AV Mod for Original Famicom

[silkd]

I have an original (not clone) famicom. I was wondering if anyone has a good tutorial with parts needed on how to add av cables to the system. I got this system quite a while back and have never been able to get it to work with just the rf on my TV. I am not even sure if the system even works as I don't know if it is powering up. I have tried a regular rf switch that I have and have tried both channels 1 and 2 on the system and have scanned my television for the signal, but nothing. I would like to try adding av cables to it to test it out as I have nothing to lose at this point. If any one can give good detailed instructions and a parts list or just any help at all, please respond. Thanks.

[Shawn]

I have an original (not clone) famicom. I was wondering if anyone has a good tutorial with parts needed on how to add av cables to the system. I got this system quite a while back and have never been able to get it to work with just the rf on my TV. I am not even sure if the system even works as I don't know if it is powering up. I have tried a regular rf switch that I have and have tried both channels 1 and 2 on the system and have scanned my television for the signal, but nothing. I would like to try adding av cables to it to test it out as I have nothing to lose at this point. If any one can give good detailed instructions and a parts list or just any help at all, please respond. Thanks.

 

 

Try it on channel 43 or 83 on your TV (seriously).

[silkd]

I have an original (not clone) famicom. I was wondering if anyone has a good tutorial with parts needed on how to add av cables to the system. I got this system quite a while back and have never been able to get it to work with just the rf on my TV. I am not even sure if the system even works as I don't know if it is powering up. I have tried a regular rf switch that I have and have tried both channels 1 and 2 on the system and have scanned my television for the signal, but nothing. I would like to try adding av cables to it to test it out as I have nothing to lose at this point. If any one can give good detailed instructions and a parts list or just any help at all, please respond. Thanks.

 

 

Try it on channel 43 or 83 on your TV (seriously).

 

 

I have tried all channels with the switch on both 1 and 2. I know the power supply and rf work as they work fine on my Super Famicom on both 95 and 96 depending on the channel switch there. I am not even sure if the famicom system is powering from the lack of led. I would like to just try to mod it with av cables to give it a shot. If anyone has diagrams on this, that would be great. Is there any kinda way to hook up a led somewhere to test if the system is even powering on? Thanks.

[gdement]

Is there any kinda way to hook up a led somewhere to test if the system is even powering on? Thanks.

I don't know about hooking up an LED, but I guess what I'd try is use a multimeter to see if you can find any voltage. You could test on a capacitor or one of the Vcc pins, or maybe there's a convenient place to test coming from one of the ports. You could also do this on a game cartridge rather than the machine itself. Just find a spot that you feel confident you won't accidentally short anything.

[silkd]

About the only thing I am worried about is shocking the piss out of myself as I really do not know too much about electronics. I can follow directions like a mofo though The only thing I see about VCC listed is a chip with 4 pins labeled (V, A, IN, VCC.OUT) would I just use a multimeter on the VCC.OUT and ground the other end? Please excuse my ignorance

[gdement]

The first thing I should say is I'm not very experienced with electronics either, so I might not be the best person to get advice from.

 

Yeah, to check the voltage, you just need to put the negative probe on some grounded piece of metal, something safely outside the famicom would be fine. Put the positive probe on the point you want to check, taking care not to arc anything. Make sure you're in VDC mode.

 

Vcc is the label they use for the supply voltage input on the IC chips. If you test the Vcc pin on any of the chips, you should get a reading of about 5V when compared with ground.

 

The pins are numbered starting from an indentation or circular marking, and moving counter-clockwise.

On a DIP chip (the rectangular type with pins that go through the board), Vcc is *usually* the last pin. However, you can't really be sure without checking the datasheet for the chip. Nothing bad will happen if you test the wrong pin though. At least I'm 99% confident of that...

 

I looked up the datasheet for the 6502, and noticed that chip is one of the exceptions - they put Vcc somewhere in the middle of the first side.

RAM chips though are very likely to have the voltage on the last pin - that seems to be the convention with RAM.

[russdog]

You may already know this, but just to be sure, I'd like to make sure you know that the CPU in the NES does not have the same pinout as a 6502. Like mentioned, the 6502 has the +5V pin in a strange location (a lot of old CPUs were like that, such as the 6800 and I think the Z80 too), but the NES's CPU has it in the normal location (pin 40, top left pin). As far as adding AV to the old Famicom, two of the wires on the ribbon cable connecting the modulator/power supply to the mainboard carry audio and video. I don't remember which one (I can find out for you if you need me to), but my suggestion is find one that leads ONLY to the cartridge slot (this is the audio), and one that leads ONLY to a transistor (this should be the video - see if the transistor's base is connected to pin 21 of the RP2C02E-0 or RP2C02G-0 chip). Just to let you know, the video will be weak - you will either need to make your own video amp, or you can modify the mainboard to put out a full-strength signal (this will saturate the RF signal, but you probably won't be using this anyway, right?). Please let me know if you'd like for me to post instructions on how to boost the video signal strength without adding anymore transistors or chips. Oh, and I wouldn't be too worried about getting shocked by the Famicom - just keep your hands dry, don't press on anything really hard, and if you really want to be safe, unplug it and leave it turned ON. By the way, if you remove the modulator, you can add your own circuit board with audio/video jacks. If you run the incoming DC supply through a bridge rectifier, then to a capacitor and a 7805 regulator, this will allow the Famicom to work on just about any 9-12 volt power supply, and polarity, or even AC (like the NES supply, which typically blows up unmodded Famicoms). One more thing, if you plan to make your own board to replace the modulator, you may want to consider an RGB conversion, if you don't mind doing a complex project.

[DeadlyDiskKun]

I used a "NES RF Switch" on my Famicom (1983); surprisingly most parts on the two systems are interchangeable.

 

 

 

Edit- I opened up my Famicom and looked at the RF port, its hardwired and not possible to remove it without damaging the system. So I do not recommend trying to convert RF into AV.

Edited May 30, 2007 by DeadlyDiskKun