seen here is the NES "toaster", the original one; never seen any other model - that may have been the only one in the UK. I know the Americans had choices of NES systems, not us by the look of it. I got three NES "toaster" units, so modding them - making them region free is a doddle, and apparantly will work on 95% of NTSC games, about 75% without any graphical issues or garble (obviously NTSC games running at PAL speed - not a problem).

Making the board small, probably removing about 20% of the original board size and also about 2/3 of the thickness (mostly thanks to removal of the useless expansion port).